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 gap leads to uncertainty about 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

Biology and conservation of elasmobranchs: an introduction to the collection

Elasmobranchs, the taxonomic group comprising sharks, skates and rays, play important roles in society and marine ecology but several species in this subclass are under threat. This collection aims to be an open access hub for articles concerning all areas of elasmobranch biology and conservation. The collection is indefinitely open to further submissions and so will continue to grow as additional articles are added

DNA barcoding unveils skate (Chondrichthyes: Rajidae) species diversity in ‘ray’ products sold across Ireland and the UK

Skates are widely consumed across the globe, but many large species are subject to considerable concern regarding their conservation and management. Within Europe such issues have recently driven policy changes so that, for the first time, reports of skate landings now have to be made under species-specific names. Total allowable catches have also been established for many groups, which have been set to zero for a number of the most vulnerable species (e.g., Dipturus batis, Raja undulata and Rostoraja alba. Whilst accurate species identification has become an important issue for landings, the sale of skates is still usually made under a blanket term of “skate” or “ray”. The matter of identifying species of skate is further complicated by their morphologically conservative nature and the fact that they are commercially valued for their wings. Thus, before sale their bodies are usually discarded (i.e., “winged”) and often skinned, making morphological identification impossible. For the first time, DNA barcoding (of the mitochondrial COI gene) was applied to samples of skate wings from retail outlets across the British Isles, providing insight into which species are sold for consumption. A total of 98 wing samples were analysed, revealing that six species were sold; blonde ray (Raja brachyura), spotted ray (Raja montagui), thornback ray (Raja clavata), cuckoo ray (Leucoraja naevus) small-eyed ray (Raja microocellata) and shagreen ray (Leucoraja fullonica). Statistical testing demonstrated that there were significant differences in the species sold in the distinct retail groups which suggests complex drivers behind the patterns of sale in skates. The results also indicate that endangered species are not commonly being passed on to consumers. In addition, the practice of selling skate wings under ambiguous labels is highlighted as it makes it extremely difficult for consumers to exercise a right to avoid species of conservation concern. Interestingly, a single retailer chain labelled their wings as originating from three smaller-growing species (generally to be considered of lower conservation concern); of the six samples analysed from this company a third were mislabelled and originated from the thornback ray (a larger species that is currently undergoing population declines)

Extinction risk and conservation of the world\u27s 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\u27s 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

Early life sensory ability—ventilatory responses of thornback ray embryos (Raja clavata) to predator-type electric fields

Predator avoidance is fundamental for survival and it can be particularly challenging for prey animals if physical movement away from a predatory threat is restricted. Many sharks and rays begin life within an egg capsule that is attached to the sea bed. The vulnerability of this sedentary life stage is exacerbated in skates (Rajidae) as the compulsory ventilatory activity of embryos makes them conspicuous to potential predators. Embryos can reduce this risk by mediating ventilatory activity if they detect the presence of a predator using an acute electrosense. To determine how early in embryonic life predator elicited behavioral responses can occur, the reactions of three different age groups (1/3 developed, 2/3 developed, and near hatching) of embryonic thornback rays Raja clavata were tested using predator-type electric field stimuli. Egg capsules were exposed to continuous or intermittent stimuli in order to assess varying predator-type encounter scenarios on the ventilatory behavior of different developmental stages. All embryos reacted with a “freeze response” following initial electric field (E-field) exposure, ceasing ventilatory behavior in response to predator presence, demonstrating electroreceptive functionality for the first time at the earliest possible stage in ontogeny. This ability coincided with the onset of egg ventilatory behavior and may represent an effective means to enhance survival. A continuous application of stimuli over time revealed that embryos can adapt their behavior and resume normal activity, whereas when presented intermittently, the E-field resulted in a significant reduction in overall ventilatory activity across all ages. Recovery from stimuli was significantly quicker in older embryos, potentially indicative of the trade-off between avoiding predation and adequate respiration. © 2015 Wiley Periodicals, Inc. Develop Neurobiol 76: 721–729, 201

Why Have Global Shark and Ray Landings Declined: Improved Management or Overfishing?

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 has been made, country-level fisheries management measures do 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

Global Patterns of Extinction Risk in Marine and Non-marine Systems

SummaryDespite increasing concern over the effects of human activities on marine ecosystems [1, 2], extinction in the sea remains scarce: 19–24 out of a total of >850 recorded extinctions [3, 4] implies a 9-fold lower marine extinction rate compared to non-marine systems. The extent of threats faced by marine systems, and their resilience to them, receive considerable attention [2, 4–6], but the detectability of marine extinctions is less well understood. Before its extinction or threat status is recorded, a species must be both taxonomically described and then formally assessed; lower rates of either process for marine species could thus impact patterns of extinction risk, especially as species missing from taxonomic inventories may often be more vulnerable than described species [7–11]. We combine data on taxonomic description with conservation assessments from the International Union for Conservation of Nature (IUCN) to test these possibilities across almost all marine and non-marine eukaryotes. We find that the 9-fold lower rate of recorded extinctions and 4-fold lower rate of ongoing extinction risk across marine species can be explained in part by differences in the proportion of species assessed by the IUCN (3% cf. 4% of non-marine species). Furthermore, once taxonomic knowledge and conservation assessments pass a threshold level, differences in extinction risk between marine and non-marine groups largely disappear. Indeed, across the best-studied taxonomic groups, there is no difference between marine and non-marine systems, with on average between 20% and 25% of species being threatened with extinction, regardless of realm

Counting the cost of overfishing on sharks and rays

Over half of all shark and ray species are at risk of extinction or at least heading that way

The Conservation and Management of Tunas and Their Relatives: Setting Life History Research Priorities

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