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

TL;DR

This study systematically assesses extinction risks for sharks, rays, and chimaeras, revealing that about 25% are threatened mainly due to overfishing, with higher risks in shallow, large-bodied species, especially rays.

Contribution

First comprehensive global threat assessment of chondrichthyan fishes, highlighting extinction risks and geographic hotspots, informing conservation priorities.

Findings

Approximately 25% of species are threatened according to IUCN criteria.

Large-bodied, shallow-water species face the highest risk.

Extinction risk is higher than for most other vertebrates.

Abstract

The rapid expansion of human activities threatens ocean-wide biodiversity loss. 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.