77.Dulvy, NK; Pacoureau, N; Rigby, CL; Pollom, RA; Jabado, RW; Ebert, DA; Finucci, B; Pollock, CM; Cheok, J; Derrick, DH; Herman, KB; Sherman, CS; VanderWright, WJ; Lawson, JM; Walls, RHL; Carlson, JK; Charvet, P; Bineesh, KK; Fernando, D; Ralph, GM; Matsushiba, JH; Hilton-Taylor, C; Fordham, SV; Simpfendorfer, CA. (2021) Overfishing drives over one-third of all sharks and rays toward a global extinction crisis.Curr. Biol. 31: 4773-+ Overfishing drives over one-third of all sharks and rays toward a global extinction crisis
The scale and drivers of marine biodiversity loss are being revealed by the International Union for Conservation of Nature (IUCN) Red List assessment process. We present the first global reassessment of 1,199 species in Class Chondrichthyes-sharks, rays, and chimeras. The first global assessment (in 2014) concluded that one-quarter (24%) of species were threatened. Now, 391 (32.6%) species are threatened with extinction. When this percentage of threat is applied to Data Deficient species, more than one-third (37.5%) of chondrichthyans are estimated to be threatened, with much of this change resulting from new information. Three species are Critically Endangered (Possibly Extinct), representing possibly the first globalmarine fish extinctions due to overfishing. Consequently, the chondrichthyan extinction rate is potentially 25 extinctions per million species years, comparable to that of terrestrial vertebrates. Overfishing is the universal threat affecting all 391 threatened species and is the sole threat for 67.3% of species and interacts with three other threats for the remaining third: loss and degradation of habitat (31.2% of threatened species), climate change (10.2%), and pollution (6.9%). Species are disproportionately threatened in tropical and subtropical coastal waters. Science-based limits on fishing, effective marine protected areas, and approaches that reduce or eliminate fishing mortality are urgently needed to minimize mortality of threatened species and ensure sustainable catch and trade of others. Immediate action is essential to prevent further extinctions and protect the potential for food security and ecosystem functions provided by this iconic lineage of predators. DOI PubMed
76. Finucci, B; Cheok, J; Ebert, DA; Herman, K; Kyne, PM; Dulvy, NK. (2021) Ghosts of the deep - Biodiversity, fisheries, and extinction risk of ghost sharks.Fish. Fish. 22: 391-412 Ghosts of the deep - Biodiversity, fisheries, and extinction risk of ghost sharks
by‐ catch; chimaera; chondrichthyan; data deficiency; holocephali; IUCN Red List; liver oil; sustainable fisheries
Ghost sharks (subclass Holocephali) remain a largely data-poor group of cartilaginous fishes. The general paucity of attention may partially be related to identification and unresolved taxonomic issues, occurrence in the deep oceans, and their low value and interest in fisheries (which some notable exceptions). Here, we synthesize and assess the extinction risk of all known extant ghost sharks (52 species) by applying the IUCN Red List of Threatened Species Categories and Criteria. Ghost sharks have a low proportion of threatened (8%) and Near Threatened (8%) species, with most species (69%) assessed as Least Concern. The group still exhibits some data deficiency (15%), and biological information is lacking for most species. Endemism is high, with 37% of species known from only one location or one country. Species richness was highest in the Northeast Atlantic, off the northwest coast of Africa (Morocco to Mauritania), the East China Sea, New Zealand and off the northwest coast of South America (Ecuador and Peru). Ghost sharks are predominately taken as by-catch, but some targeted fishing and/or retention for the liver oil trade occurs. Species-specific reporting, monitoring and management are required to assess population trends, and further investigation is needed on trade and use, particularly for higher risk species including the sicklefin chimaeras (genus Neoharriotta) and the American Elephantfish (Callorhynchus callorhynchus, Callorhinidae). DOI
75. Mann, ME; Hall, LJ; Dulvy, NK. (2021) Scientific impact in a changing world.Cell 184: 1407-1408 Scientific impact in a changing world
Measuring scientific success has traditionally involved numbers and statistics. However, due to an increasingly uncertain world, more than ever we need to measure the effect that science has on real-world scenarios. We asked researchers to share their points of view on what scientific impact means to them and how impact matters beyond the numbers. PubMed
74. Pacoureau, N; Rigby, CL; Kyne, PM; Sherley, RB; Winker, H; Carlson, JK; Fordham, SV; Barreto, R; Fernando, D; Francis, MP; Jabado, RW; Herman, KB; Liu, KM; Marshall, AD; Pollom, RA; Romanov, EV; Simpfendorfer, CA; Yin, JS; Kindsvater, HK; Dulvy, NK. (2021) Half a century of global decline in oceanic sharks and rays.Nature 589: 567-+ Half a century of global decline in oceanic sharks and rays
Overfishing is the primary cause of marine defaunation, yet declines in and increasing extinction risks of individual species are difficult to measure, particularly for the largest predators found in the high seas(1-3). Here we calculate two well-established indicators to track progress towards Aichi Biodiversity Targets and Sustainable Development Goals(4,5): the Living Planet Index (a measure of changes in abundance aggregated from 57 abundance time-series datasets for 18 oceanic shark and ray species) and the Red List Index (a measure of change in extinction risk calculated for all 31 oceanic species of sharks and rays). We find that, since 1970, the global abundance of oceanic sharks and rays has declined by 71% owing to an 18-fold increase in relative fishing pressure. This depletion has increased the global extinction risk to the point at which three-quarters of the species comprising this functionally important assemblage are threatened with extinction. Strict prohibitions and precautionary science-based catch limits are urgently needed to avert population collapse(6,7), avoid the disruption of ecological functions and promote species recovery(8,9). DOI PubMed
73. Wong, S; Bigman, JS; Dulvy, NK. (2021) The metabolic pace of life histories across fishes.Proc. R. Soc. B-Biol. Sci. 288 The metabolic pace of life histories across fishes
allometry; Bergmann's rule; gill oxygen limitation theory; metabolic theory of ecology; temperature-size rule
All life acquires energy through metabolic processes and that energy is subsequently allocated to life-sustaining functions such as survival, growth and reproduction. Thus, it has long been assumed that metabolic rate is related to the life history of an organism. Indeed, metabolic rate is commonly believed to set the pace of life by determining where an organism is situated along a fast-slow life-history continuum. However, empirical evidence of a direct interspecific relationship between metabolic rate and life histories is lacking, especially for ectothermic organisms. Here, we ask whether three life-history traits-maximum body mass, generation length and growth performance-explain variation in resting metabolic rate (RMR) across fishes. We found that growth performance, which accounts for the trade-off between growth rate and maximum body size, explained variation in RMR, yet maximum body mass and generation length did not. Our results suggest that measures of life history that encompass trade-offs between life-history traits, rather than traits in isolation, explain variation in RMR across fishes. Ultimately, understanding the relationship between metabolic rate and life history is crucial to metabolic ecology and has the potential to improve prediction of the ecological risk of data-poor species. DOI PubMed
72.Dulvy, NK; Yan, HF. (2020) Conservation: Goldilocks Nations for Restoring Reef Sharks.Curr. Biol. 30: R1415-R1418 Conservation: Goldilocks Nations for Restoring Reef Sharks
The first baited, video-based global survey of coral reef sharks reveals widespread depletion and functional extinction from eight nations. The authors identify priority 'Goldilocks' nations with the necessary combination of governance and shark abundance to recover depleted shark populations. DOI PubMed
71. Mull, CG; Yopak, KE; Dulvy, NK. (2020) Maternal Investment, Ecological Lifestyle, and Brain Evolution in Sharks and Rays.Am. Nat. 195: 1056-1069 Maternal Investment, Ecological Lifestyle, and Brain Evolution in Sharks and Rays
brain evolution; brain organization; oviparity; viviparity; shark; ray
Across vertebrates increased maternal investment (via increased pre- and postnatal provisioning) is associated with larger relative brain size, yet it remains unclear how brain organization is shaped by life history and ecology. Here, we tested whether maternal investment and ecological lifestyle are related to variation in brain size and organization across 100 chondrichthyans. We hypothesized that brain size and organization would vary with the level of maternal investment and habitat depth and complexity. We found that chondrichthyan brain organization varies along four main axes according to (1) absolute brain size, (2) relative diencephalon and mesencephalon size, (3) relative telencephalon and medulla size, and (4) relative cerebellum size. Increased maternal investment is associated with larger relative brain size, while ecological lifestyle is informative for variation between relative telencephalon and medulla size and relative cerebellum size after accounting for the independent effects of reproductive mode. Deepwater chondrichthyans generally provide low levels of yolk-only (lecithotrophic) maternal investment and have relatively small brains, predominantly composed of medulla (a major portion of the hindbrain), whereas matrotrophic chondrichthyans-which provide maternal provisioning beyond the initial yolk sac-found in coastal, reef, or shallow oceanic habitats have relatively large brains, predominantly composed of telencephalon (a major portion of the forebrain). We have demonstrated, for the first time, that both ecological lifestyle and maternal investment are independently associated with brain organization in a lineage with diverse life-history strategies and reproductive modes. DOI PubMed
70. Horswill, C; Kindsvater, HK; Juan-Jorda, MJ; Dulvy, NK; Mangel, M; Matthiopoulos, J. (2019) Global reconstruction of life-history strategies: A case study using tunas.J. Appl. Ecol. 56: 855-865 Global reconstruction of life-history strategies: A case study using tunas
Bayesian imputation; data limited; demography; fecundity; life-history theory; missing data; principal market tuna; Scombridae
Measuring the demographic parameters of exploited populations is central to predicting their vulnerability and extinction risk. However, current rates of population decline and species loss greatly outpace our ability to empirically monitor all populations that are potentially threatened. The scale of this problem cannot be addressed through additional data collection alone, and therefore it is a common practice to conduct population assessments based on surrogate data collected from similar species. However, this approach introduces biases and imprecisions that are difficult to quantify. Recent developments in hierarchical modelling have enabled missing values to be reconstructed based on the correlations between available life-history data, linking similar species based on phylogeny and environmental conditions. However, these methods cannot resolve life-history variability among populations or species that are closely placed spatially or taxonomically. Here, theoretically motivated constraints that align with life-history theory offer a new avenue for addressing this problem. We describe a Bayesian hierarchical approach that combines fragmented, multispecies and multi-population data with established life-history theory, in order to objectively determine similarity between populations based on trait correlations (life-history trade-offs) obtained from model fitting. We reconstruct 59 unobserved life-history parameters for 23 populations of tuna that sustain some of the world's most valuable fisheries. Testing by cross-validation across different scenarios indicated that life-histories were accurately reconstructed when information was available for other populations of the same species. The reconstruction of several traits was also accurate for species represented by a single population, although credible intervals increased dramatically.Synthesis and applications. The described Bayesian hierarchical method provides access to life-history traits that are difficult to measure directly and reconstructs missing life-history information useful for assessing populations and species that are directly or indirectly affected by human exploitation of natural resources. The method is particularly useful for examining populations that are spatially or taxonomically similar, and the reconstructed life-history strategies described for the principal market tunas have immediate application to the world-wide management of these fisheries. The described Bayesian hierarchical method provides access to life-history traits that are difficult to measure directly and reconstructs missing life-history information useful for assessing populations and species that are directly or indirectly affected by human exploitation of natural resources. The method is particularly useful for examining populations that are spatially or taxonomically similar, and the reconstructed life-history strategies described for the principal market tunas have immediate application to the world-wide management of these fisheries. DOI PubMed
69. Bigman, JS; Pardo, SA; Prinzing, TS; Dando, M; Wegner, NC; Dulvy, NK. (2018) Ecological lifestyles and the scaling of shark gill surface area.J. Morphol. 279 Ecological lifestyles and the scaling of shark gill surface area
allometry; ecomorphology; gill surface area; metabolism; scaling
Fish gill surface area varies across species and with respect to ecological lifestyles. The majority of previous studies only qualitatively describe gill surface area in relation to ecology and focus primarily on teleosts. Here, we quantitatively examined the relationship of gill surface area with respect to specific ecological lifestyle traits in elasmobranchs, which offer an independent evaluation of observed patterns in teleosts. As gill surface area increases ontogenetically with body mass, examination of how gill surface area varies with ecological lifestyle traits must be assessed in the context of its allometry (scaling). Thus, we examined how the relationship of gill surface area and body mass across 11 shark species from the literature and one species for which we made measurements, the Gray Smoothhound Mustelus californicus, varied with three ecological lifestyle traits: activity level, habitat, and maximum body size. Relative gill surface area (gill surface area at a specified body mass; here we used 5,000g, termed the 'standardized intercept') ranged from 4,724.98 to 35,694.39 cm(2) (mean and standard error: 17,796.65 +/- 2,948.61 cm(2)) and varied across species and the ecological lifestyle traits examined. Specifically, larger-bodied, active, oceanic species had greater relative gill surface area than smaller-bodied, less active, coastal species. In contrast, the rate at which gill surface area scaled with body mass (slope) was generally consistent across species (0.85 +/- 0.02) and did not differ statistically with activity level, habitat, or maximum body size. Our results suggest that ecology may influence relative gill surface area, rather than the rate at which gill surface area scales with body mass. Future comparisons of gill surface area and ecological lifestyle traits using the quantitative techniques applied in this study can provide further insight into patterns dictating the relationship between gill surface area, metabolism, and ecological lifestyle traits. DOI PubMed
68. Jabado, RW; Kyne, PM; Pollom, RA; Ebert, DA; Simpfendorfer, CA; Ralph, GM; Al Dhaheri, SS; Akhilesh, KV; Ali, K; Ali, MH; Al Mamari, TMS; Bineesh, KK; El Hassan, IS; Fernando, D; Grandcourt, EM; Khan, MM; Moore, ABM; Owfi, F; Robinson, DP; Romanov, E; Soares, AL; Spaet, JLY; Tesfamichael, D; Valinassab, T; Dulvy, NK. (2018) Troubled waters: Threats and extinction risk of the sharks, rays and chimaeras of the Arabian Sea and adjacent waters.Fish. Fish. 19 Troubled waters: Threats and extinction risk of the sharks, rays and chimaeras of the Arabian Sea and adjacent waters
chondrichthyans; extinction risk; fisheries; IUCN Red List; population decline; species diversity
The extinction risk of sharks, rays and chimaeras is higher than that for most other vertebrates due to low intrinsic population growth rates of many species and the fishing intensity they face. The Arabian Sea and adjacent waters border some of the most important chondrichthyan fishing and trading nations globally, yet there has been no previous attempt to assess the conservation status of species occurring here. Using IUCN Red List of Threatened Species Categories and Criteria and their guidelines for application at the regional level, we present the first assessment of extinction risk for 153 species of sharks, rays and chimaeras. Results indicate that this region, home to 15% of described chondrichthyans including 30 endemic species, has some of the most threatened chondrichthyan populations in the world. Seventy-eight species (50.9%) were assessed as threatened (Critically Endangered, Endangered or Vulnerable), and 27 species (17.6%) as Near Threatened. Twenty-nine species (19%) were Data Deficient with insufficient information to assess their status. Chondrichthyan populations have significantly declined due to largely uncontrolled and unregulated fisheries combined with habitat degradation. Further, there is limited political will and national and regional capacities to assess, manage, conserve or rebuild stocks. Outside the few deepsea locations that are lightly exploited, the prognosis for the recovery of most species is poor in the near-absence of management. Concerted national and regional management measures are urgently needed to ensure extinctions are avoided, the sustainability of more productive species is secured, and to avoid the continued thinning of the regional food security portfolio. DOI
67. Juan-Jorda, MJ; Murua, H; Arrizabalaga, H; Dulvy, NK; Restrepo, V. (2018) Report card on ecosystem-based fisheries management in tuna regional fisheries management organizations.Fish. Fish. 19 Report card on ecosystem-based fisheries management in tuna regional fisheries management organizations
bycatch; ecosystem impacts; ecosystem-based fisheries management; RFMO; sharks; tunas
International instruments of fisheries governance have set the core principles for the management of highly migratory fishes. We evaluated the progress of tuna Regional Fisheries Management Organizations (tRFMOs) in implementing the ecological component of ecosystem-based fisheries management (EBFM). We first developed a best case tRFMO for EBFM implementation. Second, we developed criteria to evaluate progress in applying EBFM against this best case tRFMO. We assessed progress of the following four ecological components: target species, bycatch species, ecosystem properties and trophic relationships, and habitats. We found that many of the elements necessary for an operational EBFM are already present, yet they have been implemented in an ad hoc way, without a long-term vision and a formalized plan. Overall, tRFMOs have made considerable progress monitoring the impacts of fisheries on target species, moderate progress for bycatch species, and little progress for ecosystem properties and trophic relationships and habitats. The tRFMOs appear to be halfway towards implementing the ecological component of EBFM, yet it is clear that the low-hanging fruit has been plucked and the more difficult, but surmountable, issues remain, notably the sustainable management of bycatch. All tRFMOs share the same challenge of developing a formal mechanism to better integrate ecosystem science and advice into management decisions. We hope to further discussion across the tRFMOs to inform the development of operational EBFM plans. DOI
66. Kindsvater, HK; Dulvy, NK; Horswill, C; Juan-Jorda, MJ; Mangel, M; Matthiopoulos, J. (2018) Overcoming the Data Crisis in Biodiversity Conservation.Trends Ecol. Evol. 33 Overcoming the Data Crisis in Biodiversity Conservation
How can we track population trends when monitoring data are sparse? Population declines can go undetected, despite ongoing threats. For example, only one of every 200 harvested species are monitored. This gapleads to uncertaintyabout the seriousness of declines and hampers effective conservation. Collecting more data is important, but we can also make better use of existing information. Prior knowledge of physiology, life history, and community ecology can be used to inform population models. Additionally, in multispecies models, information can be shared among taxa based on phylogenetic, spatial, or temporal proximity. By exploiting generalities across species that share evolutionary or ecological characteristics within Bayesian hierarchical models, we can fill crucial gaps in the assessment of species' status with unparalleled quantitative rigor. DOI PubMed
65. Leeney, RH; Mana, RR; Dulvy, NK. (2018) Fishers' ecological knowledge of sawfishes in the Sepik and Ramu rivers, northern Papua New Guinea.Endanger. Species Res. 36 Fishers' ecological knowledge of sawfishes in the Sepik and Ramu rivers, northern Papua New Guinea
Pristidae; Extinction risk; Anoxypristis cuspidata; Pristis pristis; Narrow sawfish; Largetooth sawfish; Interview surveys; Bycatch
Papua New Guinea (PNG) is geographically close to northern Australia, a key region tor 4 sawfish species. However, detailed data on sawtish presence in PNG are limited, particularly from the north coast. We conducted a short study to assess whether sawfishes are still present in 2 adjacent rivers - the Sepik and Ramu - in northern PNG. Interviews were conducted with fishers from villages along the Sepik River between Chambri Lake and the river mouth, as well as along the Keram River (a tributary of the Sepik) and the Ramu River. Landings by gillnet fishers at the mouth of the Sepik River were observed. At least 2 species, the narrow sawfish Anoxypristis cuspidata and the largetooth sawfish Pristis pristis, were present at the mouth of the Sepik River and were caught in gillnets used to target sharks and croakers (Sciaenidae). Largetooth sawfish aie still captured by fishers in the freshwater reaches of the Sepik, Ramu, and Keram rivers. The fins of sawfishes and other elasmobranchs provide a source of income, and sawfish meat is eaten locally or sold. The Sepik River and surrounding coastline remains important habitat for sawfishes; however, most interviewees reported a decline in sawfish catches over the course of their lifetimes. These findings corroborate existing evidence suggesting that PNG remains a global stronghold for sawfishes. Immediate collaboration with fishing communities and PNG's fisheries and conservation authorities is needed to ensure that any sawfish catches and habitats are appropriately managed so that populations do not decline further. DOI
64. Pardo, SA; Cooper, AB; Reynolds, JD; Dulvy, NK. (2018) Quantifying the known unknowns: estimating maximum intrinsic rate of population increase in the face of uncertainty.ICES J. Mar. Sci. 75 Quantifying the known unknowns: estimating maximum intrinsic rate of population increase in the face of uncertainty
bycatch; Carcharhinus; Chondrichthyes; demography; Elasmobranchii; reference points; risk assessment
Sensitivity to overfishing is often estimated using simple models that depend upon life history parameters, especially for species lacking detailed biological information. Yet, there has been little exploration of how uncertainty in life history parameters can influence demographic parameter estimates and therefore fisheries management options. We estimate the maximum intrinsic rate of population increase (rmax) for ten coastal carcharhiniform shark populations using an unstructured life history model that explicitly accounts for uncertainty in life history parameters. We evaluate how the two directly estimated parameters, age at maturity amat and annual reproductive output b, most influenced rmax estimates. Uncertainty in age at maturity values was low, but resulted in moderate uncertainty in rmax estimates. The model was sensitive to uncertainty in annual reproductive output for the least fecund species with fewer than 5 female offspring per year, which is not unusual for large elasmobranchs, marine mammals, and seabirds. Managers and policy makers should be careful to restrict mortality on species with very low annual reproductive output< 2 females per year. We recommend elasmobranch biologists to measure frequency distributions of litter sizes (rather than just a range) as well as improving estimates of natural mortality of data-poor elasmobranchs. DOI
63. Stein, RW; Mull, CG; Kuhn, TS; Aschliman, NC; Davidson, LNK; Joy, JB; Smith, GJ; Dulvy, NK; Mooers, AO. (2018) Global priorities for conserving the evolutionary history of sharks, rays and chimaeras.Nat. Ecol. Evol. 2 Global priorities for conserving the evolutionary history of sharks, rays and chimaeras
In an era of accelerated biodiversity loss and limited conservation resources, systematic prioritization of species and places is essential. In terrestrial vertebrates, evolutionary distinctness has been used to identify species and locations that embody the greatest share of evolutionary history. We estimate evolutionary distinctness for a large marine vertebrate radiation on a dated taxon-complete tree for all 1,192 chondrichthyan fishes (sharks, rays and chimaeras) by augmenting a new 610-species molecular phylogeny using taxonomic constraints. Chondrichthyans are by far the most evolutionarily distinct of all major radiations of jawed vertebrates-the average species embodies 26 million years of unique evolutionary history. With this metric, we identify 21 countries with the highest richness, endemism and evolutionary distinctness of threatened species as targets for conservation prioritization. On average, threatened chondrichthyans are more evolutionarily distinct-further motivating improved conservation, fisheries management and trade regulation to avoid significant pruning of the chondrichthyan tree of life. DOI PubMed
62. Anderson, SC; Branch, TA; Cooper, AB; Dulvy, NK. (2017) Black-swan events in animal populations.Proceedings of the National Academy of Sciences of the United States of America 114: 3252-3257 Black-swan events in animal populations
mass mortality; ecological surprises; population dynamics; die-offs; ecological risk
Black swans are improbable events that nonetheless occur-often with profound consequences. Such events drive important transitions in social systems (e.g., banking collapses) and physical systems (e.g., earthquakes), and yet it remains unclear the extent to which ecological population numbers buffer or suffer from such extremes. Here, we estimate the prevalence and direction of black-swan events (heavy-tailed process noise) in 609 animal populations after accounting for population dynamics (productivity, density dependence, and typical stochasticity). We find strong evidence for black-swan events in similar to 4% of populations. These events occur most frequently for birds (7%), mammals (5%), and insects (3%) and are not explained by any life-history covariates but tend to be driven by external perturbations such as climate, severe winters, predators, parasites, or the combined effect of multiple factors. Black-swan events manifest primarily as population die-offs and crashes (86%) rather than unexpected increases, and ignoring heavy-tailed process noise leads to an underestimate in the magnitude of population crashes. We suggest modelers consider heavy-tailed, downward-skewed probability distributions, such as the skewed Student t used here, when making forecasts of population abundance. Our results demonstrate the importance of both modeling heavy-tailed downward events in populations, and developing conservation strategies that are robust to ecological surprises. DOI
60. Blanchard, JL; Watson, RA; Fulton, EA; Cottrell, RS; Nash, KL; Bryndum-Buchholz, A; Buchner, M; Carozza, DA; Cheung, WWL; Elliott, J; Davidson, LNK; Dulvy, NK; Dunne, JP; Eddy, TD; Galbraith, E; Lotze, HK; Maury, O; Muller, C; Tittensor, DP; Jennings, S. (2017) Linked sustainability challenges and trade-offs among fisheries, aquaculture and agriculture.Nature Ecology & Evolution 1: 1240-1249 Linked sustainability challenges and trade-offs among fisheries, aquaculture and agriculture
Fisheries and aquaculture make a crucial contribution to global food security, nutrition and livelihoods. However, the UN Sustainable Development Goals separate marine and terrestrial food production sectors and ecosystems. To sustainably meet increasing global demands for fish, the interlinkages among goals within and across fisheries, aquaculture and agriculture sectors must be recognized and addressed along with their changing nature. Here, we assess and highlight development challenges for fisheries-dependent countries based on analyses of interactions and trade-offs between goals focusing on food, biodiversity and climate change. We demonstrate that some countries are likely to face double jeopardies in both fisheries and agriculture sectors under climate change. The strategies to mitigate these risks will be context-dependent, and will need to directly address the trade-offs among Sustainable Development Goals, such as halting biodiversity loss and reducing poverty. Countries with low adaptive capacity but increasing demand for food require greater support and capacity building to transition towards reconciling trade-offs. Necessary actions are context-dependent and include effective governance, improved management and conservation, maximizing societal and environmental benefits from trade, increased equitability of distribution and innovation in food production, including continued development of low input and low impact aquaculture. DOI
59. Davidson, LNK; Dulvy, NK. (2017) Global marine protected areas to prevent extinctions.Nature Ecology & Evolution 1 Global marine protected areas to prevent extinctions
One goal of global marine protected areas (MPAs) is to ensure they represent a breadth of taxonomic biodiversity. Ensuring representation of species in MPAs, however, would require protecting vast areas of the global oceans and does not explicitly prioritize species of conservation concern. When threatened species are considered, a recent study found that only a small fraction of their geographic ranges are within the global MPA network. Which global marine areas, and what conservation actions beyond MPAs could be prioritized to prevent marine extinctions (Convention on Biological Diversity Aichi Target 12), remains unknown. Here, we use systematic conservation planning approaches to prioritize conservation actions for sharks, rays and chimaeras (class Chondrichthyes). We use chondrichthyans as they have the highest proportion of threatened species of any marine class. We find that expanding the MPA network by 3% in 70 nations would cover half of the geographic range of 99 imperilled endemic chondrichthyans. Our hotspot analysis reveals that just 12 nations harbour more than half (53) of the imperilled endemics. Four of these hotspot nations are within the top ten chondrichthyan fishing nations in the world, but are yet to implement basic chondrichthyan fisheries management. Given their geopolitical realities, conservation action for some countries will require relief and reorganization to enable sustainable fisheries and species protection. DOI
58.Dulvy, NK; Simpfendorfer, CA; Davidson, LNK; Fordham, SV; Brautigam, A; Sant, G; Welch, DJ. (2017) Challenges and Priorities in Shark and Ray Conservation.Curr. Biol. 27: R565-R572 Challenges and Priorities in Shark and Ray Conservation
Sharks, rays, and chimaeras (Class Chondrichthyes; herein 'sharks') are the earliest extant jawed vertebrates and exhibit some of the greatest functional diversity of all vertebrates. Ecologically, they influence energy transfer vertically through trophic levels and sometimes trophic cascades via direct consumption and predation risk. Through movements and migrations, they connect horizontally and temporally across habitats and ecosystems, integrating energy flows at large spatial scales and across time. This connectivity flows from ontogenetic growth in size and spatial movements, which in turn underpins their relatively low reproductive rates compared with other exploited ocean fishes. Sharks are also ecologically and demographically diverse and are taken in a wide variety of fisheries for multiple products (e.g. meat, fins, teeth, and gills). Consequently, a range of fisheries management measures are generally preferable to 'silver bullet' and 'one size fits all' conservation actions. Some species with extremely low annual reproductive output can easily become endangered and hence require strict protections to minimize mortality. Other, more prolific species can withstand fishing over the long term if catches are subject to effective catch limits throughout the species' range. We identify, based on the IUCN Red List status, 64 endangered species in particular need of new or stricter protections and 514 species in need of improvements to fisheries management. We designate priority countries for such actions, recognizing the widely differing fishing pressures and conservation capacity. We hope that this analysis assists efforts to ensure this group of ecologically important and evolutionarily distinct animals can support both ocean ecosystems and human activities in the future. DOI
57. Fernandes, PG; Ralph, GM; Nieto, A; Criado, MG; Vasilakopoulos, P; Maravelias, CD; Cook, RM; Pollom, RA; Kovacic, M; Pollard, D; Farrell, ED; Florin, AB; Polidoro, BA; Lawson, JM; Lorance, P; Uiblein, F; Craig, M; Allen, DJ; Fowler, SL; Walls, RHL; Comeros-Raynal, MT; Harvey, MS; Dureuil, M; Biscoito, M; Pollock, C; Phillips, SRM; Ellis, JR; Papaconstantinou, C; Soldo, A; Keskin, C; Knudsen, SW; de Sola, LG; Serena, F; Collette, BB; Nedreaas, K; Stump, E; Russell, BC; Garcia, S; Afonso, P; Jung, ABJ; Alvarez, H; Delgado, J; Dulvy, NK; Carpenter, KE. (2017) Coherent assessments of Europe's marine fishes show regional divergence and megafauna loss.Nature Ecology & Evolution 1 Coherent assessments of Europe's marine fishes show regional divergence and megafauna loss
Europe has a long tradition of exploiting marine fishes and is promoting marine economic activity through its Blue Growth strategy. This increase in anthropogenic pressure, along with climate change, threatens the biodiversity of fishes and food security. Here, we examine the conservation status of 1,020 species of European marine fishes and identify factors that contribute to their extinction risk. Large fish species (greater than 1.5 m total length) are most at risk; half of these are threatened with extinction, predominantly sharks, rays and sturgeons. This analysis was based on the latest International Union for Conservation of Nature (IUCN) European regional Red List of marine fishes, which was coherent with assessments of the status of fish stocks carried out independently by fisheries management agencies: no species classified by IUCN as threatened were considered sustainable by these agencies. A remarkable geographic divergence in stock status was also evident: in northern Europe, most stocks were not overfished, whereas in the Mediterranean Sea, almost all stocks were overfished. As Europe proceeds with its sustainable Blue Growth agenda, two main issues stand out as needing priority actions in relation to its marine fishes: the conservation of marine fish megafauna and the sustainability of Mediterranean fish stocks. DOI
56. Lawson, JM; Fordham, SV; O'Malley, MP; Davidson, LNK; Walls, RHL; Heupel, MR; Stevens, G; Fernando, D; Budziak, A; Simpfendorfer, CA; Ender, I; Francis, MP; di Sciara, GN; Dulvy, NK. (2017) Sympathy for the devil: a conservation strategy for devil and manta rays.PeerJ 5 Sympathy for the devil: a conservation strategy for devil and manta rays
Elasmobranch; Conservation planning; Convention on the International Trade in Endangered Species (CITES); Convention on the Conservation of Migratory Species of Wild Animals (CMS); Extinction risk International Union for the Conservation of Nature (IUCN); Multilateral Environmental Agreements (MEAs); Tourism; Wildlife trade; Charismatic species
Background. International trade for luxury products, medicines, and tonics poses a threat to both terrestrial and marine wildlife. The demand for and consumption of gill plates (known as Peng Yu Sai, "Fish Gill of Mobulid Ray") from devil and manta rays (subfamily Mobulinae, collectively referred to as mobulids) poses a significant threat to these marine fishes because of their extremely low productivity. The demand for these gill plates has driven an international trade supplied by largely unmonitored and unregulated catches from target, and incidental fisheries around the world. Scientific research, conservation campaigns, and legal protections for devil rays have lagged behind those for manta rays despite similar threats across all mobufids. Methods. To investigate the difference in attention given to devil rays and manta rays, we examined trends in the scientific literature and updated species distribution maps for all mobufids. Using available information on target and incidental fisheries, and gathering information on fishing and trade regulations (at international, national, and territorial levels), we examined how threats and protective measures overlap with species distribution. We then used a species conservation planning approach to develop the Global Devil and Manta Ray Conservation Strategy, specifying a vision, goals, objectives, and actions to advance the knowledge and protection of both devil and manta rays. Results and Discussion. Our literature review revealed that there had been nearly 2.5-times more "manta"-titled publications, than "mobula" or "devil ray"-titled publications over the Past 4.5 years (January 2012 June 2016). The majority of these recent publications were reports on occurrence of mobulid species. These publications contributed to updated Area of Occupancy and Extent of Occurrence maps which showed expanded distributions for most mobulid species and overlap between the two genera. While several international protections have recently expanded to include all mobulids, there remains a greater number of national, state, and territory-level protections for manta rays compared to devil rays. We hypothesize that there are fewer scientific publications and regulatory protections for devil rays due primarily to perceptions of charisma that favour manta rays. We suggest that the well-established species conservation framework used here offers an objective solution to close this gap. To advance the goals of the conservation strategy we highlight opportunities for parity in protection and suggest solutions to help reduce target and by catch fisheries. DOI
54. Arthington, AH; Dulvy, NK; Gladstone, W; Winfield, IJ. (2016) Fish conservation in freshwater and marine realms: status, threats and management.Aquatic Conservation-Marine and Freshwater Ecosystems 26: 838-857 Fish conservation in freshwater and marine realms: status, threats and management
extinction risk; threats; correlates of risk; conservation reserves; restoration; recovery plans; fisheries management; climate change
1. Despite the disparities in size and volume of marine and freshwater realms, a strikingly similar number of species is found in each - with 15 150 Actinopterygian fishes in fresh water and 14 740 in the marine realm. Their ecological and societal values are widely recognized yet many marine and freshwater fishes increasingly risk local, regional or global extinction. 2. The prevailing threats in aquatic systems are habitat loss and degradation, invasive species, pollution, over-exploitation and climate change. Unpredictable synergies with climate change greatly complicate the impacts of other stressors that threaten many marine and freshwater fishes. 3. Isolated and fragmented habitats typically present the most challenging environments for small, specialized freshwater and marine fishes, whereas overfishing is by far the greatest threat to larger marine and freshwater species. Species that migrate within or between freshwater and marine realms may face high catchability in predictable migration bottlenecks, and degradation of breeding habitat, feeding habitat or the intervening migration corridors. 4. Conservation reserves are vital to protect species-rich habitats, important radiations, and threatened endemic species. Integration of processes that connect terrestrial, freshwater and marine protected areas promises more effective conservation outcomes than disconnected reserves. Diadromous species in particular require more attention in aquatic restoration and conservation planning across disparate government agencies. 5. Human activities and stressors that increasingly threaten freshwater and marine fishes must be curbed to avoid a wave of extinctions. Freshwater recovery programmes range from plans for individual species to recovery of entire basin faunas. Reducing risks to threatened marine species in coastal habitats also requires conservation actions at multiple scales. Most of the world's larger economically important fisheries are relatively well-monitored and well-managed but there are urgent needs to curb fishing mortality and minimize catch of the most endangered species in both realms. Copyright (C) 2016 John Wiley & Sons, Ltd. DOI
53. Collen, B; Dulvy, NK; Gaston, KJ; Gardenfors, U; Keith, DA; Punt, AE; Regan, HM; Bohm, M; Hedges, S; Seddon, M; Butchart, SHM; Hilton-Taylor, C; Hoffmann, M; Bachman, SP; Akcakaya, HR. (2016) Clarifying misconceptions of extinction risk assessment with the IUCN Red List.Biology Letters 12 Clarifying misconceptions of extinction risk assessment with the IUCN Red List
climate change; geographical range; population decline; rarity; spatial autocorrelation; uncertainty
The identification of species at risk of extinction is a central goal of conservation. As the use of data compiled for IUCN Red List assessments expands, a number of misconceptions regarding the purpose, application and use of the IUCN Red List categories and criteria have arisen. We outline five such classes of misconception; the most consequential drive proposals for adapted versions of the criteria, rendering assessments among species incomparable. A key challenge for the future will be to recognize the point where understanding has developed so markedly that it is time for the next generation of the Red List criteria. We do not believe we are there yet but, recognizing the need for scrutiny and continued development of Red Listing, conclude by suggesting areas where additional research could be valuable in improving the understanding of extinction risk among species. DOI
52. Croll, DA; Dewar, H; Dulvy, NK; Fernando, D; Francis, MP; Galvan-Magana, F; Hall, M; Heinrichs, S; Marshall, A; Mccauley, D; Newton, KM; Notarbartolo-Di-Sciara, G; O'Malley, M; O'Sullivan, J; Poortvliet, M; Roman, M; Stevens, G; Tershy, BR; White, WT. (2016) Vulnerabilities and fisheries impacts: the uncertain future of manta and devil rays.Aquatic Conservation-Marine and Freshwater Ecosystems 26: 562-575 Vulnerabilities and fisheries impacts: the uncertain future of manta and devil rays
coastal; ocean; conservation evaluation; endangered species; fish; fishing
1. Manta and devil rays of the subfamily Mobulinae (mobulids) are rarely studied, large, pelagic elasmobranchs, with all eight of well-evaluated species listed on the IUCN Red List as threatened or near threatened. 2. Mobulids have life history characteristics (matrotrophic reproduction, extremely low fecundity, and delayed age of first reproduction) that make them exceptionally susceptible to overexploitation. 3. Targeted and bycatch mortality from fisheries is a globally important and increasing threat, and targeted fisheries are incentivized by the high value of the global trade in mobulid gill plates. 4. Fisheries bycatch of mobulids is substantial in tuna purse seine fisheries. 5. Thirteen fisheries in 12 countries specifically targeting mobulids, and 30 fisheries in 23 countries with mobulid bycatch were identified. 6. Aside from a few recently enacted national restrictions on capture, there is no comprehensive monitoring, assessment or control of mobulid fisheries or bycatch. Recent listing through the Convention on the International Trade in Endangered Species (CITES) may benefit mobulids of the genus Manta (manta rays), but none of the mobulids in the genus Mobula (devil rays) are protected. 7. The relative economic costs of catch mitigation are minimal, particularly compared with a broad range of other, more complicated, marine conservation issues. Copyright (C) 2015 John Wiley & Sons, Ltd. DOI
51. Davidson, LNK; Krawchuk, MA; Dulvy, NK. (2016) Why have global shark and ray landings declined: improved management or overfishing?Fish and Fisheries 17: 438-458 Why have global shark and ray landings declined: improved management or overfishing?
Conservation; Convention on International Trade in Endangered Species; elasmobranch; fin trade; fishing mortality; National Plans of Action
Global chondrichthyan (shark, ray, skate and chimaera) landings, reported to the United Nations Food and Agriculture Organization (FAO), peaked in 2003 and in the decade since have declined by almost 20%. In the FAO's 2012 'State of the World's Fisheries and Aquaculture' report, the authors 'hoped' the reductions in landings were partially due to management implementation rather than population decline. Here, we tested their hypothesis. Post-peak chondrichthyan landings trajectories from 126 countries were modelled against seven indirect and direct fishing pressure measures and eleven measures of fisheries management performance, while accounting for ecosystem attributes. We found the recent improvement in international or national fisheries management was not yet strong enough to account for the recent decline in chondrichthyan landings. Instead, the landings declines were more closely related to fishing pressure and ecosystem attribute measures. Countries with the greatest declines had high human coastal population sizes or high shark and ray meat exports such as Pakistan, Sri Lanka and Thailand. While important progress had been made, country-level fisheries management measures did not yet have the strength or coverage to halt overfishing and avert population declines of chondrichthyans. Increased implementation of legally binding operational fisheries management and species-specific reporting is urgently required to avoid declines and ensure fisheries sustainability and food security. DOI
50.Dulvy, NK; Davidson, LNK; Kyne, PM; Simpfendorfer, CA; Harrison, LR; Carlson, JK; Fordham, SV. (2016) Ghosts of the coast: global extinction risk and conservation of sawfishes.Aquatic Conservation-Marine and Freshwater Ecosystems 26: 134-153 Ghosts of the coast: global extinction risk and conservation of sawfishes
estuary; functional redundancy; habitat degradation and loss; mangrove; range contraction
1. Sawfish are arguably the world's most imperilled marine fishes. All five species are classified as highly threatened with extinction: three are Critically Endangered (smalltooth sawfish Pristis pectinata, largetooth sawfish Pristis pristis, and green sawfish Pristis zijsron); two are Endangered (narrow sawfish Anoxypristis cuspidata, and dwarf sawfish Pristis clavata). 2. Sawfishes are threatened primarily due to a combination of their low intrinsic rates of population increase, high catchability in fisheries, and high value. Sawfishes are among the world's largest marine fishes, and they are caught by a wide range of fishing gears owing to their tooth-studded rostra being easily entangled. Sawfish fins are some of the most valuable for shark fin soup, and their rostra have long been traded as curios. In addition, they inhabit shallow coastal waters, estuaries, and rivers of the tropics and subtropics, down to a maximum depth rarely exceeding 100 m and are associated with threatened mangrove and seagrass habitats. 3. Historically, sawfishes were distributed in the coastal waters of 90 countries and territories. Over the past century, their geographic distribution has been greatly diminished. For example, the smalltooth sawfish is now found in <20% of its former range. Globally, sawfishes are now entirely absent from 20 countries; 43 countries have lost at least one species. 4. Sawfishes are legally protected, to some degree, in 16 of the 90 range states. These safeguards encompass, on average, 81% of their Extant distribution; however, the quality and breadth of protection varies dramatically across countries and species. Smalltooth sawfish currently has the least amount of such coverage of only half (49%) of Extant distribution. 5. he global conservation strategy specifies actions to protect sawfish and their habitats. Such actions are urgently warranted to avoid global extinction and to restore robust populations for the benefit of coastal ecosystem function and biodiversity. (c) 2014 The Authors. Aquatic Conservation: Marine and Freshwater Ecosystems published by John Wiley & Sons, Ltd. DOI
49. Kindsvater, HK; Mangel, M; Reynolds, JD; Dulvy, NK. (2016) Ten principles from evolutionary ecology essential for effective marine conservation.Ecology and Evolution 6: 2125-2138 Ten principles from evolutionary ecology essential for effective marine conservation
Conservation; demography; extinction risk; fish; life-history theory; management; reference points; sustainability
Sustainably managing marine species is crucial for the future health of the human population. Yet there are diverse perspectives concerning which species can be exploited sustainably, and how best to do so. Motivated by recent debates in the published literature over marine conservation challenges, we review ten principles connecting life-history traits, population growth rate, and density-dependent population regulation. We introduce a framework for categorizing life histories, POSE (Precocial-Opportunistic-Survivor-Episodic), which illustrates how a species' life-history traits determine a population's compensatory capacity. We show why considering the evolutionary context that has shaped life histories is crucial to sustainable management. We then review recent work that connects our framework to specific opportunities where the life-history traits of marine species can be used to improve current conservation practices. DOI
48. McClenachan, L; Cooper, AB; Dulvy, NK. (2016) Rethinking Trade-Driven Extinction Risk in Marine and Terrestrial Megafauna.Current Biology 26: 1640-1646 Rethinking Trade-Driven Extinction Risk in Marine and Terrestrial Megafauna
Large animals hunted for the high value of their parts (e.g., elephant ivory and shark fins) are at risk of extinction due to both intensive international trade pressure and intrinsic biological sensitivity. However, the relative role of trade, particularly in non-perishable products, and biological factors in driving extinction risk is not well understood [1-4]. Here we identify a taxonomically diverse group of >100 marine and terrestrial megafauna targeted for international luxury markets; estimate their value across three points of sale; test relationships among extinction risk, high value, and body size; and quantify the effects of two mitigating factors: poaching fines and geographic range size. We find that body size is the principal driver of risk for lower value species, but that this biological pattern is eliminated above a value threshold, meaning that the most valuable species face a high extinction risk regardless of size. For example, once mean product values exceed US$12,557 kg(-1), body size no longer drives risk. Total value scales with size for marine animals more strongly than for terrestrial animals, incentivizing the hunting of large marine individuals and species. Poaching fines currently have little effect on extinction risk; fines would need to be increased 10- to 100-fold to be effective. Large geographic ranges reduce risk for terrestrial, but not marine, species, whose ranges are ten times greater. Our results underscore both the evolutionary and ecosystem consequences of targeting large marine animals and the need to geographically scale up and prioritize conservation of high-value marine species to avoid extinction. DOI
47. Pardo, SA; Kindsvater, HK; Cuevas-Zimbron, E; Sosa-Nishizaki, O; Perez-Jimenez, JC; Dulvy, NK. (2016) Growth, productivity, and relative extinction risk of a data-sparse devil ray.Scientific Reports 6 Growth, productivity, and relative extinction risk of a data-sparse devil ray
Devil rays (Mobula spp.) face intensifying fishing pressure to meet the ongoing international demand for gill plates. The paucity of information on growth, mortality, and fishing effort for devil rays make quantifying population growth rates and extinction risk challenging. Furthermore, unlike manta rays (Manta spp.), devil rays have not been listed on CITES. Here, we use a published size-at-age dataset for the Spinetail Devil Ray (Mobula japanica), to estimate somatic growth rates, age at maturity, maximum age, and natural and fishing mortality. We then estimate a plausible distribution of the maximum intrinsic population growth rate (r(max)) and compare it to 95 other chondrichthyans. We find evidence that larger devil ray species have low somatic growth rate, low annual reproductive output, and low maximum population growth rates, suggesting they have low productivity. Fishing rates of a small-scale artisanal Mexican fishery were comparable to our estimate of r(max), and therefore probably unsustainable. Devil ray r(max) is very similar to that of manta rays, indicating devil rays can potentially be driven to local extinction at low levels of fishing mortality and that a similar degree of protection for both groups is warranted. DOI
46. Pardo, SA; Kindsvater, HK; Reynolds, JD; Dulvy, NK. (2016) Maximum intrinsic rate of population increase in sharks, rays, and chimaeras: the importance of survival to maturity.Canadian Journal of Fisheries and Aquatic Sciences 73: 1159-1163 Maximum intrinsic rate of population increase in sharks, rays, and chimaeras: the importance of survival to maturity
The maximum intrinsic rate of population increase (r(max)) is a commonly estimated demographic parameter used in assessments of extinction risk. In teleosts, r(max) can be calculated using an estimate of spawners per spawner, but for chondrichthyans, most studies have used annual reproductive output (b) instead. This is problematic as it effectively assumes all juveniles survive to maturity. Here, we propose an updated r(max) equation that uses a simple mortality estimator that also accounts for survival to maturity: the reciprocal of average life-span. For 94 chondrichthyans, we now estimate that r(max) values are on average 10% lower than previously published. Our updated r(max) estimates are lower than previously published for species that mature later relative to maximum age and those with high annual fecundity. The most extreme discrepancies in r(max) values occur in species with low age at maturity and low annual reproductive output. Our results indicate that chondrichthyans that mature relatively later in life, and to a lesser extent those that are highly fecund, are less resilient to fishing than previously thought. DOI
45. Trebilcou, R; Dulvy, NK; Anderson, SC; Salomon, AK. (2016) The paradox of inverted biomass pyramids in kelp forest fish communities.Proceedings of the Royal Society B-Biological Sciences 283 The paradox of inverted biomass pyramids in kelp forest fish communities
ecosystem baseline; fractionation; habitat complexity; species interaction; size spectra; stable isotope analysis
Theory predicts that bottom-heavy biomass pyramids or 'stacks' should predominate in real-world communities if trophic-level increases with body size (mean predator-to-prey mass ratio (PPMR) more than 1). However, recent research suggests that inverted biomass pyramids (IBPs) characterize relatively pristine reef fish communities. Here, we estimated the slope of a kelp forest fish community biomass spectrum from underwater visual surveys. The observed biomass spectrum slope is strongly positive, reflecting an IBP. This is incongruous with theory because this steep positive slope would only be expected if trophic position decreased with increasing body size (consumer-to-resource mass ratio, less than 1). We then used delta N-15 signatures of fish muscle tissue to quantify the relationship between trophic position and body size and instead detected strong evidence for the opposite, with PPMR 1650 (50% credible interval 280-12 000). The natural history of kelp forest reef fishes suggests that this paradox could arise from energetic subsidies in the form of movement of mobile consumers across habitats, and from seasonally pulsed production inputs at small body sizes. There were four to five times more biomass at large body sizes (1-2 kg) than would be expected in a closed steady-state community providing a measure of the magnitude of subsidies. DOI
44. 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
43. d'Eon-Eggertson, F; Dulvy, NK; Peterman, RM. (2015) Reliable Identification of Declining Populations in an Uncertain World.Conservation Letters 8: 86-96 Reliable Identification of Declining Populations in an Uncertain World
Decline indicators; error rates; IUCN; Monte Carlo simulation; extinction-risk assessment; process variation; observation error
Assessments of extinction risk based on population declines are widely used, yet scientists have little quantitative understanding of their reliability. Incorrectly classifying whether a population is declining or not can lead to inappropriate conservation actions or management measures, with potentially profound societal costs. Here we evaluate key causes of misclassification of decline status and assess the reliability of 20 decline metrics using a stochastic model to simulate time series of population abundance of sockeye salmon (Oncorhynchus nerka). We show that between-year variability in population productivity (process variation) and, to a lesser extent, variability in abundance estimates (observation error) are important causes of unreliable identification of population status. We found that using all available data, rather than just the most recent three generations, consistently improved the reliability of risk assessments. The approach outlined here can improve understanding of the reliability of risk assessments, thereby reducing concerns that may impede their use for exploited taxa such as marine fishes. DOI
42.Dulvy, NK; Kindsvater, HK. (2015) Recovering the potential of coral reefs.Nature 520: 304-305 Recovering the potential of coral reefs
An analysis of fish declines in coral reefs shows that simple fishing limits and implementation of marine protected areas can be enough to support recovery of coral ecosystem resilience. PubMed
40. Juan-Jorda, MJ; Mosqueira, I; Freire, J; Dulvy, NK. (2015) Population declines of tuna and relatives depend on their speed of life.Proceedings of the Royal Society B-Biological Sciences 282 Population declines of tuna and relatives depend on their speed of life
vulnerability; declines; life histories; fishes; fishing mortality; scombrids
Larger-bodied species in a wide range of taxonomic groups including mammals, fishes and birds tend to decline more steeply and are at greater risk of extinction. Yet, the diversity in life histories is governed not only by body size, but also by time-related traits. A key question is whether this size-dependency of vulnerability also holds, not just locally, but globally across a wider range of environments. We test the relative importance of size-and time-related life-history traits and fishing mortality in determining population declines and current exploitation status in tunas and their relatives. We use high-quality datasets of half a century of population trajectories combined with population-level fishing mortalities and life-history traits. Time-related traits (e.g. growth rate), rather than size-related traits (e.g. maximum size), better explain the extent and rate of declines and current exploitation status across tuna assemblages, after controlling for fishing mortality. Consequently, there is strong geographical patterning in population declines, such that populations with slower life histories (found at higher cooler latitudes) have declined most and more steeply and have a higher probability of being overfished than populations with faster life histories (found at tropical latitudes). Hence, the strong, temperature-driven, latitudinal gradients in life-history traits may underlie the global patterning of population declines, fisheries collapses and local extinctions. DOI
39. Keith, D; Akcakaya, HR; Butchart, SHM; Collen, B; Dulvy, NK; Holmes, EE; Hutchings, JA; Keinath, D; Schwartz, MK; Shelton, AO; Waples, RS. (2015) Temporal correlations in population trends: Conservation implications from time-series analysis of diverse animal taxa.Biological Conservation 192: 247-257 Temporal correlations in population trends: Conservation implications from time-series analysis of diverse animal taxa
Population growth rate; Population trend; Endangered species; Time series; Vertebrates
Population trends play a large role in species risk assessments and conservation planning, and species are often considered threatened if their recent rate of decline meets certain thresholds, regardless how large the population is. But how reliable an indicator of extinction risk is a single estimate of population trend? Given the integral role this decline-based approach has played in setting conservation priorities, it is surprising that it has undergone little empirical scrutiny. We compile an extensive global dataset of time series of abundance data for over 1300 vertebrate populations to provide the first major test of the predictability of population growth rates in nature. We divided each time series into assessment and response periods and examined the correlation between growth rates in the two time periods. In birds, population declines tended to be followed by further declines, but mammals, salmon, and other bony fishes showed the opposite pattern: past declines were associated with subsequent population increases, and vice versa. Furthermore, in these taxa subsequent growth rates were higher when initial declines were more severe. These patterns agreed with data simulated under a null model for a dynamically stable population experiencing density dependence. However, this type of result could also occur if conservation actions positively affected the population following initial declines a scenario that our data were too limited to rigorously evaluate. This ambiguity emphasizes the importance of understanding the underlying causes of population trajectories in drawing inferences about rates of decline in abundance. Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/). DOI
38. Shelton, AO; Hutchings, JA; Waples, RS; Keith, DM; Akcakaya, HR; Dulvy, NK. (2015) Maternal age effects on Atlantic cod recruitment and implications for future population trajectories.ICES Journal of Marine Science 72: 1769-1778 Maternal age effects on Atlantic cod recruitment and implications for future population trajectories
age-structure; age truncation; maternal effects; recruitment; Ricker; productivity
Exploited fish populations frequently exhibit truncated age-structure. To address a basic question in fisheries science and conservation biology-how does age truncation affect population dynamics and productivity?-we explored the effect of age-structure on recruitment dynamics of ten stocks of Atlantic cod (Gadus morhua). Based on six alternative stock-recruitment relationships, we compared models that included and excluded maternal age-structure effects on recruitment. In all ten stocks, a recruitment model that included a maternal age-dependent effect was preferred over the standard Ricker model and in seven of the ten stocks, the preferred statistical model included a positive effect of either maternal age or mass on recruitment. Simulations comparing standard and maternal age dependent recruitment two decades into the future suggest that the inclusion of maternal age in recruitment models has little effect on projected biomasses. However, this similarity in biomass trajectory masked an increased sensitivity of populations with maternal age-dependent recruitment to stock age-structure. In particular, simulations with maternal age-dependent recruitment responded strongly to changes in fishing mortality on the oldest age classes, while simulations using standard recruitment models did not. Populations with maternal age-dependent recruitment can exhibit increased biomass catch even if fishing mortality on older individuals was reduced. Overall, simulations suggested that the influence of maternal age on population dynamics are more nuanced than suggested by previous research and indicate that careful consideration of the effects of age-structure on populations may lead to substantially different fisheries management reference points-particularly with respect to age-specific fishing mortality-than classical models. While these results suggest a link between maternal age and population productivity, future research requires the incorporation of biologically reasonable and empirically defensible mechanisms to clarify the effect of age on population dynamics. DOI
37. Tamburello, N; Côté, IM; Dulvy, NK. (2015) Energy and the Scaling of Animal Space Use.American Naturalist 186: 196-211 Energy and the Scaling of Animal Space Use
allometry; home range; metabolic theory; prey handling; prey size; spatial ecology
Daily animal movements are usually limited to a discrete home range area that scales allometrically with body size, suggesting that home-range size is shaped by metabolic rates and energy availability across species. However, there is little understanding of the relative importance of the various mechanisms proposed to influence home-range scaling (e.g., differences in realm productivity, thermoregulation, locomotion strategy, dimensionality, trophic guild, and prey size) and whether these extend beyond the commonly studied birds and mammals. We derive new home-range scaling relationships for fishes and reptiles and use a model-selection approach to evaluate the generality of home-range scaling mechanisms across 569 vertebrate species. We find no evidence that home-range allometry varies consistently between aquatic and terrestrial realms or thermoregulation strategies, but we find that locomotion strategy, foraging dimension, trophic guild, and prey size together explain 80% of the variation in home-range size across vertebrates when controlling for phylogeny and tracking method. Within carnivores, smaller relative prey size among gape-limited fishes contributes to shallower scaling relative to other predators. Our study reveals how simple morphological traits and prey-handling ability can profoundly influence individual space use, which underpins broader-scale patterns in the spatial ecology of vertebrates. DOI
36. Trebilco, R; Dulvy, NK; Stewart, H; Salomon, AK. (2015) The role of habitat complexity in shaping the size structure of a temperate reef fish community.Marine Ecology Progress Series 532: 197-211 The role of habitat complexity in shaping the size structure of a temperate reef fish community
Biomass size spectra; Community ecology; Coral reef; Ecosystem baseline; Energy flow; Foundation species
Understanding how habitat complexity shapes fish communities is necessary to predict the consequences of future habitat change. On temperate rocky reefs, the presence and characteristics of canopy-forming kelps and the architectural complexity, or rugosity, of the underlying rocky substratum are foundational elements of habitat complexity. However, it is not yet clear how these factors shape the size structure of rocky-reef-associated fish communities. Here, we use biomass spectrum models to evaluate how fish community size structure in high-latitude rocky-reef kelp forests is shaped by substratum rugosity and the degree of closure and density of the kelp canopy. We found that the presence of a closed kelp canopy was associated with an average 75% increase in overall fish biomass compared to open-canopy reefs. Furthermore, on the highest-rugosity reefs, the biomass of small fishes (32-64 g) was 800% higher than on the lowest-rugosity reefs, while large fish (1-2 kg) biomass was 60% lower. Consequently, biomass was more evenly distributed across body-size classes on high-rugosity reefs. By decomposing the biomass spectrum into total biomass and mean individual body mass, we found that higher kelp stipe densities also tended to be associated with larger fishes, but this effect was outweighed by the tendency for more small-bodied fishes with increasing rugosity. This study demonstrates how size-based analyses can give new insights into the ecology of temperate reef communities, and may be useful for tracking changes in kelp-associated assemblages in the coming decades with the maturation of marine protected areas, the recovery of sea otter populations, and changing climate. DOI
35. Bates, AE; Pecl, GT; Frusher, S; Hobday, AJ; Wernberg, T; Smale, DA; Sunday, JM; Hill, NA; Dulvy, NK; Colwell, RK; Holbrook, NJ; Fulton, EA; Slawinski, D; Feng, M; Edgar, GJ; Radford, BT; Thompson, PA; Watson, RA. (2014) Defining and observing stages of climate-mediated range shifts in marine systems.Global Environmental Change-Human and Policy Dimensions 26: 27-38 Defining and observing stages of climate-mediated range shifts in marine systems
Species redistribution; Attribution; Prediction; Biogeography; Warming; Abundance-occupancy relationship
Climate change is transforming the structure of biological communities through the geographic extension and contraction of species' ranges. Range edges are naturally dynamic, and shifts in the location of range edges occur at different rates and are driven by different mechanisms. This leads to challenges when seeking to generalize responses among taxa and across systems. We focus on warming-related range shifts in marine systems to describe extensions and contractions as stages. Range extensions occur as a sequence of (1) arrival, (2) population increase, and (3) persistence. By contrast, range contractions occur progressively as (1) performance decline, (2) population decrease and (3) local extinction. This stage-based framework can be broadly applied to geographic shifts in any species, life-history stage, or population subset. Ideally the probability of transitioning through progressive range shift stages could be estimated from empirical understanding of the various factors influencing range shift rates. Nevertheless, abundance and occupancy data at the spatial resolution required to quantify range shifts are often unavailable and we suggest the pragmatic solution of considering observations of range shifts within a confidence framework incorporating the type, amount and quality of data. We use case studies to illustrate how diverse evidence sources can be used to stage range extensions and contractions and assign confidence that an observed range shift stage has been reached. We then evaluate the utility of trait-based risk (invasion) and vulnerability (extinction) frameworks for application in a range shift context and find inadequacies, indicating an important area for development. We further consider factors that influence rates of extension and contraction of range edges in marine habitats. Finally, we suggest approaches required to increase our capacity to observe and predict geographic range shifts under climate change. (C) 2014 Elsevier Ltd. All rights reserved. DOI
34.Dulvy, NK; Fowler, SL; Musick, JA; Cavanagh, RD; Kyne, PM; Harrison, LR; Carlson, JK; Davidson, LNK; Fordham, SV; Francis, MP; Pollock, CM; Simpfendorfer, CA; Burgess, GH; Carpenter, KE; Compagno, LJV; Ebert, DA; Gibson, C; Heupel, MR; Livingstone, SR; Sanciangco, JC; Stevens, JD; Valenti, S; White, WT. (2014) Extinction risk and conservation of the world's sharks and rays.Elife 3 Extinction risk and conservation of the world's sharks and rays
The rapid expansion of human activities threatens ocean-wide biodiversity. Numerous marine animal populations have declined, yet it remains unclear whether these trends are symptomatic of a chronic accumulation of global marine extinction risk. We present the first systematic analysis of threat for a globally distributed lineage of 1,041 chondrichthyan fishes-sharks, rays, and chimaeras. We estimate that one-quarter are threatened according to IUCN Red List criteria due to overfishing (targeted and incidental). Large-bodied, shallow-water species are at greatest risk and five out of the seven most threatened families are rays. Overall chondrichthyan extinction risk is substantially higher than for most other vertebrates, and only one-third of species are considered safe. Population depletion has occurred throughout the world's ice-free waters, but is particularly prevalent in the Indo-Pacific Biodiversity Triangle and Mediterranean Sea. Improved management of fisheries and trade is urgently needed to avoid extinctions and promote population recovery. DOI
33. Green, SJ; Dulvy, NK; Brooks, AML; Akins, JL; Cooper, AB; Miller, S; Côté, IM. (2014) Linking removal targets to the ecological effects of invaders: a predictive model and field test.Ecological Applications 24: 1311-1322 Linking removal targets to the ecological effects of invaders: a predictive model and field test
ecological model; eradication; exotic species; lionfish; marine management; metabolic scaling theory; population control; predation; productivity; Pterois miles; Pterois volitans; size-based analysis
Species invasions have a range of negative effects on recipient ecosystems, and many occur at a scale and magnitude that preclude complete eradication. When complete extirpation is unlikely with available management resources, an effective strategy may be to suppress invasive populations below levels predicted to cause undesirable ecological change. We illustrated this approach by developing and testing targets for the control of invasive Indo-Pacific lionfish (Pterois volitans and P. miles) on Western Atlantic coral reefs. We first developed a size-structured simulation model of predation by lionfish on native fish communities, which we used to predict threshold densities of lionfish beyond which native fish biomass should decline. We then tested our predictions by experimentally manipulating lionfish densities above or below reef-specific thresholds, and monitoring the consequences for native fish populations on 24 Bahamian patch reefs over 18 months. We found that reducing lionfish below predicted threshold densities effectively protected native fish community biomass from predation-induced declines. Reductions in density of 25-92%, depending on the reef, were required to suppress lionfish below levels predicted to overconsume prey. On reefs where lionfish were kept below threshold densities, native prey fish biomass increased by 50-70%. Gains in small (<6 cm) size classes of native fishes translated into lagged increases in larger size classes over time. The biomass of larger individuals (>15 cm total length), including ecologically important grazers and economically important fisheries species, had increased by 10-65% by the end of the experiment. Crucially, similar gains in prey fish biomass were realized on reefs subjected to partial and full removal of lionfish, but partial removals took 30% less time to implement. By contrast, the biomass of small native fishes declined by >50% on all reefs with lionfish densities exceeding reef-specific thresholds. Large inter-reef variation in the biomass of prey fishes at the outset of the study, which influences the threshold density of lionfish, means that we could not identify a single rule of thumb for guiding control efforts. However, our model provides a method for setting reef-specific targets for population control using local monitoring data. Our work is the first to demonstrate that for ongoing invasions, suppressing invaders below densities that cause environmental harm can have a similar effect, in terms of protecting the native ecosystem on a local scale, to achieving complete eradication. DOI PubMed
32. Heupel, MR; Knip, DM; Simpfendorfer, CA; Dulvy, NK. (2014) Sizing up the ecological role of sharks as predators.Marine Ecology Progress Series 495: 291-298 Sizing up the ecological role of sharks as predators
Top-down control; Predator-prey interactions; Predation risk; Home range; Ecology of fear
The decline of predators in a variety of ecosystems has transformed community structure through mesopredator release and trophic cascades. Elasmobranch fishes, one of the earth's most ubiquitous and diverse clade of predatory species, provide a model group for defining marine predator roles. We consider whether the ecological predatory role of sharks is adequately defined by terrestrial-derived notions of apex-and mesopredation. Indeterminate growth and ontogenetic diet shifts may mean species-level classification of predatory roles is inadequate. We propose that examining the trophic level and body size of species might be the most pragmatic and informative way to define the ecological roles of predators. DOI
31. Anderson, SC; Cooper, AB; Dulvy, NK. (2013) Ecological prophets: quantifying metapopulation portfolio effects.Methods in Ecology and Evolution 4: 971-981 Ecological prophets: quantifying metapopulation portfolio effects
TAYLORS POWER-LAW; DIVERSITY-STABILITY RELATIONSHIPS; STATISTICAL INEVITABILITY; TEMPORAL STABILITY; FISH POPULATIONS; TIME-SERIES; BIODIVERSITY; VARIABILITY; DYNAMICS; PRODUCTIVITY
1. A financial portfolio metaphor is often used to describe how population diversity can increase temporal stability of a group of populations. The portfolio effect (PE) refers to the stabilizing effect from a population acting as a group or portfolio' of diverse subpopulations instead of a single homogeneous population or asset'. A widely used measure of the PE (the average-CV PE) implicitly assumes that the slope (z) of a log-log plot of mean temporal abundance and variance (Taylor's power law) equals two. 2. Existing theory suggests an additional unexplored empirical PE that accounts for z, the mean-variance PE. We use a theoretical and empirical approach to explore the strength and drivers of the PE for metapopulations when we account for Taylor's power law compared with when we do not. Our empirical comparison uses data from 51 metapopulations and 1070 subpopulations across salmon, moths and reef fishes. 3. Ignoring Taylor's power law may overestimate the stabilizing effect of population diversity for metapopulations. The disparity between the metrics is greatest at low z values where the average-CV PE indicates a strong PE. Compared with the mean-variance method, the average-CV PE estimated a stronger PE in 84% of metapopulations by up to sevenfold. The divergence between the methods was strongest for reef fishes (1.0 < z < 1.7) followed by moths (1.5 < z < 1.9). The PEs were comparable for salmon where z approximate to 2. 4. We outline practical recommendations for estimating ecological PEs based on research questions, study systems and available data. Because most PEs were stabilizing and diversity can be slow to restore, our meta-analysis of metapopulations suggests that the safest management approach is to conserve biological complexity. DOI
29. Hocking, MD; Dulvy, NK; Reynolds, JD; Ring, RA; Reimchen, TE. (2013) Salmon subsidize an escape from a size spectrum.Proceedings of the Royal Society B-Biological Sciences 280 Salmon subsidize an escape from a size spectrum
SPECIES ABUNDANCE DISTRIBUTIONS; BODY MASS RELATIONSHIPS; STRUCTURED FOOD WEBS; PACIFIC SALMON; POPULATION-DENSITY; ENERGY USE; COMMUNITIES; ECOSYSTEMS; PREDATION; NUTRIENTS
A general rule in ecology is that the abundance of species or individuals in communities sharing a common energy source decreases with increasing body size. However, external energy inputs in the form of resource subsidies can modify this size spectrum relationship. Here, we provide the first test of how a marine resource subsidy can affect size spectra of terrestrial communities, based on energy derived from Pacific salmon carcasses affecting a forest soil community beside streams in western Canada. Using both species-based and individual approaches, we found size structuring in this forest soil community, and transient community-wide doubling of standing biomass in response to energy pulses from Pacific salmon carcasses. One group of species were clear outliers in the middle of the size spectrum relationship: larval calliphorid and dryomyzid flies, which specialize on salmon carcasses, and which showed a tenfold increase in biomass in their size class when salmon were available. Thus, salmon subsidize their escape from the size spectrum. These results suggest that using a size-based perspective of resource subsidies can provide new insights into the structure and functioning of food webs. DOI
28. Juan-Jorda, MJ; Mosqueira, I; Freire, J; Dulvy, NK. (2013) The Conservation and Management of Tunas and Their Relatives: Setting Life History Research Priorities.PLOS One 8 The Conservation and Management of Tunas and Their Relatives: Setting Life History Research Priorities
MACKEREL SCOMBER-JAPONICUS; SOUTHERN BLUEFIN TUNA; EXTINCTION RISK; MARINE FISHES; INTRASPECIFIC VARIATION; REPRODUCTIVE-BIOLOGY; THUNNUS-ORIENTALIS; AGE-DETERMINATION; GROWTH; WATERS
Scombrids (tunas, bonitos, Spanish mackerels and mackerels) support important fisheries in tropical, subtropical and temperate waters around the world, being one of the most economically- and socially-important marine species globally. Their sustainable exploitation, management and conservation depend on accurate life history information for the development of quantitative fisheries stock assessments, and in the fishery data-poor situations for the identification of vulnerable species. Here, we assemble life history traits (maximum size, growth, longevity, maturity, fecundity, spawning duration and spawning interval) for the 51 species of scombrids globally. We identify major biological gaps in knowledge and prioritize life history research needs in scombrids based on their biological gaps in knowledge, the importance of their fisheries and their current conservation status according to the International Union for Conservation of Nature Red List. We find that the growth and reproductive biology of tunas and mackerel species have been more extensively studied than for Spanish mackerels and bonitos, although there are notable exceptions in all groups. We also reveal that reproductive biology of species, particular fecundity, is the least studied biological aspect in scombrids. We identify two priority groups, including 32 species of scombrids, and several populations of principal market tunas, for which life history research should be prioritized following the species-specific life history gaps identified in this study in the coming decades. By highlighting the important gaps in biological knowledge and providing a priority setting for life history research in scombrid species this study provides guidance for management and conservation and serves as a guide for biologists and resource managers interested in the biology, ecology, and management of scombrid species. DOI
27. Pardo, SA; Cooper, AB; Dulvy, NK. (2013) Avoiding fishy growth curves.Methods in Ecology and Evolution 4: 353-360 Avoiding fishy growth curves
GULF-OF-MEXICO; LIFE-HISTORY; BIOLOGICAL PARAMETERS; MULTIMODEL INFERENCE; HAMMERHEAD SHARK; GEAR SELECTIVITY; ATLANTIC-OCEAN; AGE; MODEL; SIZE
Somatic growth is a fundamental property of living organisms, and is of particular importance for species with indeterminate growth that can change in size continuously throughout their life. For example, fishes can increase in size by 26 orders of magnitude during their lifetime, resulting in changes in production, consumption and function at the ecosystem scale. Within species, growth rates are traded off against other life-history parameters, hence an accurate description of growth is essential to understand the comparative demography, productivity, fisheries yield and extinction risk of populations and species. The growth trajectory of indeterminate growing sharks and rays (elasmobranchs) and bony fishes (teleosts) is usually modelled using a three-parameter logarithmic function, the von Bertalanffy growth function (VBGF), to describe the total length of the average individual at any given age. Recently, however, a two-parameter form has gained popularity. Rather than being estimated in the model fitting process, the third y-intercept parameter (L0) of the VBGF has been interpreted as being biologically equivalent to, and thus fixed as, the empirically estimated size at birth. We tested the equivalence assumption that L0 is the same or similar to size at birth by comparing empirical estimates of size at birth available from the literature with estimates of L0 from published data from elasmobranchs, and found that even though there is an overlap of values, there is a high degree of variability between them. We calculate the bias in the growth coefficient (k) of the VBGF by comparison between the two- and three-parameter estimation methods. We show that slight deviations in fixed L0 can cause considerable bias in growth estimates in the two-parameter VBGF while providing no benefit even when L0 matches the true value. We show that the effect of this biased growth estimate has profound consequences for fisheries stock status. We strongly recommend the use of the three-parameter VBGF and discourage use of the two-parameter VBGF because it results in substantially biased growth estimates even with slight variations in the value of fixed L0. DOI
26. Blanchard, JL; Jennings, S; Holmes, R; Harle, J; Merino, G; Allen, JI; Holt, J; Dulvy, NK; Barange, M. (2012) Potential consequences of climate change for primary production and fish production in large marine ecosystems.Philosophical Transactions of the Royal Society B-Biological Sciences 367: 2979-2989 Potential consequences of climate change for primary production and fish production in large marine ecosystems
global environmental change; benthic-pelagic coupling; fisheries ecology; marine macroecology; marine communities; size spectrum
Existing methods to predict the effects of climate change on the biomass and production of marine communities are predicated on modelling the interactions and dynamics of individual species, a very challenging approach when interactions and distributions are changing and little is known about the ecological mechanisms driving the responses of many species. An informative parallel approach is to develop size-based methods. These capture the properties of food webs that describe energy flux and production at a particular size, independent of species' ecology. We couple a physical-biogeochemical model with a dynamic, size-based food web model to predict the future effects of climate change on fish biomass and production in 11 large regional shelf seas, with and without fishing effects. Changes in potential fish production are shown to most strongly mirror changes in phytoplankton production. We project declines of 30-60% in potential fish production across some important areas of tropical shelf and upwelling seas, most notably in the eastern Indo-Pacific, the northern Humboldt and the North Canary Current. Conversely, in some areas of the high latitude shelf seas, the production of pelagic predators was projected to increase by 28-89%. DOI
25. Chin A, White J, Dulvy NK. (2012) Aquatic conservation: Environment in Queensland at risk.Nature 490: 176. Aquatic conservation: Environment in Queensland at risk
In the state of Queensland, Australia, hard-won environmental protections are under threat.
In April this year, Queensland elected a new government that is pro-development and pro-mining. These activities have been burgeoning over the past few years, prompting the United Nations Educational, Scientific and Cultural Organization (UNESCO) to investigate whether the Great… DOI
24. Juan-Jordá, M.J., Mosqueira, I., Freire, J. & Dulvy, N.K. (2012) Life in 3-D: life history strategies in tunas, mackerels and bonitos.Reviews in Fish Biology and FisheriesLife in 3-D: life history strategies in tunas, mackerels and bonitos
Sexual dimorphism
Life history trade-offs
Mortality
Data-poor species
Data-poor methods
Conservation
Mammals
Life history data set
The scombrids (tunas, bonitos, Spanish mackerels and mackerels) sustain some of the most important fisheries in the world and their sustainable management depends on better understanding of their life history strategies. Here, we first assemble life history information on maximum size, growth, longevity, maturity, fecundity and spawning duration and interval for all scombrid species. Second we characterize their life history patterns and trait co-variation and evaluate how many principal axes of trait variation underlie scombrid life history strategies. Most of their life history variation can be explained along three axes or dimensions: size, speed, and reproductive schedule. Body size governs the first axis ranking species along a small-large continuum. The second axis was mostly influenced by time-related traits, such as longevity, growth rates, spawning duration, time between spawning events, ranking species along a slow-fast continuum of life histories. Scombrid species with the slowest life histories such as Atlantic bluefin tuna Thunnus thynnus and Atlantic mackerel Scomber scombrus tend to inhabit more temperate waters while species with faster life histories such as yellowfin tuna Thunnus albacares and short mackerel Rastrelliger brachysoma are typically found in more tropical waters. The third axis comprises the negative relationship between number of eggs produced at length of maturity and rate in gain of fecundity with size describing the schedule of reproductive allocation which reflects a fundamental trade-off between reproduction and growth. Finally, in addition we show that the life history strategies of scombrids conform more closely to the Periodic and Opportunistic strategists within the triangular model of fish life histories. DOI
23. Keith, SA; Webb, TJ; Bohning-Gaese, K; Connolly, SR; Dulvy, NK; Eigenbrod, F; Jones, KE; Price, T; Redding, DW; Owens, IPF; Isaac, NJB. (2012) What is macroecology?Biology Letters 8: 904-906 What is macroecology?
macroecology; spatial scale; process-based model; theory; ecosystem; disease
The symposium 'What is Macroecology?' was held in London on 20 June 2012. The event was the inaugural meeting of the Macroecology Special Interest Group of the British Ecological Society and was attended by nearly 100 scientists from 11 countries. The meeting reviewed the recent development of the macroecological agenda. The key themes that emerged were a shift towards more explicit modelling of ecological processes, a growing synthesis across systems and scales, and new opportunities to apply macroecological concepts in other research fields. DOI
22. McClenachan, L; Cooper, AB; Carpenter, KE; Dulvy, NK. (2012) Extinction risk and bottlenecks in the conservation of charismatic marine species.Conservation Letters 5: 73-80 Extinction risk and bottlenecks in the conservation of charismatic marine species
CITES; climate change; elasmobranchs; fishing impacts; IUCN Red List; reef fish; taxonomic bias
The oceans face a biodiversity crisis, but the degree and scale of extinction risk remains poorly characterized. Charismatic species are most likely to garner greatest support for conservation and thus provide a best-case scenario of the status of marine biodiversity. We summarize extinction risk and diagnose impediments to successful conservation for 1,568 species in 16 families of marine animals in the movie Finding Nemo. Sixteen percent (1234%) of those that have been evaluated are threatened, ranging from 9% (728%) of bony fishes to 100% (83100%) of marine turtles. A lack of scientific knowledge impedes analysis of threat status for invertebrates, which have 1,000 times fewer conservation papers than do turtles. Legal protection is severely deficient for sharks and rays; only 8% of threatened species in our analysis are protected. Extinction risk among wide-ranging taxa is higher than most terrestrial groups, suggesting a different conservation focus is required in the sea. DOI
21. Merino, G; Barange, M; Blanchard, JL; Harle, J; Holmes, R; Allen, I; Allison, EH; Badjeck, MC; Dulvy, NK; Holt, J; Jennings, S; Mullon, C; Rodwell, LD. (2012) Can marine fisheries and aquaculture meet fish demand from a growing human population in a changing climate?Global Environmental Change-Human and Policy Dimensions 22: 795-806 Can marine fisheries and aquaculture meet fish demand from a growing human population in a changing climate?
Global environmental change; Fish production; Fisheries; Aquaculture; Adaptation
Expansion in the world's human population and economic development will increase future demand for fish products. As global fisheries yield is constrained by ecosystems productivity and management effectiveness, per capita fish consumption can only be maintained or increased if aquaculture makes an increasing contribution to the volume and stability of global fish supplies. Here, we use predictions of changes in global and regional climate (according to IPCC emissions scenario A1B), marine ecosystem and fisheries production estimates from high resolution regional models, human population size estimates from United Nations prospects, fishmeal and oil price estimations, and projections of the technological development in aquaculture feed technology, to investigate the feasibility of sustaining current and increased per capita fish consumption rates in 2050. We conclude that meeting current and larger consumption rates is feasible, despite a growing population and the impacts of climate change on potential fisheries production, but only if fish resources are managed sustainably and the animal feeds industry reduces its reliance on wild fish. Ineffective fisheries management and rising fishmeal prices driven by greater demand could, however, compromise future aquaculture production and the availability of fish products. (C) 2012 Elsevier Ltd. All rights reserved. DOI
20. Porszt, EJ; Peterman, RM; Dulvy, NK; Cooper, AB; Irvine, JR. (2012) Reliability of Indicators of Decline in Abundance.Conservation Biology 26: 894-904 Reliability of Indicators of Decline in Abundance
COSEWIC; IUCN; receiver operating characteristic (ROC); sockeye salmon; threat indicators; caracteristica de operacion del receptor; COR; COSEWIC; indicadores de amenaza; IUCN; Oncorhynchus nerka
Although there are many indicators of endangerment (i.e., whether populations or species meet criteria that justify conservation action), their reliability has rarely been tested. Such indicators may fail to identify that a population or species meets criteria for conservation action (false negative) or may incorrectly show that such criteria have been met (false positive). To quantify the rate of both types of error for 20 commonly used indicators of declining abundance (threat indicators), we used receiver operating characteristic curves derived from historical (19382007) data for 18 sockeye salmon (Oncorhynchus nerka) populations in the Fraser River, British Columbia, Canada. We retrospectively determined each population's yearly status (reflected by change in abundance over time) on the basis of each indicator. We then compared that population's status in a given year with the status in subsequent years (determined by the magnitude of decline in abundance across those years). For each sockeye population, we calculated how often each indicator of past status matched subsequent status. No single threat indicator provided error-free estimates of status, but indicators that reflected the extent (i.e., magnitude) of past decline in abundance (through comparison of current abundance with some historical baseline abundance) tended to better reflect status in subsequent years than the rate of decline over the previous 3 generations (a widely used indicator). We recommend that when possible, the reliability of various threat indicators be evaluated with empirical analyses before such indicators are used to determine the need for conservation action. These indicators should include estimates from the entire data set to take into account a historical baseline. DOI
19. Sunday, JM; Bates, AE; Dulvy, NK. (2012) Thermal tolerance and the global redistribution of animals.Nature Climate Change 2: 686-690 Thermal tolerance and the global redistribution of animals
The redistribution of life on Earth has emerged as one of the most significant biological responses to anthropogenic climate warming(1-3). Despite being one of the most long-standing puzzles in ecology(4), we still have little understanding of how temperature sets geographic range boundaries(5). Here we show that marine and terrestrial ectotherms differ in the degree to which they fill their potential latitudinal ranges, as predicted from their thermal tolerance limits. Marine ectotherms more fully occupy the extent of latitudes tolerable within their thermal tolerance limits, and are consequently predicted to expand at their poleward range boundaries and contract at their equatorward boundaries with climate warming. In contrast, terrestrial ectotherms are excluded from the warmest regions of their latitudinal range; thus, the equatorward, or 'trailing' range boundaries, may not shift consistently towards the poles with climate warming. Using global observations of climate-induced range shifts, we test this prediction and show that in the ocean, shifts at both range boundaries have been equally responsive, whereas on land, equatorward range boundaries have lagged in response to climate warming. These results indicate that marine species' ranges conform more closely to their limits of thermal tolerance, and thus range shifts will be more predictable and coherent. However, on land, warmer range boundaries are not at equilibrium with heat tolerance. Understanding the relative contribution of factors other than temperature in controlling equatorward range limits is critical for predicting distribution changes, with implications for population and community viability. DOI
17. Alvarez-Filip L., Gill J.A., Dulvy N.K. (2011) Complex reef architecture supports more small-bodied fishes and longer food chains on Caribbean reefs.Ecosphere 2, art118 Complex reef architecture supports more small-bodied fishes and longer food chains on Caribbean reefs
Coral community shifts towards reefs dominated by stress-resistant corals have contributed to rapid declines in the architectural complexity of reefs throughout the Caribbean. Complex reef architecture provides important niches and refuges for many reef fishes and thus widespread declines in reef complexity could have important consequences for the structure and function of fish assemblages. We explore the influence of reef architecture on fish assemblages by comparing the size and trophic structure of reef fishes along a 20 km-long 15-reef gradient of coral cover, coral species dominance and architectural complexity in Cozumel, Mexico. Our results show that reefs with high architectural complexity, in particular those dominated by robust Montastraea corals, supported fish assemblages with larger numbers of individuals in the smallest size classes (<20 cm) and longer food chains (higher mean trophic levels). The association between coral complexity and fish communities is highly size-structured and is greatest for smallest size classes. The greater abundance of both small fish and the key early life stages of larger fishes on more complex reefs suggests that architectural complexity may influence entire reef fish assemblages, even though larger fish are less dependent on reef complexity. Key reef-building corals such as Montastraea are thus likely to be disproportionately important for maintaining reef fish communities, and shifts in Caribbean coral communities may compromise fish recruitment and truncate food chains, reducing resilience and inhibiting reef recovery from degradation.PDF DOI
16. Alvarez-Filip, L; Côté, IM; Gill, JA; Watkinson, AR; Dulvy, NK. (2011) Region-wide temporal and spatial variation in Caribbean reef architecture: is coral cover the whole story?Global Change Biology 17: 2470-2477 Region-wide temporal and spatial variation in Caribbean reef architecture: is coral cover the whole story?
climate change; ecosystem services; foundation species; habitat loss; reef degradation
The architectural complexity of coral reefs is largely generated by reef-building corals, yet the effects of current regional-scale declines in coral cover on reef complexity are poorly understood. In particular, both the extent to which declines in coral cover lead to declines in complexity and the length of time it takes for reefs to collapse following coral mortality are unknown. Here we assess the extent of temporal and spatial covariation between coral cover and reef architectural complexity using a Caribbean-wide dataset of temporally replicated estimates spanning four decades. Both coral cover and architectural complexity have declined rapidly over time, with little evidence of a time-lag. However, annual rates of change in coral cover and complexity do not covary, and levels of complexity vary greatly among reefs with similar coral cover. These findings suggest that the stressors influencing Caribbean reefs are sufficiently severe and widespread to produce similar regional-scale declines in coral cover and reef complexity, even though reef architectural complexity is not a direct function of coral cover at local scales. Given that architectural complexity is not a simple function of coral cover, it is important that conservation monitoring and restoration give due consideration to both architecture and coral cover. This will help ensure that the ecosystem services supported by architectural complexity, such as nutrient recycling, dissipation of wave energy, fish production and diversity, are maintained and enhanced. DOI
15. Alvarez-Filip, L; Dulvy, NK; Côté, IM; Watkinson, AR; Gill, JA. (2011) Coral identity underpins architectural complexity on Caribbean reefs.Ecological Applications 21: 2223-2231 Coral identity underpins architectural complexity on Caribbean reefs
biodiversity; coral; Cozumel; Mexico; dominance; functional groups; habitat complexity; landscape ecology; reef
The architectural complexity of ecosystems can greatly influence their capacity to support biodiversity and deliver ecosystem services. Understanding the components underlying this complexity can aid the development of effective strategies for ecosystem conservation. Caribbean coral reefs support and protect millions of livelihoods, but recent anthropogenic change is shifting communities toward reefs dominated by stress-resistant coral species, which are often less architecturally complex. With the regionwide decline in reef fish abundance, it is becoming increasingly important to understand changes in coral reef community structure and function. We quantify the influence of coral composition, diversity, and morpho-functional traits on the architectural complexity of reefs across 91 sites at Cozumel, Mexico. Although reef architectural complexity increases with coral cover and species richness, it is highest on sites that are low in taxonomic evenness and dominated by morpho-functionally important, reef-building coral genera, particularly Montastraea. Sites with similar coral community composition also tend to occur on reefs with very similar architectural complexity, suggesting that reef structure tends to be determined by the same key species across sites. Our findings provide support for prioritizing and protecting particular reef types, especially those dominated by key reef-building corals, in order to enhance reef complexity. DOI
14. Chassot, E; Bonhommeau, S; Reygondeau, G; Nieto, K; Polovina, JJ; Huret, M; Dulvy, NK; Demarcq, H. (2011) Satellite remote sensing for an ecosystem approach to fisheries management.ICES Journal of Marine Science 68 Satellite remote sensing for an ecosystem approach to fisheries management
ecosystem approach; fisheries; mesoscale; satellite; tracking
Satellite remote sensing (SRS) of the marine environment has become instrumental in ecology for environmental monitoring and impact assessment, and it is a promising tool for conservation issues. In the context of an ecosystem approach to fisheries management (EAFM), global, daily, systematic, high-resolution images obtained from satellites provide a good data source for incorporating habitat considerations into marine fish population dynamics. An overview of the most common SRS datasets available to fishery scientists and state-of-the-art data-processing methods is presented, focusing on recently developed techniques for detecting mesoscale features such as eddies, fronts, filaments, and river plumes of major importance in productivity enhancement and associated fish aggregation. A comprehensive review of remotely sensed data applications in fisheries over the past three decades for investigating the relationships between oceanographic conditions and marine resources is provided, emphasizing how synoptic and information-rich SRS data have become instrumental in ecological analyses at community and ecosystem scales. Finally, SRS data, in conjunction with automated in situ data-acquisition systems, can provide the scientific community with a major source of information for ecosystem modelling, a key tool for implementing an EAFM. DOI
13. Juan-Jorda, MJ; Mosqueira, I; Cooper, AB; Freire, J; Dulvy, NK. (2011) Global population trajectories of tunas and their relatives.Proceedings of the National Academy of Sciences of the United States of America 108: 20650-20655 Global population trajectories of tunas and their relatives
Tunas and their relatives dominate the world's largest ecosystems and sustain some of the most valuable fisheries. The impacts of fishing on these species have been debated intensively over the past decade, giving rise to divergent views on the scale and extent of the impacts of fisheries on pelagic ecosystems. We use all available age-structured stock assessments to evaluate the adult biomass trajectories and exploitation status of 26 populations of tunas and their relatives (17 tunas, 5 mackerels, and 4 Spanish mackerels) from 1954 to 2006. Overall, populations have declined, on average, by 60% over the past half century, but the decline in the total adult biomass is lower (52%), driven by a few abundant populations. The trajectories of individual populations depend on the interaction between life histories, ecology, and fishing pressure. The steepest declines are exhibited by two distinct groups: the largest, longest lived, highest value temperate tunas and the smaller, short-lived mackerels, both with most of their populations being overexploited. The remaining populations, mostly tropical tunas, have been fished down to approximately maximum sustainable yield levels, preventing further expansion of catches in these fisheries. Fishing mortality has increased steadily to the point where around 12.5% of the tunas and their relatives are caught each year globally. Overcapacity of these fisheries is jeopardizing their long-term sustainability. To guarantee higher catches, stabilize profits, and reduce collateral impacts on marine ecosystems requires the rebuilding of overexploited populations and stricter management measures to reduce overcapacity and regulate threatening trade. DOI
12. Mull, CG; Yopak, KE; Dulvy, NK. (2011) Does more maternal investment mean a larger brain? Evolutionary relationships between reproductive mode and brain size in chondrichthyans.Marine and Freshwater Research 62: 567-575 Does more maternal investment mean a larger brain? Evolutionary relationships between reproductive mode and brain size in chondrichthyans
allometry; encephalisation; pGLS; relative brain size; reproductive mode
Chondrichthyans have the most diverse array of reproductive strategies of any vertebrate group, ranging from egg-laying to live-bearing with placental matrotrophy. Matrotrophy is defined as additional maternal provisioning beyond the yolk to the developing neonate; in chondrichthyans, this occurs through a range of mechanisms including uterine milk, oophagy, uterine cannibalism and placentotrophy. Chondrichthyans also exhibit a wide range of relative brain sizes and highly diverse patterns of brain organisation. Brains are energetically expensive to produce and maintain, and represent a major energetic constraint during early life in vertebrates. In mammals, more direct maternal-fetal placental connections have been associated with larger brains (steeper brain-body allometric scaling relationships). We test for a relationship between reproductive mode and relative brain size across 85 species from six major orders of chondrichthyans by using several phylogenetic comparative analyses. Ordinary least-squares (OLS) and reduced major axis (RMA) regression of body mass versus brain mass suggest that increased maternal investment results in a larger relative brain size. Our findings were supported by phylogenetic generalised least-squares models (pGLS), which also highlighted that these results vary with evolutionary tempo, as described by different branch-length assumptions. Across all analyses, maximum body size had a significant influence on the relative brain size, with large-bodied species (body mass > 100 kg) having relatively smaller brains. The present study suggests that there may be a link between reproductive investment and relative brain size in chondrichthyans; however, a more definitive test requires a better-resolved phylogeny and a more nuanced categorisation of the level of maternal investment in chondrichthyans. DOI
11. Salomon, AK; Gaichas, SK; Jensen, OP; Agostini, VN; Sloan, NA; Rice, J; McClanahan, TR; Ruckelshaus, MH; Levin, PS; Dulvy, NK; Babcock, EA. (2011) BRIDGING THE DIVIDE BETWEEN FISHERIES AND MARINE CONSERVATION SCIENCE.Bulletin of Marine Science 87: 251-274 BRIDGING THE DIVIDE BETWEEN FISHERIES AND MARINE CONSERVATION SCIENCE
Researchers from traditionally disparate disciplines and practitioners with typically incongruent mandates have begun working together to better understand and solve marine conservation and sustainable yield problems. Conservation practitioners are recognizing the need to achieve conservation goals in seascapes that are a source of livelihood and food security, while fisheries management is realizing that achieving economically and ecologically sustainable fisheries requires an understanding of the role of biodiversity and ecosystem dynamics in fishery production. Yet, tensions still exist due to the unique histories, epistemologies, cultures, values, and quantitative techniques of fisheries and marine conservation science, and the often-divergent objectives of the institutions and organizations these academic disciplines inform. While there is general agreement on what needs to be achieved (less overfishing, recovery of depleted fish stocks, reduction in bycatch and habitat impacts, jobs, food production), specific objectives and how best to achieve them remain contentious and unresolved. By analyzing three contemporary yet controversial marine policies (ecosystem-based fishery management, marine protected areas, and catch shares) and specific case studies, we demonstrate how both fisheries and marine conservation science can be used to provide clear scientific advice to practitioners and provide empirical evidence of the benefits of bridging the disciplinary divide. Finally, we discuss future prospects for collaboration in an emerging issue at the nexus of conservation and fishery management: eco-certification. Drawing on lessons learned from these empirical examples, we outline general processes necessary for clearly defining multiple conservation and fisheries objectives in working seascapes. By bridging the divide, we illuminate the process of navigating trade-offs between multiple objectives in a finite world. DOI
10. Simpfendorfer, CA; Heupel, MR; White, WT; Dulvy, NK. (2011) The importance of research and public opinion to conservation management of sharks and rays: a synthesis.Marine and Freshwater Research 62: 518-527 The importance of research and public opinion to conservation management of sharks and rays: a synthesis
chondrichthyes; research priorities; sustainable use
Growing concern for the world's shark and ray populations is driving the need for greater research to inform conservation management. A change in public perception, from one that we need to protect humans from sharks to one where we must protect sharks from humans, has added to calls for better management. The present paper examines the growing need for research for conservation management of sharks and rays by synthesising information presented in this Special Issue from the 2010 Sharks International Conference and by identifying future research needs, including topics such as taxonomy, life history, population status, spatial ecology, environmental effects, ecosystem role and human impacts. However, this biological and ecological research agenda will not be sufficient to fully secure conservation management. There is also a need for research to inform social and economic sustainability. Effective conservation management will be achieved by setting clear priorities for research with the aid of stakeholders, implementing well designed research projects, building the capacity for research, and clearly communicating the results to stakeholders. If this can be achieved, it will assure a future for this iconic group, the ecosystems in which they occur and the human communities that rely on them. DOI
9. Sparks, TH; Butchart, SHM; Balmford, A; Bennun, L; Stanwell-Smith, D; Walpole, M; Bates, NR; Bomhard, B; Buchanan, GM; Chenery, AM; Collen, B; Csirke, J; Diaz, RJ; Dulvy, NK; Fitzgerald, C; Kapos, V; Mayaux, P; Tierney, M; Waycott, M; Wood, L; Green, RE. (2011) Linked indicator sets for addressing biodiversity loss.Oryx 45: 411-419 Linked indicator sets for addressing biodiversity loss
2010 target; CBD; Convention on Biological Diversity; ecosystem services; humid tropical forest; marine fisheries; response
The target adopted by world leaders of significantly reducing the rate of biodiversity loss by 2010 was not met but this stimulated a new suite of biodiversity targets for 2020 adopted by the Parties to the Convention on Biological Diversity (CBD) in October 2010. Indicators will be essential for monitoring progress towards these targets and the CBD will be defining a suite of relevant indicators, building on those developed for the 2010 target. Here we argue that explicitly linked sets of indicators offer a more useful framework than do individual indicators because the former are easier to understand, communicate and interpret to guide policy. A Response-Pressure-State-Benefit framework for structuring and linking indicators facilitates an understanding of the relationships between policy actions, anthropogenic threats, the status of biodiversity and the benefits that people derive from it. Such an approach is appropriate at global, regional, national and local scales but for many systems it is easier to demonstrate causal linkages and use them to aid decision making at national and local scales. We outline examples of linked indicator sets for humid tropical forests and marine fisheries as illustrations of the concept and conclude that much work remains to be done in developing both the indicators and the causal links between them. DOI
8. Sunday, JM; Bates, AE; Dulvy, NK. (2011) Global analysis of thermal tolerance and latitude in ectotherms.Proceedings of the Royal Society B-Biological Sciences 278: 1823-1830 Global analysis of thermal tolerance and latitude in ectotherms
macroecology; macrophysiology; thermal tolerance breadth; latitude; thermal niche; climate variability hypothesis
A tenet of macroecology is that physiological processes of organisms are linked to large-scale geographical patterns in environmental conditions. Species at higher latitudes experience greater seasonal temperature variation and are consequently predicted to withstand greater temperature extremes. We tested for relationships between breadths of thermal tolerance in ectothermic animals and the latitude of specimen location using all available data, while accounting for habitat, hemisphere, methodological differences and taxonomic affinity. We found that thermal tolerance breadths generally increase with latitude, and do so at a greater rate in the Northern Hemisphere. In terrestrial ectotherms, upper thermal limits vary little while lower thermal limits decrease with latitude. By contrast, marine species display a coherent poleward decrease in both upper and lower thermal limits. Our findings provide comprehensive global support for hypotheses generated from studies at smaller taxonomic subsets and geographical scales. Our results further indicate differences between terrestrial and marine ectotherms in how thermal physiology varies with latitude that may relate to the degree of temperature variability experienced on land and in the ocean. DOI
7. Chassot, E; Bonhommeau, S; Dulvy, NK; Melin, F; Watson, R; Gascuel, D; Le Pape, O. (2010) Global marine primary production constrains fisheries catches.Ecology Letters 13: 495-505 Global marine primary production constrains fisheries catches
Bottom-up; Large Marine Ecosystem; quantile regression; sustainable fishing
P>Primary production must constrain the amount of fish and invertebrates available to expanding fisheries; however the degree of limitation has only been demonstrated at regional scales to date. Here we show that phytoplanktonic primary production, estimated from an ocean-colour satellite (SeaWiFS), is related to global fisheries catches at the scale of Large Marine Ecosystems, while accounting for temperature and ecological factors such as ecosystem size and type, species richness, animal body size, and the degree and nature of fisheries exploitation. Indeed we show that global fisheries catches since 1950 have been increasingly constrained by the amount of primary production. The primary production appropriated by current global fisheries is 17-112% higher than that appropriated by sustainable fisheries. Global primary production appears to be declining, in some part due to climate variability and change, with consequences for the near future fisheries catches. DOI
6. Hoffmann, M; Hilton-Taylor, C; Angulo, A; Bohm, M; Brooks, TM; Butchart, SHM; Carpenter, KE; Chanson, J; Collen, B; Cox, NA; Darwall, WRT; Dulvy, NK; Harrison, LR; Katariya, V; Pollock, CM; Quader, S; Richman, NI; Rodrigues, ASL; Tognelli, MF; Vie, JC; Aguiar, JM; Allen, DJ; Allen, GR; Amori, G; Ananjeva, NB; Andreone, F; Andrew, P; Ortiz, ALA; Baillie, JEM; Baldi, R; Bell, BD; Biju, SD; Bird, JP; Black-Decima, P; Blanc, JJ; Bolanos, F; Bolivar, W; Burfield, IJ; Burton, JA; Capper, DR; Castro, F; Catullo, G; Cavanagh, RD; Channing, A; Chao, NL; Chenery, AM; Chiozza, F; Clausnitzer, V; Collar, NJ; Collett, LC; Collette, BB; Fernandez, CFC; Craig, MT; Crosby, MJ; Cumberlidge, N; Cuttelod, A; Derocher, AE; Diesmos, AC; Donaldson, JS; Duckworth, JW; Dutson, G; Dutta, SK; Emslie, RH; Farjon, A; Fowler, S; Freyhof, J; Garshelis, DL; Gerlach, J; Gower, DJ; Grant, TD; Hammerson, GA; Harris, RB; Heaney, LR; Hedges, SB; Hero, JM; Hughes, B; Hussain, SA; Icochea, J; Inger, RF; Ishii, N; Iskandar, DT; Jenkins, RKB; Kaneko, Y; Kottelat, M; Kovacs, KM; Kuzmin, SL; La Marca, E; Lamoreux, JF; Lau, MWN; Lavilla, EO; Leus, K; Lewison, RL; Lichtenstein, G; Livingstone, SR; Lukoschek, V; Mallon, DP; McGowan, PJK; McIvor, A; Moehlman, PD; Molur, S; Alonso, AM; Musick, JA; Nowell, K; Nussbaum, RA; Olech, W; Orlov, NL; Papenfuss, TJ; Parra-Olea, G; Perrin, WF; Polidoro, BA; Pourkazemi, M; Racey, PA; Ragle, JS; Ram, M; Rathbun, G; Reynolds, RP; Rhodin, AGJ; Richards, SJ; Rodriguez, LO; Ron, SR; Rondinini, C; Rylands, AB; de Mitcheson, YS; Sanciangco, JC; Sanders, KL; Santos-Barrera, G; Schipper, J; Self-Sullivan, C; Shi, YC; Shoemaker, A; Short, FT; Sillero-Zubiri, C; Silvano, DL; Smith, KG; Smith, AT; Snoeks, J; Stattersfield, AJ; Symes, AJ; Taber, AB; Talukdar, BK; Temple, HJ; Timmins, R; Tobias, JA; Tsytsulina, K; Tweddle, D; Ubeda, C; Valenti, SV; van Dijk, PP; Veiga, LM; Veloso, A; Wege, DC; Wilkinson, M; Williamson, EA; Xie, F; Young, BE; Akcakaya, HR; Bennun, L; Blackburn, TM; Boitani, L; Dublin, HT; da Fonseca, GAB; Gascon, C; Lacher, TE; Mace, GM; Mainka, SA; McNeely, JA; Mittermeier, RA; Reid, GM; Rodriguez, JP; Rosenberg, AA; Samways, MJ; Smart, J; Stein, BA; Stuart, SN. (2010) The Impact of Conservation on the Status of the World's Vertebrates.Science 330: 1503-1509 The Impact of Conservation on the Status of the World's Vertebrates
Using data for 25,780 species categorized on the International Union for Conservation of Nature Red List, we present an assessment of the status of the world's vertebrates. One-fifth of species are classified as Threatened, and we show that this figure is increasing: On average, 52 species of mammals, birds, and amphibians move one category closer to extinction each year. However, this overall pattern conceals the impact of conservation successes, and we show that the rate of deterioration would have been at least one-fifth again as much in the absence of these. Nonetheless, current conservation efforts remain insufficient to offset the main drivers of biodiversity loss in these groups: agricultural expansion, logging, overexploitation, and invasive alien species. DOI
5. MacNeil, MA; Graham, NAJ; Cinner, JE; Dulvy, NK; Loring, PA; Jennings, S; Polunin, NVC; Fisk, AT; McClanahan, TR. (2010) Transitional states in marine fisheries: adapting to predicted global change.Philosophical Transactions of the Royal Society B-Biological Sciences 365: 3753-3763 Transitional states in marine fisheries: adapting to predicted global change
climate change; fish communities; social-ecological systems; biodiversity
Global climate change has the potential to substantially alter the production and community structure of marine fisheries and modify the ongoing impacts of fishing. Fish community composition is already changing in some tropical, temperate and polar ecosystems, where local combinations of warming trends and higher environmental variation anticipate the changes likely to occur more widely over coming decades. Using case studies from the Western Indian Ocean, the North Sea and the Bering Sea, we contextualize the direct and indirect effects of climate change on production and biodiversity and, in turn, on the social and economic aspects of marine fisheries. Climate warming is expected to lead to (i) yield and species losses in tropical reef fisheries, driven primarily by habitat loss; (ii) community turnover in temperate fisheries, owing to the arrival and increasing dominance of warm-water species as well as the reduced dominance and departure of cold-water species; and (iii) increased diversity and yield in Arctic fisheries, arising from invasions of southern species and increased primary production resulting from ice-free summer conditions. How societies deal with such changes will depend largely on their capacity to adapt-to plan and implement effective responses to change-a process heavily influenced by social, economic, political and cultural conditions. DOI
3. Vergnon, R; Dulvy, NK; Freckleton, RP. (2009) Niches versus neutrality: uncovering the drivers of diversity in a species-rich community.Ecology Letters 12: 1079-1090 Niches versus neutrality: uncovering the drivers of diversity in a species-rich community
ABUNDANCE DISTRIBUTIONS; RELATIVE ABUNDANCE; BIODIVERSITY; PHYTOPLANKTON; COEXISTENCE; DYNAMICS; PLANKTON; ECOLOGY; MODEL; SIZE
Ecological models suggest that high diversity can be generated by purely niche-based, purely neutral or by a mixture of niche-based and neutral ecological processes. Here, we compare the degree to which four contrasting hypotheses for coexistence, ranging from niche-based to neutral, explain species richness along a body mass niche axis. We derive predictions from these hypotheses and confront them with species body-mass patterns in a highly sampled marine phytoplankton community. We find that these patterns are consistent only with a mechanism that combines niche and neutral processes, such as the emergent neutrality mechanism. In this work, we provide the first empirical evidence that a niche-neutral model can explain niche space occupancy pattern in a natural species-rich community. We suggest this class of model may be a useful hypothesis for the generation and maintenance of species diversity in other size-structured communities. DOI
2. Wilson, SK; Fisher, R; Pratchett, MS; Graham, NAJ; Dulvy, NK; Turner, RA; Cakacaka, A; Polunin, NVC; Rushton, SP. (2008) Exploitation and habitat degradation as agents of change within coral reef fish communities.Global Change Biology 14: 2796-2809 Exploitation and habitat degradation as agents of change within coral reef fish communities
climate change; density dependence; disturbance; food webs; trophic cascades GREAT-BARRIER-REEF; SOUTH-EASTERN AUSTRALIA; TROPHIC CASCADES; CLIMATE-CHANGE; MARINE RESERVES; TOP-DOWN; BOTTOM-UP; FOOD WEBS; ECOSYSTEMS; FISHERIES
Over-exploitation and habitat degradation are the two major drivers of global environmental change and are responsible for local extinctions and declining ecosystem services. Here we compare the top-down effect of exploitation by fishing with the bottom-up influence of habitat loss on fish communities in the most diverse of ecological systems, coral reefs. Using a combination of multivariate techniques and path analyses, we illustrate that the relative importance of coral cover and fishing in controlling fish abundance on remote Fijian reefs varies between species and functional groups. A decline in branching Acropora coral is strongly associated with a decline in abundance of coral-feeding species, and a decrease in coral-associated habitat complexity, which has indirectly contributed to reduced abundance of small-bodied damselfish. In contrast, reduced fishing pressure, brought about by declining human populations and a shift to alternate livelihoods, is associated with increased abundance of some piscivores and fisheries target species. However, availability of prey is controlled by coral-associated habitat complexity and appears to be a more important driver of total piscivore abundance compared with fishing pressure. Effects of both fishing and coral loss are stronger on individual species than functional groups, as variation in the relative importance of fishing or coral loss among species within the same functional group attenuated the impact of either of these potential drivers at the functional level. Overall, fishing continues to have an influence on Fijian fish communities; however, habitat loss is currently the overriding agent of change. The importance of coral loss mediated by climate change is expected to have an increasing contribution to fish community dynamics, particularly in remote locations or where the influence of fishing is waning. DOI
1. Newton, K; Côté, IM; Pilling, GM; Jennings, S; Dulvy, NK. (2007) Current and future sustainability of island coral reef fisheries.Current Biology 17: 655-658 Current and future sustainability of island coral reef fisheries
Overexploitation is one of the principal threats to coral reef diversity, structure, function, and resilience [1, 2]. Although it is generally held that coral reef fisheries are unsustainable [3-5], little is known of the overall scale of exploitation or which reefs are overfished [6]. Here, on the basis of ecological footprints and a review of exploitation status [7, 8], we report widespread unsustainability of island coral reef fisheries. Over half (55%) of the 49 island countries considered are exploiting their coral reef fisheries in an unsustainable way. We estimate that total landings of coral reef fisheries are currently 64% higher than can be sustained. Consequently, the area of coral reef appropriated by fisheries exceeds the available effective area by similar to 75,000 km(2), or 3.7 times the area of Australia's Great Barrier Reef, and an extra 196,000 km(2) of coral reef may be required by 2050 to support the anticipated growth in human populations. The large overall imbalance between current and sustainable catches implies that management methods to reduce social and economic dependence on reef fisheries are essential to prevent the collapse of coral reef ecosystems while sustaining the well-being of burgeoning coastal populations. DOI
