89. Atlas, WI; Ban, NC; Moore, JW; Tuohy, AM; Greening, S; Reid, AJ; Morven, N; White, E; Housty, WG; Housty, JA; Service, CN; Greba, L; Harrison, S; Sharpe, C; Butts, KIR; Shepert, WM; Sweeney-Bergen, E; Macintyre, D; Sloat, MR; Connors, K. (2021) Indigenous Systems of Management for Culturally and Ecologically Resilient Pacific Salmon (Oncorhynchus spp.) Fisheries.Bioscience 71: 186-204 Indigenous Systems of Management for Culturally and Ecologically Resilient Pacific Salmon (Oncorhynchus spp.) Fisheries
traditional knowledge; salmon; sustainable fisheries; mixed-stock fisheries; Indigenous governance
Pacific salmon (Oncorhynchus spp.) are at the center of social-ecological systems that have supported Indigenous peoples around the North Pacific Rim since time immemorial. Through generations of interdependence with salmon, Indigenous Peoples developed sophisticated systems of management involving cultural and spiritual beliefs, and stewardship practices. Colonization radically altered these social-ecological systems, disrupting Indigenous management, consolidating authority within colonial governments, and moving most harvest into mixed-stock fisheries. We review Indigenous management of salmon, including selective fishing technologies, harvest practices, and governance grounded in multigenerational place-based knowledge. These systems and practices showcase pathways for sustained productivity and resilience in contemporary salmon fisheries. Contrasting Indigenous systems with contemporary management, we document vulnerabilities of colonial governance and harvest management that have contributed to declining salmon fisheries in many locations. We suggest that revitalizing traditional systems of salmon management can improve prospects for sustainable fisheries and healthy fishing communities and identify opportunities for their resurgence. DOI PubMed
88. Atlas, WI; Seitz, KM; Jorgenson, JWN; Millard-Martin, B; Housty, WG; Ramos-Espinoza, D; Burnett, NJ; Reid, M; Moore, JW. (2021) Thermal sensitivity and flow-mediated migratory delays drive climate risk for coastal sockeye salmon.Facets 6: 71-89 Thermal sensitivity and flow-mediated migratory delays drive climate risk for coastal sockeye salmon
climate change; conservation; fisheries management; migratory species; Bayesian mark-recapture
Climate change is subjecting aquatic species to increasing temperatures and shifting hydrologic conditions. Understanding how these changes affect individual survival can help guide conservation and management actions. Anadromous Pacific salmon (Oncorhynchus spp.) in some large river systems are acutely impacted by the river temperatures and flows encountered during their spawning migrations. However, comparatively little is known about drivers of en route mortality for salmon in smaller coastal watersheds, and climate impacts may differ across watersheds and locally adapted salmon populations. To understand the effects of climate on the survival of coastal sockeye salmon (Oncorhynchus nerka; hIsn in Hailzaqv), we tagged 1785 individual fish with passive integrated transponders across four migration seasons in the Koeye River-a low-elevation watershed in coastal British Columbia-and tracked them during their relatively short migration (similar to 13 km) from river entry to spawning grounds. Overall, 64.7% of sockeye survived to enter the spawning grounds, and survival decreased rapidly when water temperatures exceeded 15 degrees C. The best-fitting model included an interaction between river flow and temperature, such that temperature effects were worse when flows were low, and river entry ceased at the lowest flows. Results revealed temperature-mediated mortality and migration delays from low water that may synergistically reduce survival among sockeye salmon returning to coastal watersheds. DOI
87.Moore, JW; Connors, BM; Hodgson, EE. (2021) Conservation risks and portfolio effects in mixed-stock fisheries.Fish. Fish. 22: 1024-1040 Conservation risks and portfolio effects in mixed-stock fisheries
diversity‐ stability; ecological portfolio effects; mixed‐ stock fishery; Pacific salmon; resilience; sustainable fisheries
Fish biodiversity sustains the resilience and productivity of fisheries, yet this biodiversity can be threatened by overharvest and depletion in mixed-stock fisheries. Thus, the biodiversity that provides benefits may also make sustainable resource extraction more difficult, a key challenge in fisheries management. We simulated a mixed-stock fishery to explore relationships between different dimensions of biodiversity and fishery performance relative to conservation and fishery objectives. Different dimensions of biodiversity (number of stocks, evenness, asynchrony among stocks, heterogeneity in stock productivity) exacerbated trade-offs between fishery and conservation objectives. For example, fisheries targeting stock-complexes with greater asynchrony, and to a lesser extent richness, had greater stability in harvest through time but also greater risks of overfishing weak stocks and reduced yield compared to less biodiverse stock-complexes. These trade-offs were ameliorated by increasing management control-the capacity of fishery managers to harvest specific stocks. To explore these trade-offs in real-world fisheries, we contrasted the fishing and population status of individual stocks within three major mixed-stock sockeye salmon (Oncorhynchus nerka, Salmonidae) fisheries-Bristol Bay, Fraser River, and Skeena River. In general, the fisheries with lower management control had individual stocks that were more often being over- or under-fished, compared with those with higher management control, though variation among regions in biodiversity, scale of management, and magnitude of habitat alteration likely also contribute to these relationships. Collectively, our findings emphasize that there is a need to extract less or regulate better in order to conserve and benefit from biodiversity in fisheries and other natural resource management systems. DOI
86. Pitman, KJ; Moore, JW. (2021) The role of large, glaciated tributaries in cooling an important Pacific salmon migration corridor: a study of the Babine River.Environ. Biol. Fishes 104: 1263-1277 The role of large, glaciated tributaries in cooling an important Pacific salmon migration corridor: a study of the Babine River
Pacific salmon; Oncorhynchus; Babine River; Water temperature; Climate change; Riverscape
Climate change and its associated symptoms, such as warming air temperatures, glacier retreat, reduced snowpack, and increased variability in precipitation, are warming rivers and lakes. Such warming water temperatures threaten cold-water fishes in some regions. For instance, warm water temperatures can kill or harm anadromous Pacific salmon as they migrate upstream to spawning grounds. In this study, we assessed how tributaries, and their relative watershed properties, shape temporal and spatial dynamics of temperatures during the summer months in a salmon migratory river. We focused on the mainstem of the Babine River of British Columbia, an important migratory corridor for steelhead and the five eastern Pacific salmon species, but particularly for sockeye salmon that spawn in stream reaches above the Babine Lake, at the river's headwaters. We discovered that large glacier- and snowpack-fed tributaries cooled the Babine River by approximately 2 degrees C over its 96 km length. Different tributaries played different temperature functions. Cooler and more glacierized rivers were associated with a bigger change in temperature between upstream and downstream sites. Understanding how water temperatures change during adult salmon migration, especially within riverscapes on the edge of potentially harmful temperatures, can help inform proactive management options in a warming world. DOI
85. Price, MHH; Moore, JW; Connors, BM; Wilson, KL; Reynolds, JD. (2021) Portfolio simplification arising from a century of change in salmon population diversity and artificial production.J. Appl. Ecol. 58: 1477-1486 Portfolio simplification arising from a century of change in salmon population diversity and artificial production
artificial production; biodiversity loss; conservation genetics; fisheries; historical ecology; population diversity; portfolio effects; salmon abundance
Population and life-history diversity can buffer species from environmental variability and contribute to long-term stability through differing responses to varying conditions akin to the stabilizing effect of asset diversity on financial portfolios. While it is well known that many salmon populations have declined in abundance over the last century, we understand less about how different dimensions of diversity may have shifted. Specifically, how has diminished wild abundance and increased artificial production (i.e. enhancement) changed portfolios of salmon populations, and how might such change influence fisheries and ecosystems? We apply modern genetic tools to century-old sockeye salmon Oncorhynchus nerka scales from Canada's Skeena River watershed to (a) reconstruct historical abundance and age-trait data for 1913-1947 to compare with recent information, (b) quantify changes in population and life-history diversity and the role of enhancement in population dynamics, and (c) quantify the risk to fisheries and local ecosystems resulting from observed changes in diversity and enhancement. The total number of wild sockeye returning to the Skeena River during the modern era is 69% lower than during the historical era; all wild populations have declined, several by more than 90%. However, enhancement of a single population has offset declines in wild populations such that aggregate abundances now are similar to historical levels. Population diversity has declined by 70%, and life-history diversity has shifted: populations are migrating from freshwater at an earlier age, and spending more time in the ocean. There also has been a contraction in abundance throughout the watershed, which likely has decreased the spatial extent of salmon provisions to Indigenous fisheries and local ecosystems. Despite the erosion of portfolio strength that this salmon complex hosted a century ago, total returns now are no more variable than they were historically perhaps in part due to the stabilizing effect of artificial production. Policy implications. Our study provides a rare example of the extent of erosion of within-species biodiversity over the last century of human influence. Rebuilding a diversity of abundant wild populations-that is, maintaining functioning portfolios-may help ensure that watershed complexes like the Skeena are robust to global change. DOI
84. Steel, JR; Atlas, WI; Ban, NC; Wilson, K; Wilson, J; Housty, WG; Moore, JW. (2021) Understanding barriers, access, and management of marine mixed-stock fisheries in an era of reconciliation: Indigenous-led salmon monitoring in British Columbia.Facets 6: 592-613 Understanding barriers, access, and management of marine mixed-stock fisheries in an era of reconciliation: Indigenous-led salmon monitoring in British Columbia
Indigenous fisheries; salmon monitoring; British Columbia; Heiltsuk First Nation; Indigenous management; Pacific salmon
Wild salmon are central to food security, cultural identity, and livelihoods of coastal Indigenous communities. Yet ongoing inequities in governance, declining fish populations, and mixed-stock ocean fisheries may pose challenges for equitable access between Indigenous fishers and other non-Indigenous fishers. We sought to understand current perceptions among Hailzaqv (Heiltsuk) fishers towards salmon fisheries and their management. We conducted dockside surveys with both Hailzaqv fishers and sport fishers, and in-depth interviews with Hailzaqv fishers, community members, and natural resource managers. From these surveys and interviews we quantified satisfaction among both food, social, and ceremonial fishers and visiting recreational fishers with the current salmon fishery and associated social-ecological drivers, and characterized perceptions among Hailzaqv people of salmon fisheries and management. Second, we synthesized community perceptions of the revitalization of terminal, communally run salmon fisheries within Hailzaqv territory as a tool for their future salmon management. Finally, we elicited information from Hailzaqv fishers about the barriers people in their community currently face in accessing salmon fisheries. Our findings suggest that low salmon abundance, increased fishing competition, and high costs associated with participation in marine mixed-stock fisheries currently hinder access and equity for Hailzaqv fishers. This community-based research can help strengthen local, Indigenous-led management of salmon into the future. DOI
83. Sweeney-Bergen, EK; Macintyre, D; Moore, JW. (2021) Ontogenetic habitat shifts and vulnerability: lake-outlet-spawning sockeye salmon (Oncorhynchus nerka) sensitivity to habitat connectivity and hydrologic change.Environ. Biol. Fishes 104: 383-399 Ontogenetic habitat shifts and vulnerability: lake-outlet-spawning sockeye salmon (Oncorhynchus nerka) sensitivity to habitat connectivity and hydrologic change
Salmon; Life history; Habitat; Migration; Ontogeny
Sockeye salmon that spawn downstream of rearing lakes are an important example of the challenges faced by organisms with complex life histories requiring connectivity in aquatic habitat complexes. Specifically, newly emerged juvenile sockeye salmon must migrate upstream, against the flow of water, if they are to reach lake rearing habitat. Here, we examine the spatial and temporal dynamics of the water velocity landscape and juvenile sockeye salmon movement and condition at increasing distances downstream from the lake outlet of an important sockeye salmon system, the Babine Lake of British Columbia, one of Canada's largest and most important sockeye salmon rearing lakes. The results of this study indicate that (i) there were seasonal and spatial patterns of water velocities that exceed the ability of juveniles to swim upstream to lake rearing habitat, (ii) higher water discharge was associated with more velocity barriers and potentially with less upstream movement of juveniles, and (iii) juveniles rearing in the lake obtained larger sizes (30% longer and 150% heavier) than those in downstream river habitats. Multiple processes that may be influencing these patterns could include more abundant food resources, lower metabolic demands, or size-selective immigration, emigration, or mortality among habitats. Years and seasons with high discharge may temporarily create one-way, downstream transport routes at lake outlets. Long-term changes in hydrology, perhaps driven by climate variability or land-use change, may control the degree to which lake outlets function as bidirectional travel corridors or one-way travel routes for young sockeye salmon. DOI
82. Wilson, KL; Bailey, CJ; Davies, TD; Moore, JW. (2021) Marine and freshwater regime changes impact a community of migratory Pacific salmonids in decline.Glob. Change Biol.Marine and freshwater regime changes impact a community of migratory Pacific salmonids in decline
Bayesian; ecosystem change; fisheries; population dynamics; salmon; time-series; watersheds
Marine and freshwater ecosystems are increasingly at risk of large and cascading changes from multiple human activities (termed "regime shifts"), which can impact population productivity, resilience, and ecosystem structure. Pacific salmon exhibit persistent and large fluctuations in their population dynamics driven by combinations of intrinsic (e.g., density dependence) and extrinsic factors (e.g., ecosystem changes, species interactions). In recent years, many Pacific salmon have declined due to regime shifts but clear understanding of the processes driving these changes remains elusive. Here, we unpacked the role of density dependence, ecosystem trends, and stochasticity on productivity regimes for a community of five anadromous Pacific salmonids (Steelhead, Coho Salmon, Pink Salmon, Dolly Varden, and Coastal Cutthroat Trout) across a rich 40-year time-series. We used a Bayesian multivariate state-space model to examine whether productivity shifts had similarly occurred across the community and explored marine or freshwater changes associated with those shifts. Overall, we identified three productivity regimes: an early regime (1976-1990), a compensatory regime (1991-2009), and a declining regime (since 2010) where large declines were observed for Steelhead, Dolly Varden, and Cutthroat Trout, intermediate declines in Coho and no change in Pink Salmon. These regime changes were associated with multiple cumulative effects across the salmon life cycle. For example, increased seal densities and ocean competition were associated with lower adult marine survival in Steelhead. Watershed logging also intensified over the past 40 years and was associated with (all else equal) >= 97% declines in freshwater productivity for Steelhead, Cutthroat, and Coho. For Steelhead, marine and freshwater dynamics played approximately equal roles in explaining trends in total productivity. Collectively, these changing environments limited juvenile production and lowered future adult returns. These results reveal how changes in freshwater and marine environments can jointly shape population dynamics among ecological communities, like Pacific salmon, with cascading consequences to their resilience. DOI PubMed
81. Wilson, SM; Buehrens, TW; Fisher, JL; Wilson, KL; Moore, JW. (2021) Phenological mismatch, carryover effects, and marine survival in a wild steelhead trout Oncorhynchus mykiss population.Prog. Oceanogr. 193 Phenological mismatch, carryover effects, and marine survival in a wild steelhead trout Oncorhynchus mykiss population
Match; mismatch hypothesis; Pacific salmon; Phenology; Ocean survival; Biological spring transition date; Zooplankton; Migrations
Climate-driven changes in the oceans, such as shifts in prey timing and abundance, could influence variability in population productivity of marine fishes. For example, according to the match/mismatch hypothesis, the temporal matching of the young salmon outmigration from freshwater to the ocean relative to the timing of availability of their prey could influence their marine survival. Indeed, understanding patterns and processes of marine survival is particularly pressing in many salmon and steelhead trout populations due to recent declines. To determine whether phenological mismatches between juvenile salmonids and their prey could contribute to low ocean survival, we analyzed the migration timing and ocean survival of 22,116 tagged juvenile steelhead trout Oncorhynchus mykiss over 12 years from the Wind River, Washington State, USA. We used a Bayesian multilevel modelling approach with variable selection to assess how survival was associated with body size, river exit date, the biological spring transition date (the day when northern zooplankton first appeared in the coastal region near the Columbia River estuary), and the degree of mismatch (the effect of the interaction between individual outmigration timing and biological spring transition date). The variables with the highest probability of contributing to individual survival were fish size (100%), river exit date (99%), the interaction between year and river exit date (91%), and the biological spring transition date (64%). Fish that were larger than average at outmigration had higher ocean survival, providing further evidence that freshwater growing conditions have carryover effects on marine survival. Years with greater annual phenological mismatches such as those years with late biological spring transition dates (i.e., occurring after June 1st), or warm sea surface temperatures, had sufficiently low marine survival to compromise recovery goals. Substantial intra-annual variation in outmigration timing buffered the population from inter-annual variation in optimal outmigration timing. Collectively these findings indicate that freshwater growing conditions, migration timing, and the timing of highquality food availability in the nearshore coastal environment work in concert to influence individual survival and annual smolt-to-adult returns. DOI
80. Wilson, SM; Robinson, KA; Gutzmann, S; Moore, JW; Patterson, DA. (2021) Limits on performance and survival of juvenile sockeye salmon (Oncorhynchus nerka) during food deprivation: a laboratory-based study.Conserv. Physiol. 9 Limits on performance and survival of juvenile sockeye salmon (Oncorhynchus nerka) during food deprivation: a laboratory-based study
Carryover effects; condition factor; energy density; migration; sockeye salmon; survival; swim performance
Long-distance migrations can be energetically demanding and can represent phases of high mortality. Understanding relationships between body condition and migratory performance can help illuminate the challenges and vulnerabilities of migratory species. Juvenile anadromous sockeye salmon (Oncorhynchus nerka) may migrate over 1000 km from their freshwater nursery habitats to estuary and ocean feeding grounds. During the period corresponding to the seaward migration of sockeye salmon, we held smolts in the laboratory to ask the following: (i) Does non-feeding migration duration influence prolonged swim performance and survival? (ii) What are the relationships between individual body condition and swim performance and survival? Wild sockeye salmon were intercepted during their migration and held without food for up to 61 days to represent the non-feeding freshwater migration and the extremes of poor estuary habitat. We conducted 40 sets of prolonged swim trials on 319 fish from 3 treatment groups that represented entrance to the marine environment on (i) an average,(ii) a delayed and (iii) a severely delayed migration schedule. Experimentally controlled freshwater migration duration did not impact swim performance or survival. Swim performance decreased concomitant with condition factor, where smolts with a Fulton's condition factor of <0.69 were less likely (<50% probability) to complete the swim test (90 min swim test, at similar to 0.50 m/s). Survival of salmon smolts in the laboratory was less likely at energy densities of less than 3.47 MJ/kg. Swim performance decreased much sooner than survival, suggesting that swim performance, and therefore condition factor, may be a good indicator of survival of migratory smolts, as fish with reduced swim performance will likely be predated. These two relationships, one more ecologically relevant and one more clinical, help reveal the limits of long-distance migration for juvenile salmon and can be used to determine population-specific starvation risk associated with various freshwater and marine habitat conditions. DOI PubMed
79. Atlas, WI; Selbie, DT; Holt, CA; Cox-Rogers, S; Carr-Harris, C; Pitman, KJ; Moore, JW. (2020) Landscape and biophysical controls of lake productivity to inform evaluation of sockeye salmon (Oncorhynchus nerka) populations in data-limited regions.Limnol. Oceanogr.Landscape and biophysical controls of lake productivity to inform evaluation of sockeye salmon (Oncorhynchus nerka) populations in data-limited regions
Landscape models are increasingly used to classify and predict the structure and productivity of data-limited aquatic ecosystems. One such suite of ecosystems is on the remote North and Central Coast (NCC) of British Columbia, where sockeye salmon (Oncorhynchus nerka) rear in more than 150 lakes. Given their remoteness and limited resources for assessment, limnological and population monitoring in many of these lakes has been periodic or absent, limiting understanding of the status of populations and their habitats. Lake photosynthetic rate (PR) estimates are foundational to models of sockeye salmon nursery lake productive capacity. Using data from 61 lakes across the NCC, we compared a suite of landscape and lake variables in an information theoretic framework producing a set of models relating these characteristics to lake PR. A categorical variable related to lake biogeochemistry-whether a lake is humic stained, clear, or glacially turbid-was the most important variable predicting lake PR and was included in all models. Lake surface area relative to upstream catchment size and lake perimeter-to-surface-area ratio were also important, with smaller upstream catchments yielding higher production, and high shoreline complexity correlated with lower productivity as measured by limnetic PR. Model-averaged predictions of PR from the four models with the lowest residual error were created for 96 lakes currently lacking limnological assessments. These landscape models represent a valuable starting point for evaluating lake-specific carrying capacities for data-poor sockeye salmon populations under Canada's Wild Salmon Policy. DOI
78. Bailey, CJ; Moore, JW. (2020) Resource pulses increase the diversity of successful competitors in a multi-species stream fish assemblage.Ecosphere 11 Resource pulses increase the diversity of successful competitors in a multi-species stream fish assemblage
coho salmon; competition; functional response; resource pulse; salmon subsidy; sculpins; steelhead trout; stream fishes
Food resources are often patchily distributed through space and time and are classified as resource pulses when hyperabundant. Resource pulses can benefit growth, reproduction, and abundance of various consumers. Yet, it is relatively unknown how such resources are partitioned among competing consumers and how this is influenced by the magnitude of the pulse. Here, we examined how the magnitude of a pulsed resource influences resource partitioning among diverse sizes and species of consumers in a natural setting over small spatial and temporal scales. We focused on salmon egg subsidies to stream fish consumers. We experimentally added different quantities of pink salmon eggs to five meter long experimental stream sections. Egg additions spanned three orders of magnitude from 6 to 3575 eggs. Stream fish (egg consumers) were captured and gastric lavaged at each experimental section to determine how many eggs each individual fish consumed. We modeled taxon-specific individual egg consumption as a function of egg availability, individual mass, community composition, number of competitors, and stream velocity using hurdle models in a Bayesian framework. We found that there were diminishing returns for increasing egg abundance increasing egg consumption (i.e., type II functional response) for individual size classes of fish, but that higher egg numbers were needed to benefit diverse consumers. Top models indicated that egg availability and individual fish characteristics (size and taxon) drove egg consumption, while community characteristics (species composition and number of competitors) were not supported. Our results suggest that resource pulses can provide rare opportunities for less dominant sizes and species of fish to consume abundant resources. The current paradigm in the stream fish literature suggests that stream fish communities are structured by dominance hierarchies; however, dominance hierarchies may be less influential where pulsed resources comprise a large portion of the resource base. DOI
77. Hodgson, EE; Hovel, RA; Ward, EJ; Lord, S; Moore, JW. (2020) Migratory diversity in an Arctic fish supporting subsistence harvest.Biol. Conserv. 248 Migratory diversity in an Arctic fish supporting subsistence harvest
Broad whitefish; Otolith microchemistry; Vulnerability; Spatial ecology; Conservation; Hidden Markov model; Strontium isotope
Arctic regions are warming more than twice as quickly as other parts of the globe, threatening Arctic fish and wildlife and the human communities that rely on them. Assessing species' vulnerability to this change requires understanding their life histories and ecology, including movement patterns and habitat use. However, this information has not been documented for many Arctic species, which may not follow predicable movements in these vast and changing landscapes. In the Gwich'in Settlement Area of western Canadian Arctic, one such species is luk dagaii (in Gwich'in) or broad whitefish (Coregonus nasus). This species is the most important food fish for the Gwich'in Peoples of the region. We present results from a collaborative community-based research program established to build research capacity and address pressing research questions. Using otoliths extracted from fish caught by community monitors along the Peel River, we investigated migratory patterns using the isotopic ratio, Sr-87/Sr-86. Applying a hidden Markov model to the otolith laser ablation transects, we explored emergent model states and linked them to regions of the watershed. Across and within individuals, fish occupied the ocean and three different identified freshwater locations; however, while all fish were captured in the Peel River, none expressed an otolith signature that would suggest they grew there. Across individuals, we found large variability in migratory patterns, suggesting that migrations are not obligate and that individual fish utilize the watershed very differently. This diversity may buffer whitefish and reliant human communities against change, but indicates dependence on a large, intact watershed. DOI
76. Hodgson, EE; Wilson, SM; Moore, JW. (2020) Changing estuaries and impacts on juvenile salmon: A systematic review.Glob. Change Biol.Changing estuaries and impacts on juvenile salmon: A systematic review
environmental impact assessment; estuary impacts; salmon; smolt; stressors
Estuaries are productive ecosystems providing important habitat for a diversity of species, yet they also experience intense levels of anthropogenic development. To inform decision-making, it is essential to understand the pathways of impacts of particular human activities, especially those that affect species such as salmon, which have high ecological, social-cultural and economic values. Salmon systems provide an opportunity to build from the substantial body of research on responses to estuary developments and take stock of what is known. We conducted a systematic English-language literature review on the responses of juvenile salmon to anthropogenic activities in estuaries and nearshore areas asking: what has been studied, where are the major knowledge gaps and how do stressors affect salmon? We found a substantial body of research (n = 167 studies; 1,369 comparative tests) to help understand responses of juvenile salmon to 24 activities and their 14 stressors. Across studies, 82% of the research was conducted in the eastern Pacific (Oregon and Washington, USA and British Columbia, Canada) showing a limited geographical scope. Using a semiquantitative approach to summarize the literature, including a weight-of-evidence metric, we found a range of results from low to moderate-high confidence in the consequences of the stressors. For example, we found moderate-high confidence in the negative impacts of pollutants and sea lice and moderate confidence in negative impacts from connectivity loss and changes in flow. Our results suggest that overall, multiple anthropogenic activities cause negative impacts across ecological scales. However, our results also reveal knowledge gaps resulting from minimal research on particular species (e.g. sockeye salmon), regions (e.g. Atlantic) or stressors (e.g. entrainment) that would be expedient areas for future research. With estuaries acting as a nexus of biological and societal importance and hotspots of ongoing development, the insights gained here can contribute to informed decision-making. DOI PubMed
75. Pitman, KJ; Moore, JW; Sloat, MR; Beaudreau, AH; Bidlack, A; Brenner, RE; Hood, EW; Pess, GR; Mantua, NJ; Milner, AM; Radic, V; Reeves, GH; Schindler, DE; Whited, DC. (2020) Glacier Retreat and Pacific Salmon.Bioscience 70: 220-236 Glacier Retreat and Pacific Salmon
climate change; glaciers; Oncorhynchus; Pacific salmon; watershed
Glaciers have shaped past and present habitats for Pacific salmon (Oncorhynchus spp.) in North America. During the last glacial maximum, approximately 45% of the current North American range of Pacific salmon was covered in ice. Currently, most salmon habitat occurs in watersheds in which glacier ice is present and retreating. This synthesis examines the multiple ways that glacier retreat can influence aquatic ecosystems through the lens of Pacific salmon life cycles. We predict that the coming decades will result in areas in which salmon populations will be challenged by diminished water flows and elevated water temperatures, areas in which salmon productivity will be enhanced as downstream habitat suitability increases, and areas in which new river and lake habitat will be formed that can be colonized by anadromous salmon. Effective conservation and management of salmon habitat and populations should consider the impacts of glacier retreat and other sources of ecosystem change. DOI PubMed
72. Vierros, MK; Harrison, AL; Sloat, MR; Crespo, GO; Moore, JW; Dunn, DC; Ota, Y; Cisneros-Montemayor, AM; Shillinger, GL; Watson, TK; Govan, H. (2020) Considering Indigenous Peoples and local communities in governance of the global ocean commons.Mar. Pol. 119 Considering Indigenous Peoples and local communities in governance of the global ocean commons
The United Nations are currently negotiating a new international legally-binding instrument to govern the global ocean commons, a vast area beyond national jurisdiction (ABNJ) owned by everyone but not cared for by any single entity. Indigenous Peoples and local communities (IPLCs) have been underrepresented in the debate about governance of ABNJ despite their internationally recognized rights and their role as custodians of many globally-significant migratory species that travel between coasts and high seas. Here we use examples of active transboundary connectivity by migratory species as case studies to highlight the relevance of IPLCs on islands, coasts and beyond to the governance of the global ocean commons, and make a case for their essential and beneficial inclusion in it. Many migratory species are culturally and economically important to IPLCs, who are frequently the first to suffer if these species are overexploited or decline due to inadequate management in ABNJ. Four case studies (Pacific salmon, Marine Turtles, Black-footed and Laysan Albatrosses, Northern fur seal) illustrate knowledge, innovations and practices of IPLCs that have global importance in informing strategies for conservation, sustainable and equitable use of marine species in general. IPLCs can contribute to enriching the diversity of approaches and solutions, and by elaborating on principles directly relevant for governance of ABNJ within the UN process and beyond. DOI
71. Walsh, JC; Connors, K; Hertz, E; Kehoe, L; Martin, TG; Connors, B; Bradford, MJ; Freshwater, C; Frid, A; Halverson, J; Moore, JW; Price, MHH; Reynolds, JD. (2020) Prioritizing conservation actions for Pacific salmon in Canada.J. Appl. Ecol.Prioritizing conservation actions for Pacific salmon in Canada
conservation planning; decision-support tool; Indigenous knowledge; Pacific salmon; Priority Threat Management; recovery planning; stream restoration; Wild Salmon Policy
Current investment in conservation is insufficient to adequately protect and recover all ecosystems and species. The challenge of allocating limited funds is acute for Pacific salmon Oncorhynchus spp. in Canada, which lack a strategic approach to ensure that resources are spent on actions most likely to cost-effectively recover diminished populations. We applied the Priority Threat Management framework to prioritize strategies most likely to maximize the number of thriving Pacific salmon populations on the Central Coast of British Columbia, Canada. These included 79 genetically, ecologically and spatially distinct population groups called conservation units (CUs) for five salmon species. This region has high salmon biodiversity and spans the territories of four First Nations: the Heiltsuk, Nuxalk, Kitasoo/Xai'xais and Wuikinuxv. Using structured expert elicitation of Indigenous and other experts, we quantified the estimated benefits, costs and feasibility of implementing 10 strategies. Under a business-as-usual scenario (i.e. no additional investments in salmon conservation or management), experts predicted that only one in four CUs would have >50% chance of achieving a thriving status within 20 years. Limiting future industrial development in salmon habitats, which was predicted to safeguard CUs from future declines, was identified as the most cost-effective strategy. Investment in three strategies: (a) removal of artificial barriers to fish migration, (b) watershed protection and (c) stream restoration-at 11.3M CAD per year-was predicted to result in nearly half (34 of 79) of the CUs having a >60% chance of meeting the conservation objective. If all conservation strategies were implemented, experts estimated a >50% probability of achieving a thriving status for 78 of 79 CUs, at an annual cost of 17.3M CAD. However, even with the implementation of all strategies, most sockeye salmon CUs were unlikely to achieve higher probability targets of reaching the objective. Policy implications. We illustrate how Priority Threat Management can incorporate the perspectives and expertise of Indigenous peoples and other experts to prioritize conservation strategies based on their cost, benefit and feasibility. Implementation of this framework can help safeguard and recover Pacific salmon in Canada, and could also be used to prioritize actions for other conservation issues globally. DOI
70. Bailey, CJ; Andersson, LC; Arbeider, M; Bradford, K; Moore, JW. (2019) Salmon egg subsidies and interference competition among stream fishes.Environ. Biol. Fishes 102: 915-926 Salmon egg subsidies and interference competition among stream fishes
Aggression; Fish community; Resource superabundance; Competitive interactions; Oncorhynchus sp
Resource availability may modulate interference interactions among competitors. For example, competition among stream fishes for drifting eggs from salmon (Oncorhynchus spp.) spawning events may be influenced by the availability of this energy-rich food source. This study used camera-based techniques to evaluate the effect of varied prey availability (i.e., pink salmon (O. gorbuscha) eggs) on rates of interference competition within natural stream fish communities at 10 sites. Aggressive interactions were quantified across different levels of egg additions, ranging from 6 to 3575 O. gorbuscha eggs, at 10 sites on the Keogh River, British Columbia, Canada. There were fewer aggressive interactions among salmonids (O. kisutch, O. mykiss, and O. clarkii clarkii) when there were more available eggs. Aggressive interaction rates were species-dependent; for example, the number of aggressive acts relative to null expectations based on abundances were highest in juvenile coho (O. kisutch) towards conspecifics. For some interactions, size of fish appeared to be a key factor as well. Thus, higher densities of spawning salmon in streams may provide sufficient prey resources in the form of eggs to temporarily decrease interference competition among stream fishes. DOI
68. Price, MHH; Connors, BM; Candy, JR; McIntosh, B; Beacham, TD; Moore, JW; Reynolds, JD. (2019) Genetics of century-old fish scales reveal population patterns of decline.Conserv. Lett.Genetics of century-old fish scales reveal population patterns of decline
conservation genetics; ecosystems; fisheries; historical ecology; population depletion; recovery; salmon; extinction risk; Skeena River
Conservation scientists rarely have the information required to understand changes in abundance over more than a few decades, even for important species like Pacific salmon. Such lack of historical information can underestimate the magnitude of decline for depressed populations. We applied genetic tools to a unique collection of 100-year-old salmon scales to reveal declines of 56%-99% in wild sockeye populations across Canada's second largest salmon watershed, the Skeena River. These analyses reveal century-long declines that are much greater than those based on modern era abundance data, which suggested that only 7 of 13 populations declined over the last five decades. Populations of larger-bodied fish have declined the most in abundance, likely because of size-selective commercial fisheries. Our findings illustrate how a deep historical perspective can expand our understanding of past abundances to a time before species incurred significant losses from fishing, and help inform conservation for diminished populations. DOI
67. Sharpe, C; Carr-Harris, C; Arbeider, M; Wilson, SM; Moore, JW. (2019) Estuary habitat associations for juvenile Pacific salmon and pelagic fish: Implications for coastal planning processes.Aquat. Conserv.-Mar. Freshw. Ecosyst. 29: 1636-1656 Estuary habitat associations for juvenile Pacific salmon and pelagic fish: Implications for coastal planning processes
environmental impact assessment; estuary; fish; habitat management; industry; Pacific herring; Hypomesus pretiosus
Assessment of risk from industrial developments often relies on simple habitat descriptions for focal species. However, simple habitat metrics may not be accurate predictors of locations that species actually use. Understanding the nature of habitat is particularly pressing for estuaries, as they are among the most degraded ecosystems globally but provide critical rearing habitat for many species, including Pacific salmon. Canadian environmental impact assessment approaches use simple habitat-type models to assess risk from developments and assume that different species of salmon rely on the same habitat. This study asked what combination of habitat type and biophysical covariates best predicted use of estuary habitat by juvenile salmon and two dominant small pelagic fish. Fish were sampled via purse seine throughout the Skeena River estuary (British Columbia, Canada) for 2 years across different habitat types (eelgrass, open water, sandy banks, and rocky shores). Simple habitat-type models were compared with models with more complex biophysical variables to predict the variability in relative abundance of juvenile Chinook (Oncorhynchus tshawytscha), coho (Oncorhynchus kisutch), and sockeye (Oncorhynchus nerka) salmon, along with pelagic fish species Pacific herring (Clupea pallasii) and surf smelt (Hypomesus pretiosus). The combination of variables that best predicted abundance differed across fish species. Pelagic fish were associated with near-shore sites, increased temperature (herring), and increased salinity (smelt). Juvenile coho and sockeye salmon (but not Chinook), were more abundant in higher turbid waters. Chinook and sockeye salmon used eelgrass habitat more frequently than other habitat types, whereas coho salmon were more abundant in areas with high macroalgae cover. Models with these variables had greater predictive power than those using habitat type alone for juvenile salmon. Simple classifications of estuary habitat currently used in environmental risk assessment may not reflect the complex nature of fish-habitat associations. Understanding biophysical factors associated with estuary fish abundance can inform management of estuary habitat to support their nursery function for important fish. DOI
66. Bailey, CJ; Braun, DC; McCubbing, D; Reynolds, JD; Ward, B; Davies, TD; Moore, JW. (2018) The roles of extrinsic and intrinsic factors in the freshwater life-history dynamics of a migratory salmonid.Ecosphere 9 The roles of extrinsic and intrinsic factors in the freshwater life-history dynamics of a migratory salmonid
anadromy; artificial nutrient addition; fisheries; life-history diversity; long-term study; marine-derived nutrients; steelhead
Key life-cycle transitions, such as metamorphosis or migration, can be altered by a variety of external factors, such as climate variation, strong species interactions, and management intervention, or modulated by density dependence. Given that these life-history transitions can influence population dynamics, understanding the simultaneous effects of intrinsic and extrinsic controls on life-history expression is particularly relevant for species of management or conservation importance. Here, we examined how life histories of steelhead (Oncorhynchus mykiss) are affected by weather, pink salmon abundance (Oncorhynchus gorbuscha), experimental nutrient addition, and density-dependent processes. We tested for impacts on the size of steelhead smolts (juveniles migrating to the sea), as well as their age and abundance across four decades in the Keogh River, British Columbia, Canada. Larger steelhead smolts were associated with warmer years and artificial nutrient addition. In addition, higher pink salmon abundance and artificial nutrient addition correlated with juvenile steelhead migrating at younger ages. While density dependence appeared to be the primary factor regulating the abundance of steelhead smolts, nutrient addition and temperature were positively and negatively associated with smolt production, respectively, prior to 1991, and pink salmon spawning abundance was positively associated with smolt production after 1990. Thus, this study provides evidence that the temporal dynamics of one species of salmon is linked to the juvenile life history of co-occurring steelhead. A complex interplay of species interactions, nutrient subsidies, density dependence, and climatic variation can control the life-history expression of species with complex life cycles. DOI
65. Carr-Harris, CN; Moore, JW; Gottesfeld, AS; Gordon, JA; Shepert, WM; Henry, JDJ; Russell, HJ; Helin, WNB; Doolan, DJ; Beacham, TD. (2018) Phenological Diversity of Salmon Smolt Migration Timing within a Large Watershed.Trans. Am. Fish. Soc. 147 Phenological Diversity of Salmon Smolt Migration Timing within a Large Watershed
Although there is growing concern that climate change might drive phenological mismatches between predators and prey, it is possible that within- and among-species phenological variation provides resilience against such a mismatch. One key life history event that may be vulnerable to climate-induced mismatch is the seaward migration of juvenile salmon relative to the spring bloom of their marine zooplankton prey. Here, we quantified phenological diversity of out-migration timing among salmon populations within a large watershed and its implications for climate mismatches with marine zooplankton. Specifically, we sampled juvenile Sockeye Salmon Oncorhynchus nerka throughout the spring and early summer in the estuary of the Skeena River, a vast watershed with numerous locally adapted salmon populations that support commercial, recreational, and First Nations fisheries, and we used genetic stock identification to link the fish to their population of origin. We found that Sockeye Salmon were migrating through the estuary for more than 50d, with peak emigration for different populations varying by over 5weeks. The out-migration timing of specific populations was related to geographic factors, including elevation of the rearing lake and theriver distance between individual rearing lakes and the estuary, with different populations arriving 1.5d later for every 100m of elevation or 3d later for every 100km of river distance. Concurrent with sampling, we quantified the estuarine prey of juvenile Sockeye Salmon; zooplankton species composition and abundance varied throughout the smolt migration period, and the different salmon populations encountered different prey abundances upon ocean entry. Together, these results indicate underappreciated phenological diversity in this harvested metapopulation, which may contribute to response diversity and metapopulation-level resilience to climate change. DOI
63. Seifert, RE; Moore, JW. (2018) Floodgate Operations and Fish Communities in Tidal Creeks of the Lower Fraser River (British Columbia, Canada).Estuaries Coasts 41: 1206-1221 Floodgate Operations and Fish Communities in Tidal Creeks of the Lower Fraser River (British Columbia, Canada)
Flood mitigation; Fish; Tide gates; Impoundment; Connectivity; Salmon
Tidal creeks in large coastal deltas can be important habitat for fish but are often highly modified by human activities. Connectivity between tributary creeks and mainstem channels is often constrained by structures such as dikes and floodgates, designed to protect urban and agricultural areas from flooding. While they play important roles in flood mitigation, floodgates can diminish habitat quality and block fish from accessing tidal creeks. It is likely that floodgates differ in their operations and may consequently open for different amounts of time; however, floodgate operations and their effects are not well quantified. We asked the question: how does the mechanical functioning of these floodgates affect fish communities in tidal creeks? We used time-lapse cameras and quantified the timing of gate openings for 22 tributaries of the Lower Fraser River in British Columbia, Canada, and related these operational data to differences in fish communities above and below floodgates. Floodgate operations varied substantially, with some floodgates opening daily while others opened less than 20% of the day, on average. Sites with floodgates that seldom opened were associated with greater differences in fish communities and with reduced upstream native species richness by about one species on average. Where floodgates opened infrequently, we also found lower upstream dissolved oxygen concentrations than at sites where floodgates opened for longer periods of time. Thus, floodgate operations can influence fish communities as well as water quality. These data indicate a large scope for improving floodgate operations for connectivity. DOI
62. Brewitt, KS; Danner, EM; Moore, JW. (2017) Hot eats and cool creeks: juvenile Pacific salmonids use mainstem prey while in thermal refuges.Can. J. Fish. Aquat. Sci. 74: 1588-1602 Hot eats and cool creeks: juvenile Pacific salmonids use mainstem prey while in thermal refuges
Thermal refuges form important habitat for cold-water fishes in the face of rising temperatures. As fish become concentrated in refuges, food resources may become depleted. In this study, we used invertebrate drift sampling and fish density surveys to quantify potential in-refuge food limitation, temperature-sensitive radio-tagging studies to quantify thermal habitat use, and isotopic analyses to determine diet sources for juvenile Pacific salmonids using thermal refuges in California's Klamath River. Juvenile salmonids using refuges formed by tributary junctions with the mainstem river obtained the majority (range = 47%-97%) of their diet from mainstem prey sources. Mean steelhead (Oncorhynchus mykiss) body temperatures were significantly cooler (similar to 3.5 degrees C) than diet-inferred foraging temperatures. Thus, while fish seek cooler habitat for physiological benefits, they rely primarily on mainstem prey. Moreover, consistently high densities of fish in refuges (mean = 3.5 fish.m(-2)) could lead to density-dependent food limitation. Thus, mobile consumers like fish can exploit existing heterogeneity associated with cold-water refuges by gaining thermal benefits from a food-limited cold-water habitat while deriving the majority of their prey from the warm mainstem river. DOI
61. Chezik, KA; Anderson, SC; Moore, JW. (2017) River networks dampen long-term hydrological signals of climate change.Geophys. Res. Lett. 44: 7256-7264 River networks dampen long-term hydrological signals of climate change
River networks may dampen local hydrologic signals of climate change through the aggregation of upstream climate portfolio assets. Here we examine this hypothesis using flow and climate trend estimates (1970-2007) at 55 hydrometric gauge stations and across their contributing watersheds' within the Fraser River basin in British Columbia, Canada. Using a null hypothesis framework, we compared our observed attenuation of river flow trends as a function of increasing area and climate trend diversity, with null-simulated estimates to gauge the likelihood and strength of our observations. We found the Fraser River reduced variability in downstream long-term discharge by >91%, with >3.1 times the attenuation than would be expected under null simulation. Although the strength of dampening varied seasonally, our findings indicate that large free-flowing rivers offer a powerful and largely unappreciated process of climate change mitigation. River networks that integrate a diverse climate portfolio can dampen local extremes and offer climate change relief to riverine biota. DOI
60. Hussey, NE; DiBattista, JD; Moore, JW; Ward, EJ; Fisk, AT; Kessel, S; Guttridge, TL; Feldheim, KA; Franks, BR; Gruber, SH; Weideli, OC; Chapman, DD. (2017) Risky business for a juvenile marine predator? Testing the influence of foraging strategies on size and growth rate under natural conditions.Proceedings of the Royal Society B-Biological Sciences 284 Risky business for a juvenile marine predator? Testing the influence of foraging strategies on size and growth rate under natural conditions
food web; lemon shark; life history; natural selection; predation risk; stable isotopes
Mechanisms driving selection of body size and growth rate in wild marine vertebrates are poorly understood, thus limiting knowledge of their fitness costs at ecological, physiological and genetic scales. Here, we indirectly tested whether selection for size-related traits of juvenile sharks that inhabit a nursery hosting two dichotomous habitats, protected mangroves (low predation risk) and exposed seagrass beds (high predation risk), is influenced by their foraging behaviour. Juvenile sharks displayed a continuum of foraging strategies between mangrove and seagrass areas, with some individuals preferentially feeding in one habitat over another. Foraging habitat was correlated with growth rate, whereby slower growing, smaller individuals fed predominantly in sheltered mangroves, whereas larger, faster growing animals fed over exposed seagrass. Concomitantly, tracked juveniles undertook variable movement behaviours across both the low and high predation risk habitat. These data provide supporting evidence for the hypothesis that directional selection favouring smaller size and slower growth rate, both heritable traits in this shark population, may be driven by variability in foraging behaviour and predation risk. Such evolutionary pathways may be critical to adaptation within predator-driven marine ecosystems. DOI
59.Moore, JW; Olden, JD. (2017) Response diversity, nonnative species, and disassembly rules buffer freshwater ecosystem processes from anthropogenic change.Glob. Change Biol. 23: 1871-1880 Response diversity, nonnative species, and disassembly rules buffer freshwater ecosystem processes from anthropogenic change
biodiversity; ecosystem function; resilience; stream; urbanization
Integrating knowledge of environmental degradation, biodiversity change, and ecosystem processes across large spatial scales remains a key challenge to illuminating the resilience of earth's systems. There is now a growing realization that the manner in which communities will respond to anthropogenic impacts will ultimately control the ecosystem consequences. Here, we examine the response of freshwater fishes and their nutrient excretion -a key ecosystem process that can control aquatic productivity -to human land development across the contiguous United States. By linking a continental-scale dataset of 533 fish species from 8100 stream locations with species functional traits, nutrient excretion, and land remote sensing, we present four key findings. First, we provide the first geographic footprint of nutrient excretion by freshwater fishes across the United States and reveal distinct local-and continental-scale heterogeneity in community excretion rates. Second, fish species exhibited substantial response diversity in their sensitivity to land development; for native species, the more tolerant species were also the species contributing greater ecosystem function in terms of nutrient excretion. Third, by modeling increased land-use change and resultant shifts in fish community composition, land development is estimated to decrease fish nutrient excretion in the majority (63%) of ecoregions. Fourth, the loss of nutrient excretion would be 28% greater if biodiversity loss was random or 84% greater if there were no nonnative species. Thus, ecosystem processes are sensitive to increased anthropogenic degradation but biotic communities provide multiple pathways for resistance and this resistance varies across space. DOI PubMed
58. Sergeant, CJ; Bellmore, R; McConnell, C; Moore, JW. (2017) High salmon density and low discharge create periodic hypoxia in coastal rivers.Ecosphere 8 High salmon density and low discharge create periodic hypoxia in coastal rivers
Alaska; bioenergetics; dissolved oxygen; ecosystem engineer; hatcheries; hypoxia; Pacific salmon; strays; subsidy-stress gradient; thermal regime
Dissolved oxygen (DO) is essential to the survival of almost all aquatic organisms. Here, we examine the possibility that abundant Pacific salmon (Oncorhynchus spp.) and low streamflow combine to create hypoxic events in coastal rivers. Using high-frequency DO time series from two similar watersheds in southeastern Alaska, we summarize DO regimes and the frequency of hypoxia in relationship to salmon density and stream discharge. We also employ a simulation model that links salmon oxygen respiration to DO dynamics and predicts combinations of salmon abundance, discharge, and water temperature that may result in hypoxia. In the Indian River, where DO was monitored hourly during the ice-free season from 2010 to 2015, DO levels decreased when salmon were present. In 2013, a year with extremely high spawning salmon densities, DO dropped to 1.7 mg/L and 16% saturation, well below lethal limits. In Sawmill Creek, where DO was monitored every six minutes across an upstream-downstream gradient during the 2015 spawning season, DO remained fully saturated upstream of spawning reaches, but declined markedly downstream to 2.9 mg/L and 26% saturation during spawning. Modeled DO dynamics in the Indian River closely tracked field observations. Model sensitivity analysis illustrates that low summertime river discharge is a precursor to salmon-induced oxygen depletion in our study systems. Our results provide compelling evidence that dense salmon populations and low discharge can trigger hypoxia, even in rivers with relatively cold thermal regimes. Although climate change modeling for southeastern Alaska predicts an increase in annual precipitation, snowfall in the winter and rainfall in the summer are likely to decrease, which would in turn decrease summertime discharge in rain-and snow-fed streams and potentially increase the frequency of hypoxia. Our model template can be adapted by resource managers and watershed stakeholders to create real-time predictive models of DO trends for individual streams. While preserving thermally suitable stream habitat for cold-water taxa facing climate change has become a land management priority, managers should also consider that some protected watersheds may still be at risk of increasingly frequent hypoxia due to human impacts such as water diversion and artificially abundant salmon populations caused by hatchery straying. DOI
57. Braun, DC; Moore, JW; Candy, J; Bailey, RE. (2016) Population diversity in salmon: linkages among response, genetic and life history diversity.Ecography 39: 317-328 Population diversity in salmon: linkages among response, genetic and life history diversity
Response diversity and asynchrony are important for stability and resilience of meta-populations, however little is known about the mechanisms that might drive such processes. In salmon populations, response diversity and asynchrony have been linked to the stability of their meta-populations and the fisheries that integrate across them. We examined how population diversity influenced response diversity and asynchrony in 42 populations of Chinook salmon from the Fraser River, British Columbia. We examined diversity in the survival responses to large-scale ocean climate variables for populations that differed in life history. Different life-histories responded differently to ocean environmental conditions. For instance, an increase of offshore temperature was associated with decreased survival for a population with ocean rearing juveniles but increased survival for a population with stream rearing juveniles. In a second analysis, we examined asynchrony in abundance between populations, which we then correlated with life history, spatial, and genetic diversity. Populations that were more genetically distant had the most different population dynamics. Collectively, these results suggest that fine-scale population diversity can contribute to the asynchrony and response diversity that underpins the stability of fisheries or metapopulation dynamics, and emphasize the need to manage and conserve this scale of population diversity. DOI
56.Moore, JW; Gordon, J; Carr-Harris, C; Gottesfeld, AS; Wilson, SM; Russell, JH. (2016) Assessing estuaries as stopover habitats for juvenile Pacific salmon.Mar. Ecol.-Prog. Ser. 559: 201-215 Assessing estuaries as stopover habitats for juvenile Pacific salmon
Anadromy; Bottleneck; Corridor; Early marine; Nursery habitat; Smolt; Stable isotope; Oncorhynchus
Habitats along migratory routes may provide key resources for migratory species (e.g. stopover habitat). For example, migratory juvenile salmon transit through estuaries on their way from freshwaters out to the ocean, but they may also reside and feed in these habitats. Here we examined the amount of time that juvenile salmon feed and reside in the estuary of the Skeena River (British Columbia, Canada), the second-largest salmon-bearing watershed in Canada. We implemented a novel application of stable isotopes of sulfur, carbon, and nitrogen as clocks to estimate the days since estuary entry. Salmon estuary residency varied across species; 25% of individuals spent at least 33, 22, 30, and 5 d in the estuary for Chinook Oncorhynchus tshawytscha, coho O. kisutch, pink O. gorbuscha, and sockeye salmon O. nerka, respectively. Larger pink and Chinook salmon resided in the estuary for longer durations, growing at an estimated 0.2 and 0.5 mm d(-1), respectively, evidence that estuary residency provides growth opportunities. A negative relationship between size and estuary residency in coho salmon suggests the potential existence of an estuary fry life history. Genetic stock assignment indicated that different populations of sockeye salmon may reside in the estuary for different amounts of time. Collectively, these results reveal that estuaries can represent stopover habitats for salmon, and that the extent varies across salmon species and populations. These data address a knowledge gap in assessment of environmental risks of proposed industrial developments. This study indicates the importance of considering the fundamental nature of habitats through which migratory species move. DOI
55. Nesbitt, HK; Moore, JW. (2016) Species and population diversity in Pacific salmon fisheries underpin indigenous food security.Journal of Applied Ecology 53: 1489-1499 Species and population diversity in Pacific salmon fisheries underpin indigenous food security
aboriginal; biodiversity; diversity-stability; First Nations; portfolio effect; rights and title; small-scale fisheries; subsistence; traditional; watershed management
1. Indigenous people arc considered to be among the most vulnerable to food insecurity and biodiversity loss. Biodiversity is cited as a key component of indigenous food security; however, quantitative examples of this linkage are limited. 2. We examined how species and population diversity influence the food security of indigenous fisheries for Pacific salmon (Oncorhynchus species). We compared two dimensions of food security- catch stability (interannual variability) and access (season length)- across a salmon diversity gradient for 21 fisheries on the Fraser River, Canada, over 30 years, using linear regression models. We used population diversity proxies derived from a range of existing measures because population-specific data were unavailable. 3. While both population and species diversity were generally associated with higher catch stability and temporal access, population diversity had a stronger signal. Fisheries with access to high species diversity had up to 1.4 times more stable catch than predicted by the portfolio effect and up to 1.2 times longer fishing seasons than fisheries with access to fewer species. Fisheries with access to high population diversity had up to 3.8 times more stable catch and three times longer seasons than fisheries with access to fewer populations. 4. Catch stability of Chinook Oncorhynchus tshawytschct and sockeye Oncorhynchus nerka fisheries was best explained by the number of populations and conservation units, respectively, that migrate past a fishery en route to spawning grounds. Similar population diversity metrics were important explanatory variables for season length of sockeye, pink Oncorhynchus god) uscha, coho Oncorhynchus kisutch and churn Oncorhynchus keta fisheries. 5. Synthesis and applications. We show an empirical example of how multiple scales of biodiversity support food security across a large watershed and suggest that protecting fine-scale salmon diversity will help promote food security for indigenous people. The scales of environmental assessments need to match the scales of the socio-ecological processes that will be affected by development. We illustrate that upstream projects that damage salmon habitat could degrade the food security of downstream indigenous fisheries, with implications to Canadian indigenous people and to watersheds around the world where migratory fishes support local fisheries. DOI
54. Phillis, CC; Moore, JW; Buoro, M; Hayes, SA; Garza, JC; Pearse, DE. (2016) Shifting Thresholds: Rapid Evolution of Migratory Life Histories in Steelhead/Rainbow Trout, Oncorhynchus mykiss.Journal of Heredity 107: 51-60 Shifting Thresholds: Rapid Evolution of Migratory Life Histories in Steelhead/Rainbow Trout, Oncorhynchus mykiss
alternative migratory tactics; anadromy; conditional strategy; contemporary evolution; partial migration; threshold traits
Expression of phenotypic plasticity depends on reaction norms adapted to historic selective regimes; anthropogenic changes in these selection regimes necessitate contemporary evolution or declines in productivity and possibly extinction. Adaptation of conditional strategies following a change in the selection regime requires evolution of either the environmentally influenced cue (e. g., size-at-age) or the state (e. g., size threshold) at which an individual switches between alternative tactics. Using a population of steelhead (Oncorhynchus mykiss) introduced above a barrier waterfall in 1910, we evaluate how the conditional strategy to migrate evolves in response to selection against migration. We created 9 families and 917 offspring from 14 parents collected from the above-and below-barrier populations. After 1 year of common garden-rearing above-barrier offspring were 11% smaller and 32% lighter than below-barrier offspring. Using a novel analytical approach, we estimate that the mean size at which above-barrier fish switch between the resident and migrant tactic is 43% larger than below-barrier fish. As a result, above-barrier fish were 26% less likely to express the migratory tactic. Our results demonstrate how rapid and opposing changes in size-at-age and threshold size contribute to the contemporary evolution of a conditional strategy and indicate that migratory barriers may elicit rapid evolution toward the resident life history on timescales relevant for conservation and management of conditionally migratory species. DOI
53. Scott, DC; Arbeider, M; Gordon, J; Moore, JW. (2016) Flood control structures in tidal creeks associated with reduction in nursery potential for native fishes and creation of hotspots for invasive species.Can. J. Fish. Aquat. Sci. 73: 1138-1148 Flood control structures in tidal creeks associated with reduction in nursery potential for native fishes and creation of hotspots for invasive species
Habitat connectivity is important for maintaining biodiversity and ecosystem processes yet globally is highly restricted by anthropogenic actions. Anthropogenic barriers are common in aquatic ecosystems; however, the effects of smallscale barriers such as floodgates have received relatively little study. Here we assess fish communities in ten tributaries over the spring-summer season of the lower Fraser River (British Columbia, Canada), five with floodgates and five reference sites without barriers, located primarily in agricultural land use areas. While the Fraser River supports the largest salmon runs in Canada, the lower Fraser river-floodplain ecosystem has numerous dikes and floodgates to protect valuable agricultural and urban developments. Floodgate presence was associated with reduced dissolved oxygen concentrations, threefold greater abundance of invasive fish species, and decreased abundances of five native fish species, including two salmon species. These findings provide evidence that floodgates decrease suitable habitat for native fishes, and become hotspots for non-native species. Given climate change, sea-level rise, and aging flood protection infrastructure, there is an opportunity to incorporate biodiversity considerations into further development or restoration of this infrastructure. DOI
52. Anderson, SC; Moore, JW; McClure, MM; Dulvy, NK; Cooper, AB. (2015) Portfolio conservation of metapopulations under climate change.Ecological Applications 25: 559-572 Portfolio conservation of metapopulations under climate change
biocomplexity; diversity-stability ecosystem-based management; Oncorhynchus spp; Pacific salmon; portfolio effect; prioritization; range contraction; response diversity; risk assessment; stochastic simulation
Climate change is likely to lead to increasing population variability and extinction risk. Theoretically, greater population diversity should buffer against rising climate variability, and this theory is often invoked as a reason for greater conservation. However, this has rarely been quantified. Here we show how a portfolio approach to managing population diversity can inform metapopulation conservation priorities in a changing world. We develop a salmon metapopulation model in which productivity is driven by spatially distributed thermal tolerance and patterns of short- and long-term climate change. We then implement spatial conservation scenarios that control population carrying capacities and evaluate the metapopulation portfolios as a financial manager might: along axes of conservation risk and return. We show that preserving a diversity of thermal tolerances minimizes risk, given environmental stochasticity, and ensures persistence, given long-term environmental change. When the thermal tolerances of populations are unknown, doubling the number of populations conserved may nearly halve expected metapopulation variability. However, this reduction in variability can come at the expense of long-term persistence if climate change increasingly restricts available habitat, forcing ecological managers to balance society's desire for short-term stability and long-term viability. Our findings suggest the importance of conserving the processes that promote thermal-tolerance diversity, such as genetic diversity, habitat heterogeneity, and natural disturbance regimes, and demonstrate that diverse natural portfolios may be critical for metapopulation conservation in the face of increasing climate variability and change. DOI
51. Atlas, WI; Buehrens, TW; McCubbing, DJF; Bison, R; Moore, JW. (2015) Implications of spatial contraction for density dependence and conservation in a depressed population of anadromous fish.Canadian Journal of Fisheries and Aquatic Sciences 72: 1682-1693 Implications of spatial contraction for density dependence and conservation in a depressed population of anadromous fish
Changes in density-independent mortality can alter the spatial extent of populations through patch extinction and colonization, and spatial contraction may alter population productivity and compensatory capacity. Here, we analyze a time series of steelhead (Oncorhynchus mykiss) abundance and examine the hypothesis that spatial contraction can decrease compensatory capacity. Over the last 20 years, steelhead in the Keogh River have declined by an order of magnitude because of a period of poor smolt-to-adult survival. Low abundance has been associated with more depressed production of out-migrating smolts than would be expected based on traditional models of compensatory dynamics. Patterns of juvenile density over time show changes in the spatial distribution of the population. We developed a spatially explicit population model to explore spatial structure and juvenile recruitment under varying marine survival. Results suggest that spatial contraction during a period of poor marine survival can strengthen density-dependent population regulation, reducing smolt production at the watershed scale. Our results highlight that spatial contraction can alter the fundamental density-dependent relationships that define population dynamics, recovery trajectories, and sustainable harvest levels of spatially structured populations. DOI
50. Carr-Harris, C; Gottesfeld, AS; Moore, JW. (2015) Juvenile Salmon Usage of the Skeena River Estuary.PLoS One 10 Juvenile Salmon Usage of the Skeena River Estuary
Migratory salmon transit estuary habitats on their way out to the ocean but this phase of their life cycle is more poorly understood than other phases. The estuaries of large river systems in particular may support many populations and several species of salmon that originate from throughout the upstream river. The Skeena River of British Columbia, Canada, is a large river system with high salmon population-and species-level diversity. The estuary of the Skeena River is under pressure from industrial development, with two gas liquefaction terminals and a potash loading facility in various stages of environmental review processes, providing motivation for understanding the usage of the estuary by juvenile salmon. We conducted a juvenile salmonid sampling program throughout the Skeena River estuary in 2007 and 2013 to investigate the spatial and temporal distribution of different species and populations of salmon. We captured six species of juvenile anadromous salmonids throughout the estuary in both years, and found that areas proposed for development support some of the highest abundances of some species of salmon. Specifically, the highest abundances of sockeye (both years), Chinook in 2007, and coho salmon in 2013 were captured in areas proposed for development. For example, juvenile sockeye salmon were 2-8 times more abundant in the proposed development areas. Genetic stock assignment demonstrated that the Chinook salmon and most of the sockeye salmon that were captured originated from throughout the Skeena watershed, while some sockeye salmon came from the Nass, Stikine, Southeast Alaska, and coastal systems on the northern and central coasts of British Columbia. These fish support extensive commercial, recreational, and First Nations fisheries throughout the Skeena River and beyond. Our results demonstrate that estuary habitats integrate species and population diversity of salmon, and that if proposed development negatively affects the salmon populations that use the estuary, then numerous fisheries would also be negatively affected. DOI PubMed
49. Favaro, C; Moore, JW. (2015) Fish assemblages and barriers in an urban stream network.Freshwater Science 34: 991-1005 Fish assemblages and barriers in an urban stream network
dendritic network; fish passage; riverscape; landscape
Stream networks are vulnerable to fragmentation. Anthropogenic structures, such as dams and culverts, can isolate stream branches, potentially interrupting longitudinal gradients of fish distribution. The effect of single barriers is well documented, but the effect of multiple barriers in small streams is not as well characterized. We used a landscape approach and spatially continuous sampling across 2 y to examine the influence of anthropogenic structures on fish distributions in an urban stream network. After accounting for spatial autocorrelation, we found higher Coastal Cutthroat Trout (Oncorhynchus clarki clarki) and lower Prickly Sculpin (Cottus asper) densities at locations up-than downstream of multiple culverts. Culverts had species-and year-specific stepwise effects that overrode fish distribution patterns attributable to environmental gradients. Prickly Sculpin exhibited strong spatial autocorrelation in both years, whereas Coho Salmon (Oncorhynchus kisutch) had negligible spatial autocorrelation in one year, a result indicating that spatial structure depends on species and year. Reaches did not have consistent fish densities across years and showed high temporal variability of fish or their habitats. Spatially continuous sampling captured gradients and heterogeneity in fish distributions and highlighted how anthropogenic structures alter these gradients. Our study also revealed which culverts had the strongest influences on fish densities throughout the stream network. The study design used can inform riverscape-management approaches, which are needed to conserve stream biodiversity effectively. DOI
48. Gordon, J; Arbeider, M; Scott, D; Wilson, SM; Moore, JW. (2015) When the Tides Don't Turn: Floodgates and Hypoxic Zones in the Lower Fraser River, British Columbia, Canada.Estuaries Coasts 38: 2337-2344 When the Tides Don't Turn: Floodgates and Hypoxic Zones in the Lower Fraser River, British Columbia, Canada
Agriculture; Coastal; Estuary; Fish; Impoundment; Sea level rise; Water quality
Floodgates are common flood control structures in coastal river systems, which allow tributary drainage into river main stems and decrease flooding risk of land upstream of diking systems. Floodgates have been shown to impact upstream aquatic habitats and alter organismal community structures in some systems by impounding water and acting as a physical barrier to migratory species; their impacts on water quality have been less well described. This study investigated water quality in tidal creeks with and without floodgates on the lower Fraser River, British Columbia, Canada. There are an estimated 500 floodgates in this region. Water quality measurements were taken upstream and downstream at three floodgate sites and three reference sites across a 10-day period in July/August. The average dissolved oxygen (DO) concentration upstream of floodgates was 2.47 mg/L and fell as low as 0.08 mg/L, which was significantly lower than the comparable region of reference sites (8.41 mg/L) during this sampling period. In contrast, the average DO concentration downstream of floodgates was 7.38 mg/L and in reference sites 8.35 mg/L. All DO concentration measurements upstream of floodgates in July and August fell below the 6-mg/L minimum set by the Canadian Council of Ministers of the Environment. These hypoxic zones extended at least 100 m upstream of floodgates. Thus, floodgates may be facilitating the occurrence of local hypoxic zones in summer months in these locations. Floodgate-induced hypoxia may not only cause local exclusion of sensitive native fishes but may also act as a chemical barrier that decreases connectivity among aquatic systems. Understanding these environmental impacts associated with floodgates can inform floodgate design and post-installation management, which is an increasingly important issue as coastal municipalities across the world deal with aging floodgate infrastructure and sea level rise. DOI
47.Moore, JW. (2015) Bidirectional connectivity in rivers and implications for watershed stability and management.Canadian Journal of Fisheries and Aquatic Sciences 72: 785-795 Bidirectional connectivity in rivers and implications for watershed stability and management
River networks are connected in both upstream and downstream directions on large spatial scales by movement of water, materials, and animals. Here I examine the implications of these linkages for the stability, productivity, and management of watersheds and their migratory fishes. I use simple simulations of watershed alteration to illustrate that degradation can erode the productivity and stability of both upstream and downstream fisheries. Through analysis of an existing global dataset on rivers, I found that larger rivers tend to be more fragmented than smaller rivers. I offer three challenges and opportunities for the future management of watersheds. First, given that human impacts can spread up and down rivers, there is a need to align the scales of impact assessments with the natural scale of river systems. Second, free-flowing rivers naturally dampen variability; thus, the conservation of connectivity, habitat, and biodiversity represents a key opportunity to sustain the processes that confer stability. Third, watersheds represent natural units of social-ecological systems; watershed governance would facilitate reciprocal feedbacks between people and ecosystems and enable more social-ecological resilience. DOI
46.Moore, JW; Beakes, MP; Nesbitt, HK; Yeakel, JD; Patterson, DA; Thompson, LA; Phillis, CC; Braun, DC; Favaro, C; Scott, D; Carr-Harris, C; Atlas, WI. (2015) Emergent stability in a large, free-flowing watershed.Ecology 96: 340-347 Emergent stability in a large, free-flowing watershed
biodiversity; dendritic network; Fraser River; British Columbia; Canada; natural defense system; portfolio effect; resilience; salmon; scale; watershed stability hypothesis
While it is widely recognized that financial stock portfolios can be stabilized through diverse investments, it is also possible that certain habitats can function as natural portfolios that stabilize ecosystem processes. Here we propose and examine the hypothesis that free-flowing river networks act as such portfolios and confer stability through their integration of upstream geological, hydrological, and biological diversity. We compiled a spatially (142 sites) and temporally (1980-present) extensive data set on fisheries, water flows, and temperatures, from sites within one of the largest watersheds in the world that remains without dams on its mainstem, the Fraser River, British Columbia, Canada. We found that larger catchments had more stable fisheries catches, water flows, and water temperatures than smaller catchments. These data provide evidence that free-flowing river networks function as hierarchically nested portfolios with stability as an emergent property. Thus, free-flowing river networks can represent a natural system for buffering variation and extreme events. DOI PubMed
45.Moore, JW; Carr-Harris, C; Gottesfeld, AS; MacIntyre, D; Radies, D; Cleveland, M; Barnes, C; Joseph, W; Williams, G; Gordon, J; Shepert, B. (2015) Selling First Nations down the river.Science 349: 596-596 Selling First Nations down the river
44. Beakes, MP; Moore, JW; Hayes, SA; Sogard, SM. (2014) Wildfire and the effects of shifting stream temperature on salmonids.Ecosphere 5 Wildfire and the effects of shifting stream temperature on salmonids
bioenergetics; climate change; disturbance; endangered species; fire; landscape ecology; riverscape; riparian
The frequency and magnitude of wildfires in North America have increased by four-fold over the last two decades. However, the impacts of wildfires on the thermal environments of freshwaters, and potential effects on coldwater fishes are incompletely understood. We examined the short-term effects of a wildfire on temperatures and Steelhead/Rainbow Trout (Oncorhynchus mykiss) bioenergetics and distribution in a California coastal stream. One year after the wildfire, mean daily stream temperatures were elevated by up to 0.6 degrees C in burned compared to unburned pools. Among burned pools, light flux explained over 85% of the variation in altered stream temperatures, and 76% of the variation in light flux was explained by an index of burn severity based on proximity of the pool to burned streamside. We estimated that salmonids of variable sizes inhabiting burned pools had to consume between 0.3-264.3 mg of additional prey over 48 days to offset the 0.01-6.04 kJ increase in metabolic demand during the first post-fire summer. However, stomach content analysis showed that fish in the burned region were consuming relatively little prey and significantly less than fish in the reference region. Presumably due to starvation, mortality, or emigration, we found a significant negative relationship between the change in total salmonid biomass over the post-fire summer and the average energy costs (kJ.g(-1).day(-1)) within a burned pool. This study demonstrates that wildfire can generate thermal heterogeneity in aquatic ecosystems and drive short-term increases in stream temperature, exacerbating bioenergetically stressful seasons for coldwater fishes. DOI
43. Beakes, MP; Moore, JW; Retford, N; Brown, R; Merz, JE; Sogard, SM. (2014) Evaluating statistical approaches to quantifying juvenile Chinook salmon habitat in a regulated California River.River Research and Applications 30: 180-191 Evaluating statistical approaches to quantifying juvenile Chinook salmon habitat in a regulated California River.
Decisions on managed flow releases in regulated rivers should be informed by the best available science. To do this, resource managers require adequate information regarding the tradeoffs between alternative methodologies. In this study, we quantitatively compare two competing multivariate habitat models for juvenile Chinook salmon (Oncorhynchus tschawytscha), a highly valued fish species under serious decline in a large extent of its range. We conducted large-scale snorkel surveys in the American River, California, to obtain a common dataset for model parameterization. We built one habitat model using Akaike Information Criterion analysis and model averaging, ‘model G’, and a second model by using a standard method of aggregating univariate habitat models, ‘model A’. We calculated Cohen’s kappa, percent correctly classified, sensitivity, specificity and the area under a receiver operator characteristic to compare the ability of each model to predict juvenile salmon presence and absence. We compared the predicted useable habitat of each model at nine simulated river discharges where usable habitat is equal to the product of a spatial area and the probability of habitat occupancy at that location. Generally, model G maintained greater predictive accuracy with a difference within 10% across the diagnostic statistics. Two key distinctions between models were that model G predicted 17.2% less useable habitat across simulated flows and had 5% fewer false positive classifications than model A. In contrast, model A had a tendency to over predict habitat occupancy and under predict model uncertainty. The largest discrepancy between model predictions occurred at the lowest flows simulated and in the habitats most likely to be occupied by juvenile salmon. This study supports the utility and quantitative framework of Akaike Information Criterion analysis and model averaging in developing habitat models. DOI
42. Beakes, MP; Sharron, S; Charish, R; Moore, JW; Satterthwaite, WH; Sturm, E; Wells, BK; Sogard, SM; Mangel, M. (2014) Using scale characteristics and water temperature to reconstruct growth rates of juvenile steelhead Oncorhynchus mykiss.Journal of Fish Biology 84: 58-72 Using scale characteristics and water temperature to reconstruct growth rates of juvenile steelhead Oncorhynchus mykiss
circuli; life history; rainbow trout; salmonids; scale analysis
Juvenile steelhead Oncorhynchus mykiss from a northern California Central Valley population were reared in a controlled laboratory experiment. Significantly different rates of growth were observed among fish reared under two ration treatments and three temperature treatments (8, 14 and 20 degrees C). Wider circulus spacing and faster deposition was associated with faster growth. For the same growth rate, however, circulus spacing was two-fold wider and deposited 36% less frequently in the cold compared to the hot temperature treatment. In a multiple linear regression, median circulus spacing and water temperature accounted for 68% of the variation in observed O. mykiss growth. These results corroborate previous research on scale characteristics and growth, while providing novel evidence that highlights the importance of water temperature in these relationships. Thus, this study establishes the utility of using scale analysis as a relatively non-invasive method for inferring growth in salmonids. (C) 2013 The Fisheries Society of the British Isles DOI
41. Favaro, C; Moore, JW; Reynolds, JD; Beakes, MP. (2014) Potential loss and rehabilitation of stream longitudinal connectivity: fish populations in urban streams with culverts.Can. J. Fish. Aquat. Sci. 71: 1805-1816 Potential loss and rehabilitation of stream longitudinal connectivity: fish populations in urban streams with culverts
Riverine connectivity is important to the persistence of fish communities, but culverts may impede fish movements to varying degrees and in both directions. Baffles can be installed in culverts to mitigate upstream connectivity loss; however, evaluation of their effectiveness is limited. To examine the potential impacts of culverts and their potential rehabilitation with baffles, we sampled fish populations in 26 streams that contained either (i) nonbaffled culverts or (ii) baffled culverts or (iii) lacked culverts (reference streams) in Metro Vancouver, British Columbia, Canada. Using mixed effects models, we compared fish responses across these three stream types to infer effects at the whole-stream scale (i.e., over both upstream and downstream positions equally), the within-stream scale (i.e., upstream versus downstream of culverts), and the interaction of scales. Densities (n.m(-2)) of coastrange sculpin (Cottus aleuticus) and prickly sculpin (Cottus asper) were significantly lower in nonbaffled and baffled stream types than in reference stream types, while densities of cutthroat trout (Oncorhynchus clarkii) and rainbow trout (Oncorhynchus mykiss) were significantly lower in reference stream types, indicating whole-stream differences. Using multivariate statistics, we similarly found that fish community compositions were significantly different across stream types. For our various fish responses, we found no interaction between stream type and upstream or downstream position. Further, we found reaches directly downstream of baffled culverts had greater fish biomass and that overall species richness increased with age of baffles. These data suggest that culverts may drive changes in fish populations at whole-stream scales, and restoration of these effects with baffles may take decades. DOI
40.Moore, JW; Lambert, TD; Heady, WN; Honig, SE; Osterback, AMK; Phillis, CC; Quiros, AL; Retford, NA; Herbst, DB. (2014) Anthropogenic land-use signals propagate through stream food webs in a California, USA, watershed.Limnologica 46: 124-130 Anthropogenic land-use signals propagate through stream food webs in a California, USA, watershed
Allochthonous; Bayesian statistics; Nitrogen; Non-point pollution; Septic systems; Stable isotopes; Subsidy
Human development of watersheds can change aquatic ecosystems via multiple pathways. For instance, human rural development may add nutrients to ecosystems. We used naturally occurring stable isotopes in stream food webs to investigate how land use affects stream ecosystems across a gradient of land development in the San Lorenzo watershed, California. Road density was used as a proxy for land development. We found that streams in watersheds with higher road densities had elevated concentrations of phosphate and nitrate. Furthermore, algal delta N-15 values increased as a function of nitrate concentration, but saturated at approximately 6 parts per thousand. This saturating pattern was consistent with a two-source mixing model with anthropogenic and watershed sources, fit using Bayesian model fitting. In sites that had >2.6 km roads km(-2), anthropogenic sources of N were estimated to represent >90% of the N pool. This anthropogenic N signal was propagated to stream consumers: rainbow trout (Oncorhynchus mykiss), signal crayfish (Pacifasticus leniusculus), and benthic invertebrate delta N-15 were positively correlated with algal delta N-15. Even relatively low density rural human land use may have substantial impacts on nutrient cycling of stream ecosystems. (C) 2014 Elsevier GmbH. All rights reserved. DOI
39.Moore, JW; Yeakel, JD; Peard, D; Lough, J; Beere, M. (2014) Life-history diversity and its importance to population stability and persistence of a migratory fish: steelhead in two large North American watersheds.J. Anim. Ecol. 83: 1035-1046 Life-history diversity and its importance to population stability and persistence of a migratory fish: steelhead in two large North American watersheds
biocomplexity; climate change; diversity-stability; iteroparity; marine survival; portfolio effect; rainbow trout
1. Life-history strategies can buffer individuals and populations from environmental variability. For instance, it is possible that asynchronous dynamics among different life histories can stabilize populations through portfolio effects. 2. Here, we examine life-history diversity and its importance to stability for an iconic migratory fish species. In particular, we examined steelhead (Oncorhynchus mykiss), an anadromous and iteroparous salmonid, in two large, relatively pristine, watersheds, the Skeena and Nass, in north-western British Columbia, Canada. We synthesized life-history information derived from scales collected from adult steelhead (N = 7227) in these watersheds across a decade. 3. These migratory fishes expressed 36 different manifestations of the anadromous life-history strategy, with 16 different combinations of freshwater and marine ages, 7.6% of fish performing multiple spawning migrations, and up to a maximum of four spawning migrations per lifetime. Furthermore, in the Nass watershed, various life histories were differently prevalent through time - three different life histories were the most prevalent in a given year, and no life history ever represented more than 45% of the population. 4. These asynchronous dynamics among life histories decreased the variability of numerical abundance and biomass of the aggregated population so that it was >20% more stable than the stability of the weighted average of specific life histories: evidence of a substantial portfolio effect. Year of ocean entry was a key driver of dynamics; the median correlation coefficient of abundance of life histories that entered the ocean the same year was 2.5 times higher than the median pairwise coefficient of life histories that entered the ocean at different times. Simulations illustrated how different elements of life-history diversity contribute to stability and persistence of populations. 5. This study provides evidence that life-history diversity can dampen fluctuations in population abundances and biomass via portfolio effects. Conserving genetic integrity and habitat diversity in these and other large watersheds can enable a diversity of life histories that increases population and biomass stability in the face of environmental variability. DOI PubMed
38. Phillips, DL; Inger, R; Bearhop, S; Jackson, AL; Moore, JW; Parnell, AC; Semmens, BX; Ward, EJ. (2014) Best practices for use of stable isotope mixing models in food-web studies.Canadian Journal of Zoology 92: 823-835 Best practices for use of stable isotope mixing models in food-web studies
consumers; diet; food chain; isotopic ratios; trophic level
Stable isotope mixing models are increasingly used to quantify consumer diets, but may be misused and misinterpreted. We address major challenges to their effective application. Mixing models have increased rapidly in sophistication. Current models estimate probability distributions of source contributions, have user-friendly interfaces, and incorporate complexities such as variability in isotope signatures, discrimination factors, hierarchical variance structure, covariates, and concentration dependence. For proper implementation of mixing models, we offer the following suggestions. First, mixing models can only be as good as the study and data. Studies should have clear questions, be informed by knowledge of the system, and have strong sampling designs to effectively characterize isotope variability of consumers and resources on proper spatio-temporal scales. Second, studies should use models appropriate for the question and recognize their assumptions and limitations. Decisions about source grouping or incorporation of concentration dependence can influence results. Third, studies should be careful about interpretation of model outputs. Mixing models generally estimate proportions of assimilated resources with substantial uncertainty distributions. Last, common sense, such as graphing data before analyzing, is essential to maximize usefulness of these tools. We hope these suggestions for effective implementation of stable isotope mixing models will aid continued development and application of this field. DOI
37. Yeakel, JD; Moore, JW; Guimaraes, PR; de Aguiar, MAM. (2014) Synchronisation and stability in river metapopulation networks.Ecology Letters 17: 273-283 Synchronisation and stability in river metapopulation networks
Fluctuations; metapopulations; river networks; stability; synchronisation
Spatial structure in landscapes impacts population stability. Two linked components of stability have large consequences for persistence: first, statistical stability as the lack of temporal fluctuations; second, synchronisation as an aspect of dynamic stability, which erodes metapopulation rescue effects. Here, we determine the influence of river network structure on the stability of riverine metapopulations. We introduce an approach that converts river networks to metapopulation networks, and analytically show how fluctuation magnitude is influenced by interaction structure. We show that river metapopulation complexity (in terms of branching prevalence) has nonlinear dampening effects on population fluctuations, and can also buffer against synchronisation. We conclude by showing that river transects generally increase synchronisation, while the spatial scale of interaction has nonlinear effects on synchronised dynamics. Our results indicate that this dual stability - conferred by fluctuation and synchronisation dampening - emerges from interaction structure in rivers, and this may strongly influence the persistence of river metapopulations. DOI
36. Frechette, D., A.L. Collins, J.T. Harvey, S.A. Hayes, D.D. Huff, A.W. Jones, N.A. Retford, A.E. Langford, J.M. Moore, A.-M. Osterback, W.H. Satterthwaite, and S.A. Shaffer. (2013) A Bioenergetics Approach to Assessing Potential Impacts of Avian Predation on Juvenile Steelhead during Freshwater Rearing.North American Journal of Fisheries Management 33:1024-1038 A Bioenergetics Approach to Assessing Potential Impacts of Avian Predation on Juvenile Steelhead during Freshwater Rearing.
Avian predation on juvenile salmonids is an important source of mortality in freshwater and estuarine habitats when birds and salmonids overlap spatially and temporally.We assessed the potential impact of avian predation upon juvenile steelhead Oncorhynchus mykiss in a coastal watershed in central California. We conducted stream surveys between 2008 and 2010 to determine the composition, distribution, and density of piscivorous birds in areas that provide rearing habitat for juvenile steelhead. The most commonly sighted bird species were common mergansers Mergus merganser and belted kingfishers Megacyrle alcyon. The density of avian predators varied spatially and temporally but was greatest in the estuary regardless of season and decreased with increasing distance from the estuary. In the absence of local predator diet data, we applied a bioenergetics model to estimate the potential predation on juvenile steelhead by mergansers and kingfishers in the Scott Creek estuary. Model parameters included (1) published values of bird energetic requirements and steelhead energy density, (2) the number of birds present in the estuary during the closure period (from stream surveys), and (3) the size frequency and abundance of steelhead present in the estuary during closure. We predicted the extent of predation for different values of steelhead in bird diets, accounting for uncertainty in the estimates using aMonte Carlo simulation approach.With the assumed contribution of steelhead to the diet ranging from 20% to 100%, the population of kingfishers foraging in the Scott Creek estuary had the potential to remove 3-17% of annual production, whereas mergansers had the potential to remove 5-54% of annual steelhead production. Our results suggest that predation by avian species, particularly mergansers, is an important source of mortality for threatened steelhead populations in central California and should be addressed in future salmonid research and recovery planning.Website DOI
35.Moore, K.D., and J.W. Moore. (2013) Ecological restoration and enabling behavior: a new metaphoric lens?Conservation Letters 6:1-5 Ecological restoration and enabling behavior: a new metaphoric lens?
Ecological restoration practices are changing rapidly, dramatically, and in complex ways, with higher and higher stakes both for the restoration industries themselves and for the future of biodiversity and ecosystem services. Even as ecosystem degradation has accelerated, restoration has grown into a transnational, multibillion dollar industry. These changes create an imperative for correspondingly rapid and dramatic changes in the metaphoric lenses through which we view restoration projects. In this Policy Perspectives paper, we explore a metaphor that views ecological restoration through the lens of codependency theories about enabling behaviors in the lives of addicts. The metaphor raises questions about the nature of the relation between restoration practices and an industrial growth economy “addicted” to cheap fuel and consumer goods. It suggests some policy changes that might prevent development of co-dependencies between restoration industries and ecologically destructive practices.PDF DOI
34. Osterback, A.-M., D.M. Frechette, A.O. Shelton, S.A. Hayes, M.H. Bond, S.A. Shaffer, and J.M. Moore. (2013) High predation on small populations: avian predation on imperiled salmonids.Ecosphere 4:116 High predation on small populations: avian predation on imperiled salmonids.
Generalist predators can contribute to extinction risk of imperiled prey populations even through incidental predation. Quantifying predation on small populations is important to manage their recovery, however predation is often challenging to observe directly. Recovery of prey tags at predator colonies can indirectly provide minimum estimates of predation, however overall predation rates often remain unquantifiable because an unknown proportion of tags are deposited off-colony. Here, we estimated overall predation rates on threatened wild juvenile steelhead (Oncorhynchus mykiss) by generalist adult Western Gulls (Larus occidentalis) in six central California (USA) watersheds. We estimated predation rates by gulls from the recapture of PIT (passive integrated transponder) tags that were originally inserted into steelhead and were subsequently deposited at a Western Gull breeding colony, Año Nuevo Island (ANI). We combined three independent datasets to isolate different processes: (1) the probability a tagged steelhead was consumed during predation, (2) the probability a consumed tag was transported to ANI, and (3) the probability a transported tag was detected at ANI. Together, these datasets parameterized a hierarchical Bayesian model to quantify overall predation rates while accounting for tag loss between when prey were tagged and subsequent tag detection at ANI. Results from the model suggest that low recovery rates of PIT tags from steelhead at ANI were mostly driven by low probabilities of transportation (≤0.167) of consumed tags to ANI. Low transportation probabilities equate to high per-capita probabilities of predation (≥0.306/yr) at the three watersheds in closest proximity to ANI, whereas predation rates were uncertain at watersheds farther from ANI due to very low transportation rates. This study provides the first overall estimate of Western Gull predation rates on threatened wild juvenile steelhead and suggests gull predation on salmonids is a larger source of mortality than was previously estimated from minimum predation rates. This study thus represents an important example of high rates of incidental predation by a generalist consumer on an imperiled prey and provides a quantitative framework to inform robust estimates of predation rates on small populations that can be applied to other systems where direct observation of predation is not feasible.Website
33. Scott, D., J.W. Moore, L.-M. Herborg, C.C. Murray, and N.R. Serrao. (2013) Capture, genetics, isotopes, and policy consequences of a non-native snakehead in Canada.Management of Biological Invasions. In Press Capture, genetics, isotopes, and policy consequences of a non-native snakehead in Canada.
In June 2012 a single non-native snakehead fish was captured by local officials in a small pond within an urban park in Burnaby, British Columbia. This single snakehead fish garnered significant attention in the local and national media. DNA analysis determined it to be a blotched snakehead (Channa maculata) or possibly a hybrid; a warm water species native to China and Vietnam which is commonly sold in the live food fish trade, and occasionally kept by lobbyists. By collecting prey items from the pond and snakehead specimens from fish markets we used a novel stable isotope approach to estimate how long it had been since the snakehead had been released into the pond. Using a diet-switching tissue turnover model, we estimated that the snakehead was in the pond between 33 and 93 days. Subsequently, provincial legislation was amended to ban all species of snakehead fish, as well as numerous other potentially invasive fish and invertebrate species.PDF
32. Semmens, B.X., E.J. Ward, A.C. Parnell, D.L. Phillips, S. Bearhop, R. Inger, A. Jackson, and J.M. Moore. (2013) Statistical basis and outputs of stable isotope mixing models: Comment on Fry (2013).Marine Ecology Progress Series 490: 285-289. Statistical basis and outputs of stable isotope mixing models: Comment on Fry (2013).
Fry (2013; Mar Ecol Prog Ser 472:1-13) reviewed approaches to solving underdetermined stable isotope mixing systems, and presented a novel approach based on graphical summaries. He inaccurately characterized the statistics and interpretation of outputs from IsoSource and more recent Bayesian mixing model tools (e.g. SIAR, MixSIR), however, and as an alternative promoted an approach—not based on likelihood methods—that uses graphing and 2 new metrics for tracking source contributions to a mixture. Fry’s approach does not provide statistical probability densities associated with source contribution parameter estimates, has little applicability to complex mixing systems such as hierarchical models, and relies on the subjective interpretation of graphing products. We clarify the analytic theory underlying common mixing model approaches and provide an analysis of the 4-source, 2-tracer underdetermined mixing system example in Fry (2013), using both a Bayesian mixing model and Fry’s graphical analysis and summary metrics. We demonstrate that properly interpreted Bayesian approaches yield distributions of parameter estimates that can reflect multi-modality, covariance and parameter uncertainty.Website
31. Semmens, BX; Ward, EJ; Parnell, AC; Phillips, DL; Bearhop, S; Inger, R; Jackson, A; Moore, JW. (2013) Statistical basis and outputs of stable isotope mixing models: Comment on Fry (2013).Mar. Ecol.-Prog. Ser. 490: 285-289 Statistical basis and outputs of stable isotope mixing models: Comment on Fry (2013)
Bayesian mixing model; SIAR; MixSIR; IsoSource
Fry (2013; Mar Ecol Prog Ser 472:1-13) reviewed approaches to solving underdetermined stable isotope mixing systems, and presented a novel approach based on graphical summaries. He inaccurately characterized the statistics and interpretation of outputs from IsoSource and more recent Bayesian mixing model tools (e. g. SIAR, MixSIR), however, and as an alternative promoted an approach-not based on likelihood methods-that uses graphing and 2 new metrics for tracking source contributions to a mixture. Fry's approach does not provide statistical probability densities associated with source contribution parameter estimates, has little applicability to complex mixing systems such as hierarchical models, and relies on the subjective interpretation of graphing products. We clarify the analytic theory underlying common mixing model approaches and provide an analysis of the 4-source, 2-tracer underdetermined mixing system example in Fry (2013), using both a Bayesian mixing model and Fry's graphical analysis and summary metrics. We demonstrate that properly interpreted Bayesian approaches yield distributions of parameter estimates that can reflect multi-modality, covariance and parameter uncertainty. DOI
30. Yeakel, J.D., J.W. Moore, M. de Aguiar, and P. Guimarães. (2013) Stability and synchronization in river networks.Ecology Letters In Press Stability and synchronization in river networks.
Spatial structure in landscapes impacts population stability. Two linked components of stability have large consequences for persistence: first, statistical stability as the lack of temporal fluctuations; second, synchronisation as an aspect of dynamic stability, which erodes metapopulation rescue effects. Here, we determine the influence of river network structure on the stability of riverine metapopulations. We introduce an approach that converts river networks to metapopulation networks, and analytically show how fluctuation magnitude is influenced by interaction structure. We show that river metapopulation complexity (in terms of branching prevalence) has nonlinear dampening effects on population fluctuations, and can also buffer against synchronisation. We conclude by showing that river transects generally increase synchronisation, while the spatial scale of interaction has nonlinear effects on synchronised dynamics. Our results indicate that this dual stability - conferred by fluctuation and synchronisation dampening - emerges from interaction structure in rivers, and this may strongly influence the persistence of river metapopulations.PDF
29. Frechette, D; Osterback, AMK; Hayes, SA; Bond, MH; Moore, JW; Shaffer, SA; Harvey, JT. (2012) Assessing Avian Predation on Juvenile Salmonids using Passive Integrated Transponder Tag Recoveries and Mark-Recapture Methods.North Am. J. Fish Manage. 32: 1237-1250 Assessing Avian Predation on Juvenile Salmonids using Passive Integrated Transponder Tag Recoveries and Mark-Recapture Methods
Many populations of coho salmon Oncorhynchus kisutch and steelhead O. mykiss are listed under the U.S. Endangered Species Act. Until recently, the role of avian predation in limiting recovery of coho salmon and steelhead in central California coastal watersheds has been overlooked. We used recoveries of passive integrated transponder (PIT) tags from Ano Nuevo Island (ANI), a breeding site for several species of piscivorous seabirds, to estimate predation rates on juvenile salmonids and identify susceptible life stages and species responsible for predation. A total of 34,485 PIT tags were deployed in coho salmon and steelhead in six watersheds in San Mateo and Santa Cruz counties. Tags were deposited on ANI by predators after ingestion of tagged fish. Because tags were not removed from the island and were detected on multiple sampling occasions, we were able to use markrecapture models to generate a corrected minimum predation estimate. We used POPAN, a variation of the JollySeber model, to generate an estimate of gross population abundance, which accounted for tags deposited on the island but not detected during surveys. Detections of 196 tags from surveys conducted between autumn 2006 and spring 2009 were incorporated into the model, producing a gross population estimate of 242 tags (SE = 9.8). Addition of tags detected between autumn 2009 and 2010 to the abundance estimate from POPAN produced a new minimum estimate of 362 tags on ANI. Western gulls Larus occidentalis probably were the primary predator depositing tags on ANI. Minimum predation estimates ranged from 0.1% (Soquel Creek) to 4.6% (Waddell Creek) of outmigrating coho salmon and steelhead smolts. Predation was potentially greater given still unquantified deposition of tags off-colony and destruction of tags during digestive processes of predators. Finally, avian predators targeted estuary-reared fish, which contributed disproportionately to adult populations, further impacting imperiled salmon populations. Received August 4, 2011; accepted August 27, 2012 DOI
28.Moore, J.W., D.B. Herbst, W.N. Heady, and S.M. Carlson. (2012) Stream community and ecosystem responses to the boom and bust of an invading snail.Biological Invasions 14: 2435-2446 Stream community and ecosystem responses to the boom and bust of an invading snail.
Invasive species can fundamentally change ecosystems, but there remains surprisingly little understanding of how they alter ecosystems through time. New Zealand mudsnails (NZMS, Potamopyrgus antipodarum) are invading North American aquatic ecosystems with potentially enormous impacts on stream communities and ecosystems. Here we present a unique 10 year time series of stream benthic invertebrates in two sites in a California stream—one invaded site where NZMS populations boomed and then busted, and one upstream reference site that was not invaded to the same degree. As NZMS populations rose and fell, the abundance of native grazing herbivores crashed and then recovered, evidence of direct negative competitive impacts of NZMS. However, NZMS had a positive indirect effect on piercing herbivores, probably mediated by a shift in the dominant algal type. Retrospective stable isotope analyses and Bayesian isotopic mixing models revealed that NZMS invasion decreased the reliance of native taxa, from a variety of functional feeding groups, on periphyton-derived carbon. Furthermore, NZMS invasion was associated with depleted nitrogen stable isotope signatures, evidence that NZMS alter stream ecosystem nitrogen cycling. The reference site did not exhibit these community- or ecosystem-level dynamics. Thus, invasive herbivores can have strong top-down and bottom-up influences on invaded ecosystems, but these impacts can be extremely temporally dynamic.PDF DOI
27.Moore, JW; Carlson, SM; Twardochleb, LA; Hwan, JL; Fox, JM; Hayes, SA. (2012) Trophic Tangles through Time? Opposing Direct and Indirect Effects of an Invasive Omnivore on Stream Ecosystem Processes.PLoS One 7 Trophic Tangles through Time? Opposing Direct and Indirect Effects of an Invasive Omnivore on Stream Ecosystem Processes
Omnivores can impact ecosystems via opposing direct or indirect effects. For example, omnivores that feed on herbivores and plants could either increase plant biomass due to the removal of herbivores or decrease plant biomass due to direct consumption. Thus, empirical quantification of the relative importance of direct and indirect impacts of omnivores is needed, especially the impacts of invasive omnivores. Here we investigated how an invasive omnivore (signal crayfish, Pacifastacus leniusculus) impacts stream ecosystems. First, we performed a large-scale experiment to examine the short-term (three month) direct and indirect impacts of crayfish on a stream food web. Second, we performed a comparative study of un-invaded areas and areas invaded 90 years ago to examine whether patterns from the experiment scaled up to longer time frames. In the experiment, crayfish increased leaf litter breakdown rate, decreased the abundance and biomass of other benthic invertebrates, and increased algal production. Thus, crayfish controlled detritus via direct consumption and likely drove a trophic cascade through predation on grazers. Consistent with the experiment, the comparative study also found that benthic invertebrate biomass decreased with crayfish. However, contrary to the experiment, crayfish presence was not significantly associated with higher leaf litter breakdown in the comparative study. We posit that during invasion, generalist crayfish replace the more specialized native detritivores (caddisflies), thereby leading to little long-term change in net detrital breakdown. A feeding experiment revealed that these native detritivores and the crayfish were both effective consumers of detritus. Thus, the impacts of omnivores represent a temporally-shifting interplay between direct and indirect effects that can control basal resources. DOI PubMed
26. Twardochleb, L.A., M. Novak, and J.W. Moore. (2012) Using the functional response of a consumer to predict biotic resistance to invasive prey.Ecological Applications 22: 1162-1171 Using the functional response of a consumer to predict biotic resistance to invasive prey.
biotic resistance; crayfish; New Zealand mud snail; Pacifastacus leniusculus; Potamopyrgus antipodarum; predation; propagule pressure; San Lorenzo River, California, USA; stream; type 3 functional response
Predators sometimes provide biotic resistance against invasions by nonnative prey. Understanding and predicting the strength of biotic resistance remains a key challenge in invasion biology. A predator's functional response to nonnative prey may predict whether a predator can provide biotic resistance against nonnative prey at different prey densities. Surprisingly, functional responses have not been used to make quantitative predictions about biotic resistance. We parameterized the functional response of signal crayfish (Pacifastacus leniusculus) to invasive New Zealand mud snails (Potamopyrgus antipodarum; NZMS) and used this functional response and a simple model of NZMS population growth to predict the probability of biotic resistance at different predator and prey densities. Signal crayfish were effective predators of NZMS, consuming more than 900 NZMS per predator in a 12-h period, and Bayesian model fitting indicated their consumption rate followed a type 3 functional response to NZMS density. Based on this functional response and associated parameter uncertainty, we predict that NZMS will be able to invade new systems at low crayfish densities (<0.2 crayfish/m(2)) regardless of NZMS density. At intermediate to high crayfish densities (>0.2 crayfish/m(2)), we predict that low densities of NZMS will be able to establish in new communities; however, once NZMS reach a threshold density of similar to 2000 NZMS/m(2), predation by crayfish will drive negative NZMS population growth. Further, at very high densities, NZMS overwhelm predation by crayfish and invade. Thus, interacting thresholds of propagule pressure and predator densities define the probability of biotic resistance. Quantifying the shape and uncertainty of predator functional responses to nonnative prey may help predict the outcomes of invasions.PDF
25.Moore, J.W., S.A. Hayes, W. Duffy, S. Gallagher, C. Michel, and D. Wright. (2011) Nutrient fluxes and the recent collapse of coastal California salmon populations.Canadian Journal of Fisheries and Aquatic Sciences 68: 1161-1170 Nutrient fluxes and the recent collapse of coastal California salmon populations.
Migratory salmon move nutrients both in and out of fresh waters during the different parts of their life cycle. We used a mass-balance approach to quantify recent changes in phosphorus (P) fluxes in six coastal California, USA, watersheds that have recently experienced dramatic decreases in salmon populations. As adults, semelparous Chinook (Oncorhynchus tshawytscha) and coho (Oncorhynchus kisutch) salmon imported 8.3 and 10.4 times more P from the ocean, respectively, than they exported as smolts, while iteroparous steelhead (i.e., sea-run rainbow trout, Oncorhynchus mykiss) imported only 1.6 times more than they exported as kelts and smolts. Semelparous species whose life histories led them to import more nutrients were also the species whose populations decreased the most dramatically in California in recent years. In addition, the relationship between import and export was nonlinear, with export being proportionally more important at lower levels of import. This pattern was driven by two density-dependent processes - smolts were larger and disproportionately more abundant at lower spawner abundances. In fact, in four of our six streams we found evidence that salmon can drive net export of P at low abundance, evidence for the reversal of the "conveyor belt" of nutrients.Website DOI
24. Ward, E.J., B.X. Semmens, D.L. Phillips, J.W. Moore, and N. Bouwees. (2011) A quantitative approach to combine sources in stable isotope mixing models.Ecosphere 2:art19 A quantitative approach to combine sources in stable isotope mixing models.
Stable isotope mixing models, used to estimate source contributions to a mixture, typically yield highly uncertain estimates when there are many sources and relatively few isotope elements. Previously, ecologists have either accepted the uncertain contribution estimates for individual sources or addressed the problem in an ad hoc way by combining either related sources prior to analysis or the estimated proportions of related sources following analysis. Neither of these latter approaches explicitly account for uncertainty in source combinations within the likelihood framework. In this paper we incorporate uncertainty in both the number of source groups and group assignment within a formal Bayesian mixing model framework. By dynamically exploring model complexity due to aggregating sources based on shared proportional contributions, we can estimate posterior probabilities of alternative group configurations, and construct posterior dendrograms of group membership. We apply this method to simulated data, and illustrate applications to two consumer datasets (rainbow trout, coastal mink). Our results demonstrate that estimating, rather than fixing, the number of proportional contributions in a mixing model can improve model inference and reduce bias in estimates of source contributions to a mixture.Website DOI
23. Yeakel, J.D., M. Novak, P. Guimaraes, N. Dominy, P. Koch, E. Ward, J.W. Moore, and B.X. Semmens. (2011) Merging Resource Availability with Isotope Mixing Models: The Role of Neutral Interaction Assumptions.PLOS One 6:e22015 Merging Resource Availability with Isotope Mixing Models: The Role of Neutral Interaction Assumptions
Background: Bayesian mixing models have allowed for the inclusion of uncertainty and prior information in the analysis of trophic interactions using stable isotopes. Formulating prior distributions is relatively straightforward when incorporating dietary data. However, the use of data that are related, but not directly proportional, to diet (such as prey availability data) is often problematic because such information is not necessarily predictive of diet, and the information required to build a reliable prior distribution for all prey species is often unavailable. Omitting prey availability data impacts the estimation of a predator's diet and introduces the strong assumption of consumer ultrageneralism (where all prey are consumed in equal proportions), particularly when multiple prey have similar isotope values. Methodology: We develop a procedure to incorporate prey availability data into Bayesian mixing models conditional on the similarity of isotope values between two prey. If a pair of prey have similar isotope values (resulting in highly uncertain mixing model results), our model increases the weight of availability data in estimating the contribution of prey to a predator's diet. We test the utility of this method in an intertidal community against independently measured feeding rates. Conclusions: Our results indicate that our weighting procedure increases the accuracy by which consumer diets can be inferred in situations where multiple prey have similar isotope values. This suggests that the exchange of formalism for predictive power is merited, particularly when the relationship between prey availability and a predator's diet cannot be assumed for all species in a system.Website DOI
21.Moore, J.W., and D.E. Schindler. (2010) Spawning salmon and the phenology of emergence in stream insects.Proceedings of the Royal Society B-Biological Sciences 277: 1695-1703 Spawning salmon and the phenology of emergence in stream insects
ecosystem engineer; disturbance regime; bioturbation; marine-derived nutrients
Phenological dynamics are controlled by environmental factors, disturbance regimes and species interactions that alter growth or mortality risk. Ecosystem engineers can be a key source of disturbance, yet their effects on the phenologies of co-occurring organisms are virtually unexplored. We investigated how the abundance of a dominant ecosystem engineer, spawning sockeye salmon (Oncorhynchus nerka), alters the emergence phenology of stream insects. In streams with high densities of salmon, peak insect emergence occurred in early July, immediately prior to salmon spawning. By contrast, peak insect emergence in streams with low densities of salmon was weeks later and more protracted. The emergence of specific taxa was also significantly related to salmon density. A common rearing experiment revealed that differences in emergence timing are maintained in the absence of spawning salmon. We hypothesize that these patterns are probably driven by predictable and severe disturbance from nest-digging salmon driving local adaptation and being a trait filter of insect emergence. Thus, salmon regulate the timing and duration of aquatic insect emergence, a cross-ecosystem flux from streams to riparian systems. DOI
20.Moore, J.W., M. McClure, L.A. Rogers, and D.E. Schindler. (2010) Synchronization and portfolio performance of threatened salmon.Conservation Letters 3: 340-348 Synchronization and portfolio performance of threatened salmon
Biocomplexity; Chinook; coherence; portfolio effect; response diversity
Interpopulation variation in dynamics can buffer species against environmental change. We compared population synchrony in a group of threatened Chinook salmon in the highly impacted Snake River basin (Oregon, Washington, Idaho) to that in the sockeye salmon stock complex of less impact Bristol Bay (Alaska). Over the last 40 years, > 90% of populations in the Snake River basin became more synchronized with one another. However, over that period, sockeye populations from Alaska did not exhibit systemic changes in synchrony. Coincident with increasing Snake River population synchrony, there was an increase in hatchery propagation and the number of large dams, potentially homogenizing habitats and populations. A simulation using economic portfolio theory revealed that synchronization of Snake River salmon decreased risk-adjusted portfolio performance (the ratio of portfolio productivity to variance) and decreased benefits of population richness. Improving portfolio performance for exploited species, especially given future environmental change, requires protecting a diverse range of populations and the varied habitats upon which they depend.Website DOI
18. Yeakel, J.D., B.D. Patterson, K. Fox-Dobbs, M.M. Okumura, T.E. Cerline, J.W. Moore, P.L. Koch, and N.J. Dominy. (2009) Cooperation and individuality among man-eating lions.Proceedings of the National Academy of Sciences of the United States of America 106: 19040-19043 Cooperation and individuality among man-eating lions
individual dietary specialization; Panthera leo; Taita; Tsavo
Cooperation is the cornerstone of lion social behavior. In a notorious case, a coalition of two adult male lions from Tsavo, southern Kenya, cooperatively killed dozens of railway workers in 1898. The "man-eaters of Tsavo'' have since become the subject of numerous popular accounts, including three Hollywood films. Yet the full extent of the lions' man-eating behavior is unknown; estimates range widely from 28 to 135 victims. Here we use stable isotope ratios to quantify increasing dietary specialization on novel prey during a time of food limitation. For one lion, the delta(13)C and delta(15)N values of bone collagen and hair keratin (which reflect dietary inputs over years and months, respectively) reveal isotopic changes that are consistent with a progressive dietary specialization on humans. These findings not only support the hypothesis that prey scarcity drives individual dietary specialization, but also demonstrate that sustained dietary individuality can exist within a cooperative framework. The intensity of human predation (up to 30% reliance during the final months of 1898) is also associated with severe craniodental infirmities, which may have further promoted the inclusion of unconventional prey under perturbed environmental conditions. DOI
17. Zavaleta, E., J. Pasari, J.W. Moore, D. Hernández, K.B. Suttle, and C.C. Wilmers. (2009) Ecosystems responses to community disassembly.This Year in Ecology and Conservation Biology 1162: 311-333 Ecosystems responses to community disassembly.
Ecosystems around the world are experiencing unprecedented rates of extinction and species decline. The question of how community disassembly—the ongoing process of nonrandom species losses and declines—affects ecosystem functions, including those that influence persistence of other species, is addressed. The order in which species disappear from a community depends on their vulnerability to specific stressors and on traits associated with inherent susceptibility to decline. Information on species characteristics associated with vulnerability (response traits) is synthesized, and it is asked whether they are associated with characteristics that underpin significant contributions to ecosystem functioning (effect traits). Direct evidence that community disassembly affects ecosystem functioning comes from a variety of sources, ranging from documentation of long-term changes following the loss of an initial species or fragmentation of a landscape, to modeling and manipulative experiments that simulate species losses and observe their consequences. The usefulness to conservation and restoration practice of community disassembly as a concept is evaluated, and it is asked whether and how community disassembly can provide guidance about species loss order, its consequences, what each of these depends on, and whether a positive link exists between vulnerability and contribution to function—a link that would exacerbate the consequences of the ongoing extinction crisis. DOI
16.Moore, J.W., and B.X. Semmens. (2008) Incorporating uncertainty and prior information into stable isotope mixing models.Ecology Letters 11: 470-480 Incorporating uncertainty and prior information into stable isotope mixing models
bayesian; carbon; diet; food web; isotopic fractionation; MixSIR; nitrogen; rainbow trout; salmon; sampling importance resampling
Stable isotopes are a powerful tool for ecologists, often used to assess contributions of different sources to a mixture (e.g. prey to a consumer). Mixing models use stable isotope data to estimate the contribution of sources to a mixture. Uncertainty associated with mixing models is often substantial, but has not yet been fully incorporated in models. We developed a Bayesian-mixing model that estimates probability distributions of source contributions to a mixture while explicitly accounting for uncertainty associated with multiple sources, fractionation and isotope signatures. This model also allows for optional incorporation of informative prior information in analyses. We demonstrate our model using a predator-prey case study. Accounting for uncertainty in mixing model inputs can change the variability, magnitude and rank order of estimates of prey (source) contributions to the predator (mixture). Isotope mixing models need to fully account for uncertainty in order to accurately estimate source contributions. DOI
15.Moore, J.W., and D.E. Schindler. (2008) Biotic disturbance and benthic community dynamics in salmon-bearing streams.Journal of Animal Ecology 77: 275-284 Biotic disturbance and benthic community dynamics in salmon-bearing streams
bioturbation; ecosystem engineer; marine-derived nutrients; Oncorhynchus nerka; succession
1. Organisms can impact ecosystems via multiple pathways, often with positive and negative impacts on inhabitants. Understanding the context dependency of these types of impacts remains challenging. For example, organisms may perform different functions at different densities.
2. Anadromous salmon accumulate > 99% of their lifetime growth in marine ecosystems, and then return to spawn, often at high densities, in relatively confined freshwaters. While previous research has focused on how salmon nutrients can fertilize benthic communities, we examined how an ecosystem engineer, sockeye salmon Oncorhynchus nerka, influences seasonal dynamics of stream benthic communities through their nest-digging activities in south-western Alaska, USA. Benthic invertebrate and algal abundance were quantified every 7-14 days during the open water seasons of 10 streams in riffle and run habitats across multiple years, leading to 25 different stream-year combinations that spanned a large gradient of salmon density.
3. In streams with few or no salmon, benthic algal and insect biomass were fairly constant throughout the season. However, in streams with more than 0.1 salmon m(-2), algal and insect biomass decreased by an average of 75-85% during salmon spawning. Algal biomass recovered quickly following salmon disturbance, occasionally reaching pre-salmon biomass. In contrast, in streams with more than 0.1 salmon m(-2), aquatic insect populations did not recover to pre-salmon levels within the same season. We observed no positive impacts of salmon on algae or insects via fertilization from carcass nutrients.
4. Salmon, when their populations exceed thresholds in spawning density, are an important component of stream disturbance regimes and influence seasonal dynamics of benthic communities. Human activities that drive salmon densities below threshold densities, as has likely happened in many streams, will lead to altered seasonal dynamics of stream communities. Human activities that alter animal populations that are sources of biogenic disturbance can result in shifts in community dynamics. DOI
14.Moore, J.W., D.E. Schindler, and C.P. Ruff. (2008) Habitat saturation drives thresholds in stream subsidies.Ecology 89: 306-312 Habitat saturation drives thresholds in stream subsidies
density dependence; ecosystem-based management; eggs; fisheries; food web; foraging; functional extinction; grayling; marine-derived nutrients; salmon; superimposition; trout
Understanding how abundance regulates the effects of organisms on their ecosystems remains a critical goal of ecology, especially for understanding inter-ecosystem transfers of energy and nutrients. Here we examined how territoriality and nest-digging by anadromous salmon mediate trophic subsidies to stream fishes. Salmon eggs become available for consumption primarily by the digging of salmon that superimpose their nests on previous nests. An individual-based model of spawning salmon predicted that territoriality and habitat saturation produce a nonlinear effect of salmon density on numbers of available eggs to resident predators. Field studies in Alaskan streams found that higher densities of salmon produce disproportionately more eggs in stream drift and in diets of resident fishes ( Arctic grayling and rainbow trout). Bioenergetics model simulations indicated that these subsidies produce substantially enhanced growth rates of trout. These results demonstrate that small changes in salmon abundance can drive large changes in subsidies to stream food webs. Thus, the ecological consequences of population declines of keystone species, such as salmon, will be exacerbated when behavior generates nonlinear impacts. DOI
13.Moore, J.W., D.E. Schindler, J.L. Carter, J.M. Fox, J. Griffiths, and G.W. Holtgrieve. (2007) Biotic control of stream fluxes: Spawning salmon drive nutrient and matter export.Ecology 88: 1278-1291 Biotic control of stream fluxes: Spawning salmon drive nutrient and matter export
Alaska; USA; bioturbation; disturbance; ecosystem engineer; excretion; marine-derived nutrients; mass balance; Oncorhynchus nerka; redd; sockeye salmon; subsidy
Organisms can control movements of nutrients and matter by physically modifying habitat. We examined how an ecosystem engineer, sockeye salmon (Oncorhynchus nerka), influences seasonal fluxes of sediments, nitrogen (N), and phosphorus (P) in streams of southwestern Alaska. The purpose of this study was to investigate whether salmon act as net importers or net exporters of matter and nutrients from streams and how these roles change as a function of salmon population density. We measured discharge and concentrations of suspended sediments and total N and P every 7-14 days for up to four summers in 10 streams spanning a gradient in salmon densities. We statistically allocated whole-season fluxes to salmon activities, such as excretion and bioturbation, and to export by hydrologic discharge. In addition, we used counts of spawning salmon to estimate nutrient and matter imports by salmon to streams. Large seasonal pulses of suspended sediments, P, and N were associated with salmon spawning activities, often increasing export an order of magnitude higher than during pre-salmon levels. Years and streams with more salmon had significantly higher levels of export of sediments and nutrients. In addition, years with higher precipitation had higher background export of P and N. Salmon exported an average of the equivalent of 189%, 60%, and 55% of total matter, P, and N that salmon imported in their bodies. The relative magnitude of export varied; salmon exported more than their bodies imported in 80%, 20%, and 16% across all streams and years for sediments, P, and N, respectively. A bioassay experiment indicated that the P exported by salmon is directly available for use by primary producers in the downstream lake. These results demonstrate that salmon not only move nutrients upstream on large spatial scales via their migration from the ocean and subsequent death, but also redistribute matter and nutrients on finer spatial scales through their spawning activities. DOI
11. Brock, CS; Leavitt, PR; Schindler, DE; Johnson, SP; Moore, JW. (2006) Spatial variability of stable isotopes and fossil pigments in surface sediments of Alaskan coastal lakes: Constraints on quantitative estimates of past salmon abundance.Limnology and Oceanography 51: 1637-1647 Spatial variability of stable isotopes and fossil pigments in surface sediments of Alaskan coastal lakes: Constraints on quantitative estimates of past salmon abundance
We quantified spatial patterns of stable isotopes of N and C (delta N-15, delta C-13) and fossil pigment concentrations in the uppermost 10 mm of sediment (similar to 10 yr) from 74 profundal locations and three spawning-stream discharge areas in Lake Nerka, southwest Alaska. Sediment delta N-15 (4.3 parts per thousand +/- 0.7 parts per thousand) and delta C-13 (-26.3 parts per thousand +/- 1.2 parts per thousand) varied directly (delta N-15) or inversely (delta C-13) with water column depth, whereas concentrations of most fossil pigments from algae were negatively correlated with depth. Sediment delta N-15 and delta C-13 were poorly correlated with either fossil pigment abundance or the local densities of spawning salmon. Instead, coastal nursery lakes appeared to integrate marine-derived nutrients rapidly into lakewide nutrient pools, suggesting that while individual cores may be used to reconstruct whole-lake salmon densities, habitat-specific variations of past fish populations cannot be quantified reliably from sedimentary analyses.PDF
8. Payne, LX; Moore, JW. (2006) Mobile scavengers create hotspots of freshwater productivity.Oikos 115: 69-80 Mobile scavengers create hotspots of freshwater productivity
Adjacent communities and ecosystems often differ in underlying productivity but are connected by flows of nutrients, energy, and matter. Pacific salmon (Oncorhynchus spp.) transport substantial quantities of nutrients from marine ecosystems to coastal freshwater habitats when they return to spawn and die. Nutrients from their carcasses are initially concentrated in spawning streams and lakes, but are subsequently dispersed by abiotic (floods, hyporheic flow) and biotic processes (predators and scavengers). In southwest Alaska, mobile avian scavengers (gulls; Larus spp.) breed on small islands within salmon nursery lakes and consume large quantities of spawning salmon during the chick-rearing period. However the role of birds as vectors of salmon-derived nutrients remains unknown. We examined how gulls - by transporting salmon tissues to their chicks - create hotspots of biological productivity in the aquatic habitats surrounding their nesting colonies. We found that algal production was similar to 10x higher at islands with high gull densities compared to islands without nesting gulls, but was concentrated within 40 m of island shorelines. Carbon stable isotopes (delta C-13) confirmed that gulls enhance primary production in local benthic communities and demonstrated that this production was transferred up the food web to grazers (snails) and carnivores (blackfish). Nitrogen stable isotopes (delta N-15) confirmed that salmon dominated the diet of gulls and that nutrients from gull guano were incorporated into algae and passed up the food web. By relocating and concentrating salmon-derived nutrients into new and distant locations, gulls alter and magnify production in local aquatic communities. We offer the first evidence that the avian community can move salmon-derived nutrients great distances, enriching otherwise isolated habitats.PDF
7. Winder, M; Schindler, DE; Moore, JW; Johnson, SP; Palen, WJ. (2005) Do bears facilitate transfer of salmon resources to aquatic macroinvertebrates?Canadian Journal of Fisheries and Aquatic Sciences 62: 2285-2293 Do bears facilitate transfer of salmon resources to aquatic macroinvertebrates?
In coastal areas of the Pacific Northwest bears (Ursus spp.) prey heavily on spawning Pacific salmon (Oncorhynchus spp.) and selectively kill energy-rich individuals that are the most recent arrivals on spawning grounds. Pacific salmon eventually die in spawning habitats anyway, albeit with considerably lower energetic content. We investigated whether foraging activities of bears facilitate growth of stream invertebrates by increasing the duration of salmon carcass availability and the nutritional value of carcasses for scavengers. Our survey in southwest Alaska showed that carcasses are highly colonized by caddisfly (Trichoptera) larvae. Caddisflies show a strong preference for bear-killed over senescent carcasses, which may be a result of extended temporal availability, improved accessibility of consumable tissue, and higher energetic content of bear-killed fish. Isotope analyses further indicate uptake of marine-derived nutrients in caddisflies during the salmon run, which, however, does not extend into subsequent generations. Thus, species with life histories linked to the annual marine derived nutrient pulse gain the biggest advantage from the salmon resource subsidy. A long-term survey in several creeks in this region showed that bear predation intensity varied greatly among creeks and years, therefore indirect effects of bear predation on aquatic scavengers are likely highly patchy in time and space. DOI
5.Moore, JW; Kenagy, GJ. (2004) Consumption of shrews, Sorex spp., by Arctic Grayling, Thymallus arcticus.Canadian Field-Naturalist 118: 111-114 Consumption of shrews, Sorex spp., by Arctic Grayling, Thymallus arcticus
Arctic Grayling; Thymallus arcticus; diet; salmon-derived nutrients; shrews; Sorex spp.; stable isotopes
In an investigation of the dietary habits of Arctic Grayling (Thymallus arcticus) we found that two individuals out of 93 sampled in southwestern Alaska (approximately 59degreesN, 159degreesW) contained a total of five shrews (Sorex spp.). These shrews contained enriched levels of nitrogen stable isotopes, suggesting utilization of nutrients derived from salmon. We hypothesize that normally terrestrial shrews accidentally enter streams while foraging along the productive riparian zones of creeks with high densities of salmon. Shrews are apparently susceptible to opportunistic predation by resident stream fishes, including Arctic Grayling, when they enter the streams.
4.Moore, JW; Ruesink, JL; McDonald, KA. (2004) Impact of supply-side ecology on consumer-mediated coexistence: Evidence from a meta-analysis.American Naturalist 163: 480-487 Impact of supply-side ecology on consumer-mediated coexistence: Evidence from a meta-analysis
diversity; marine; meta-analysis; recruitment; rocky intertidal; succession
Studies of marine nearshore hard substrates have demonstrated that consumers and abiotic disturbances can remove biomass, clearing space for species that are competitively subordinate and subsequently increasing diversity. However, studies often examine the impact of these space-opening forces on diversity in isolation from other potentially interacting factors. In marine systems, space can be closed by recruitment decoupled from local populations. Therefore, we investigated how recruitment influences the impacts of consumers on diversity with a meta-analysis of 27 experiments of community development involving sessile species on marine hard substrates. These studies allowed quantification of recruitment rates, consumer pressure, and species richness of primary space occupants. This meta-analysis demonstrated that consumers generally increase diversity at high levels of recruitment but decrease diversity at low levels of recruitment. Therefore, species diversity of sessile species is controlled by the interaction between forces that open (predation and herbivory) and close (recruitment) space. DOI
3.Moore, JW; Schindler, DE; Scheuerell, MD. (2004) Disturbance of freshwater habitats by anadromous salmon in Alaska.Oecologia 139: 298-308 Disturbance of freshwater habitats by anadromous salmon in Alaska
benthic invertebrates; bioturbation.; ecosystem engineer; habitat modification; Oncorhynchus
High densities of habitat modifiers can dramatically alter the structure of ecosystems. Whereas spawning sockeye salmon (Oncorhynchus nerka) dig nests that cover over 2 m(2) and are at least 20 cm deep, and can spawn at high densities, relatively little attention has been devoted to investigating the impacts of this disturbance. We hypothesized that this temporally and spatially predictable bioturbation has large impacts on the coastal aquatic habitats used by sockeye. We experimentally investigated the impacts of disturbance caused by spawning sockeye in two streams and two lakes in Alaska by excluding salmon from 2.25 m(2) plots where they traditionally spawn. We sampled exclusions and control plots before, during, and after spawning. During sockeye spawning, fine sediment accumulated in areas where sockeye were excluded from spawning. In addition, sockeye spawning significantly decreased algal biomass by 80% compared to exclusion plots. We found mixed effects of spawning on the invertebrate assemblage. Tricladida and Chironomidae densities increased by 3x in exclusion plots relative to control plots in one creek site. However, for most taxa and sites, invertebrate densities declined substantially as spawning progressed, regardless of experimental treatment. Habitat modification by spawning salmon alters both community organization and ecosystem processes. DOI
1. Schindler, DE; Scheuerell, MD; Moore, JW; Gende, SM; Francis, TB; Palen, WJ. (2003) Pacific salmon and the ecology of coastal ecosystems.Frontiers in Ecology and the Environment 1: 31-37 Pacific salmon and the ecology of coastal ecosystems
One of the most spectacular phenomena in nature is the annual return of millions of salmon to spawn in their natal streams and lakes along the Pacific coast of North America. The salmon die after spawning, and the nutrients and energy in their bodies, derived almost entirely from marine sources, are deposited in the freshwater ecosystems. This represents a vital input to the ecosystems used as spawning grounds. Salmon-derived nutrients make up a substantial fraction of the plants and animals in aquatic and terrestrial habitats associated with healthy salmon populations. The decline of salmon numbers throughout much of their southern range in North America has prompted concern that the elimination of this "conveyor belt" of nutrients and energy may fundamentally change the productivity of these coastal freshwater and terrestrial ecosystems, and consequently their ability to support wildlife, including salmon. If progress is to be made towards understanding and conserving the connection between migratory salmon and coastal ecosystems, scientists and decision-makers must explore and understand the vast temporal and spatial scales that characterize this relationship. DOI
