Extinction risk and conservation of the world’s sharks and rays

TLDR

Rapid human expansion threatens ocean biodiversity, causing marine population declines, yet it is unclear whether these trends indicate a chronic global extinction risk, underscoring the need for improved fisheries and trade management. The study presents the first systematic threat analysis of 1,041 globally distributed chondrichthyan species (sharks, rays, chimaeras). The authors conducted a systematic threat assessment of 1,041 chondrichthyan species worldwide. The analysis estimates that 25 % of chondrichthyan species are threatened, primarily due to overfishing, with large‑bodied shallow‑water species and rays at greatest risk; overall extinction risk exceeds that of most vertebrates, with only one‑third of species considered safe, and population depletion is widespread, especially in the Indo‑Pacific Biodiversity Triangle and Mediterranean Sea.

Abstract

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.