What is the global status of sharks and rays?

Declines in top predator fish populations, such as sharks, have significant implications in marine ecosystems, with decreases in diversity and productivity, loss of ecosystem services and, in some instances, ecosystem... [ view full abstract ]

Declines in top predator fish populations, such as sharks, have significant implications in marine ecosystems, with decreases in diversity and productivity, loss of ecosystem services and, in some instances, ecosystem collapse. Previous studies suggest that up to 90% of large predatory fishes have been lost since the 1950s and 16% of all shark species are threatened with extinction.

There are 21 pelagic sharks and rays species and 75% classified as Threatened or Near Threatened in 2008. Conservation and management efforts for these species are complex - their vast ranges expose them not only to over-exploitation and being bycaught in high seas fisheries but also result in a lack of protective legislation due to insufficient coordination across national jurisdictions. Furthermore, their slow intrinsic rates of population growth and slow rate to maturity make them particularly vulnerable to exploitation.

Populations must be monitored and well-managed given their ecological significance as top predators. Regional Fisheries Management Organisations are primarily responsible for serving this role, although their ability to undertake full stock assessments is limited due to data deficiencies. To identify species at risk of extinction, we assess the current global status of pelagic sharks and rays by analyzing population time-series literature, with a particular focus on regional variations within species. The analysis utilizes the Living Planet Index approach, applying the generalized additive modelling framework to identify underlying trends within each population time-series. The findings will provide insight into the current regional and national conservation needs for pelagic sharks and rays.