Overfishing and climate change elevate extinction risk of endemic sharks and rays in the southwest Indian Ocean hotspot.

Here, we summarise the extinction risk of the sharks and rays endemic to coastal, shelf, and slope waters of the southwest Indian Ocean and adjacent waters (SWIO+, Namibia to Kenya, including SWIO islands). This region is a hotspot of endemic and evolutionarily distinct sharks and rays. Nearly one-fifth (n = 13 of 70, 18.

Fishing for oil and meat drives irreversible defaunation of deepwater sharks and rays.

The deep ocean is the last natural biodiversity refuge from the reach of human activities. Deepwater sharks and rays are among the most sensitive marine vertebrates to overexploitation. One-third of threatened deepwater sharks are targeted, and half the species targeted for the international liver-oil trade are threatened with extinction.

Size-dependence of food intake and mortality interact with temperature and seasonality to drive diversity in fish life histories.

Understanding how growth and reproduction will adapt to changing environmental conditions is a fundamental question in evolutionary ecology, but predicting the responses of specific taxa is challenging. Analyses of the physiological effects of climate change upon life history evolution rarely consider alternative hypothesized mechanisms, such as size-dependent foraging and the risk of predation, simultaneously shaping optimal growth patterns. To test for interactions between these mechanisms, we embedded a state-dependent energetic model in an ecosystem size-spectrum to ask whether prey availability (foraging) and risk of predation experienced by individual fish can explain observed diversity in life histories of fishes.

A multi-taxon analysis of European Red Lists reveals major threats to biodiversity.

Biodiversity loss is a major global challenge and minimizing extinction rates is the goal of several multilateral environmental agreements. Policy decisions require comprehensive, spatially explicit information on species' distributions and threats. We present an analysis of the conservation status of 14,669 European terrestrial, freshwater and marine species (ca.

Tail shape and the swimming speed of sharks.

Trait-based ecology is a rapidly growing approach for developing insights and predictions for data-poor species. Caudal tail fin shape has the potential to reveal much about the energetics, activity and ecology of fishes and can be rapidly measured from field guides, which is particularly helpful for data-sparse species. One outstanding question is whether swimming speed in sharks is related to two morphological traits: caudal fin aspect ratio (CFAR, height/tail area) and caudal lobe asymmetry ratio (CLAR).

The allometric scaling of oxygen supply and demand in the California horn shark, Heterodontus francisci.

The gill surface area of aquatic ectotherms is thought to be closely linked to the ontogenetic scaling of metabolic rate, a relationship that is often used to explain and predict ecological patterns across species. However, there are surprisingly few within-species tests of whether metabolic rate and gill area scale similarly. We examined the relationship between oxygen supply (gill area) and demand (metabolic rate) by making paired estimates of gill area with resting and maximum metabolic rates across ontogeny in the relatively inactive California horn shark, Heterodontus francisci.

Conservation successes and challenges for wide-ranging sharks and rays.

Overfishing is the most significant threat facing sharks and rays. Given the growth in consumption of seafood, combined with the compounding effects of habitat loss, climate change, and pollution, there is a need to identify recovery paths, particularly in poorly managed and poorly monitored fisheries. Here, we document conservation through fisheries management success for 11 coastal sharks in US waters by comparing population trends through a Bayesian state-space model before and after the implementation of the 1993 Fisheries Management Plan for Sharks.

Half a century of rising extinction risk of coral reef sharks and rays.

Sharks and rays are key functional components of coral reef ecosystems, yet many populations of a few species exhibit signs of depletion and local extinctions. The question is whether these declines forewarn of a global extinction crisis. We use IUCN Red List to quantify the status, trajectory, and threats to all coral reef sharks and rays worldwide.

Seventy years of tunas, billfishes, and sharks as sentinels of global ocean health.

Fishing activity is closely monitored to an increasing degree, but its effects on biodiversity have not received such attention. Using iconic and well-studied fish species such as tunas, billfishes, and sharks, we calculate a continuous Red List Index of yearly changes in extinction risk over 70 years to track progress toward global sustainability and biodiversity targets. We show that this well-established biodiversity indicator is highly sensitive and responsive to fishing mortality.

Body mass, temperature, and depth shape the maximum intrinsic rate of population increase in sharks and rays.

An important challenge in ecology is to understand variation in species' maximum intrinsic rate of population increase, , not least because underpins our understanding of the limits of fishing, recovery potential, and ultimately extinction risk. Across many vertebrate species, terrestrial and aquatic, body mass and environmental temperature are important correlates of . In sharks and rays, specifically, is known to be lower in larger species, but also in deep sea ones.

Sharkipedia: a curated open access database of shark and ray life history traits and abundance time-series.

A curated database of shark and ray biological data is increasingly necessary both to support fisheries management and conservation efforts, and to test the generality of hypotheses of vertebrate macroecology and macroevolution. Sharks and rays are one of the most charismatic, evolutionary distinct, and threatened lineages of vertebrates, comprising around 1,250 species. To accelerate shark and ray conservation and science, we developed Sharkipedia as a curated open-source database and research initiative to make all published biological traits and population trends accessible to everyone.

Current and future considerations for shark conservation in the Northeast and Eastern Central Pacific Ocean.

Sharks are iconic and ecologically important predators found in every ocean. Because of their ecological role as predators, some considered apex predators, and concern over the stability of their populations due to direct and indirect overfishing, there has been an increasing amount of work focussed on shark conservation, and other elasmobranchs such as skates and rays, around the world. Here we discuss many aspects of current shark science and conservation and the path to the future of shark conservation in the Northeastern and Eastern Central Pacific.

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.

The role and value of science in shark conservation advocacy.

Many species of sharks are threatened with extinction, and there has been a longstanding debate in scientific and environmental circles over the most effective and appropriate strategy to conserve and protect them. Should we allow for sustainable fisheries exploitation of species which can withstand fishing pressure, or ban all fisheries for sharks and trade in shark products? In the developing world, exploitation of fisheries resources can be essential to food security and poverty alleviation, and global management efforts are typically focused on sustainably maximizing economic benefits. This approach aligns with traditional fisheries management and the perspectives of most surveyed scientific researchers who study sharks.

Analytical methods matter too: Establishing a framework for estimating maximum metabolic rate for fishes.

Advances in experimental design and equipment have simplified the collection of maximum metabolic rate (MMR) data for a more diverse array of water-breathing animals. However, little attention has been given to the consequences of analytical choices in the estimation of MMR. Using different analytical methods can reduce the comparability of MMR estimates across species and studies and has consequences for the burgeoning number of macroecological meta-analyses using metabolic rate data.

Tracking the rising extinction risk of sharks and rays in the Northeast Atlantic Ocean and Mediterranean Sea.

The loss of biodiversity is increasingly well understood on land, but trajectories of extinction risk remain largely unknown in the ocean. We present regional Red List Indices (RLIs) to track the extinction risk of 119 Northeast Atlantic and 72 Mediterranean shark and ray species primarily threatened by overfishing. We combine two IUCN workshop assessments from 2003/2005 and 2015 with a retrospective backcast assessment for 1980.

The metabolic pace of life histories across fishes.

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.

Gill surface area provides a clue for the respiratory basis of brain size in the blacktip shark (Carcharhinus limbatus).

Brain size varies dramatically, both within and across species, and this variation is often believed to be the result of trade-offs between the cognitive benefits of having a large brain for a given body size and the energetic cost of sustaining neural tissue. One potential consequence of having a large brain is that organisms must also meet the associated high energetic demands. Thus, a key question is whether metabolic rate correlates with brain size.

Respiratory capacity is twice as important as temperature in explaining patterns of metabolic rate across the vertebrate tree of life.

Metabolic rate underlies a wide range of phenomena from cellular dynamics to ecosystem structure and function. Models seeking to statistically explain variation in metabolic rate across vertebrates are largely based on body size and temperature. Unexpectedly, these models overlook variation in the size of gills and lungs that acquire the oxygen needed to fuel aerobic processes.