Predicting the conservation status of Europe’s Data Deficient sharks and rays

Abstract

Shark and ray biodiversity is threatened primarily by overfishing and the globalisation of trade, and Europe has been one of the most documented heavily fished regions for a relatively long time. Yet, we have little idea of the conservation status of the hundreds of Data Deficient shark and ray species. It is important to derive some insight into the status of these species, both to understand global extinction rates and also to ensure that any threatened Data Deficient species are not overlooked in conservation planning. Here, we developed a biological and ecological trait model to predict the categorical conservation status of 26 Northeast Atlantic and 15 Mediterranean Sea Data Deficient sharks and rays. We first developed an explanatory model based on all species evaluated on the International Union for Conservation of Nature (IUCN) Red List of Threatened SpeciesTM, using maximum body size, median depth (as a proxy for fisheries exposure), and reproductive mode, and then predicted the status of all Data Deficient species. Almost half of Northeast Atlantic (46%, n=12 of 26), and two-thirds of Mediterranean (67%, n=10 of 15) Data Deficient species are predicted to be in one of the three IUCN threatened categories. Northeast Atlantic Data Deficient species are predicted to be 1.2 times more threatened than evaluated species (38%, n=36 of 94), whereas threat levels in the Mediterranean Sea are relative for each (66%, n=38 of 58). This case study is intended for extrapolation to the global shark and ray dataset upon completion of the global IUCN Red List assessment. Trait-based, categorical prediction of conservation status is a cost-effective approach towards incorporating Data Deficient species into (i) estimates of lineage-wide extinction rates, (ii) revised protected species lists, and (iii) Red List Indices, thus preventing poorly known species from reaching extinction unnoticed.

Batoid Abundances, Spatial Distribution, and Life History Traits in the Strait of Sicily (Central Mediterranean Sea): Bridging a Knowledge Gap through Three Decades of Survey

“…Therefore, these species were neither recorded in the official landing statistics nor in the first experimental surveys (see, in [ 5 , 6 ]). Thereafter, facing the decline in the more productive target bony and shellfish species and the increasing demand of markets, fishers began to retain and land large batoids, returning to the sea only the small or damaged specimens [ 7 ].…”

Linking dimensions of data on global marine animal diversity

“…In terrestrial conservation, considerable concern has been expressed over the likely conservation status of species too poorly known to formally assess, as they tend to have characteristics (rarity, small ranges, occurring in poorly studied regions) which will predispose them to be at risk [56]. For some marine taxa this appears to be the case too, with high rates of extinction risk predicted for European sharks and rays formally assessed as Data Deficient [57], and low levels of conservation assessment in poorly-known marine groups may contribute to low overall documented levels of extinction risk [58]. On the other hand, the fact that the biggest data gaps in marine biodiversity tend to be in remote habitats largely inaccessible to humans (e.g.…”

“…Given the acceleration of human activities into previously unexploited regions of the oceans [64], with new threats including deep sea mining [65] and exploitation of the mesopelagic [66], it seems unwise to assume that the large fraction of marine biodiversity that remains poorly known is not at risk. Given the fact that Data Deficient conservation assessments are twice as frequent in marine versus non-marine taxa [34], data-driven predictive conservation assessments [58,67,68], which rely on some of the kinds of data we consider here (spatial distribution, evolutionary relationships and ecological guilds) combined with biological traits, may prove to be especially valuable tools. The aim of this study was to flag priorities for future work.…”