Overfishing of sharks and rays has depleted many populations, causing widespread erosion of ecological function and exceptionally high extinction risk. NOAA Fisheries coauthored a study in the journal Science that quantifies the extinction risk for the world’s 1,199 sharks and ray species over 50 years. They found that while sharks and rays are at high risk of extinction and biodiversity loss globally, this risk differs by habitat and region. There are some “bright spots” that could help species survive.

Sharks Are In Rough Shape Globally

We found that sharks and rays globally are in a worse conservation state than all other vertebrate groups, apart from amphibians. We also demonstrated the “fishing down” of shark and ray biodiversity and ecosystem function. This shows that the largest species declined first and most rapidly.

Most sharks and rays have slow population growth rates, which makes them highly vulnerable to overfishing and subsequently takes populations longer to rebuild. Around the world, sharks and rays are targeted for their fins, meat, gill plates, and liver oil. They are also caught incidentally—as bycatch—in other fisheries.

Extinction Risk Differs by Habitat and Region

We investigated the differences in extinction risk by habitat. We found that areas that are difficult to fish—such as kelp forests, rocky reefs, and the deep sea—provide some refuge where extinction risk is lower. Inversely, this risk was greatest in more accessible fishing grounds like inland wetlands and other areas that are closer to population centers.

The Red List Index, maintained by the International Union for Conservation of Nature, shows trends in overall extinction risk for species. While NOAA Fisheries doesn’t use the IUCN Red List Index when developing fishery management plans, we do share the IUCN’s concern for sharks. We continue to use our authority under the Endangered Species Act and Magnuson-Stevens Act to protect and recover listed and overfished species.

We mapped bright spots—areas of high species richness with little change in the Red List Index value. We also mapped dark spots—areas of high species richness with steep declines in the index value. This allowed us to identify regions that may serve as a haven for shark and ray biodiversity. Countries with sustainably managed fisheries like the United States have lower biodiversity loss for sharks and rays compared to areas with no or little management of their shark fisheries. Other “bright spots” with lower loss of biodiversity include:

• Canada
• The Northeast Atlantic west of Scotland, Ireland, France, Spain, and Portugal
• The southwestern cape of South Africa
• Australia and New Zealand

Risk was greater in countries with under-managed fisheries and high fishing pressure. This is driven by lower catch-per-unit-effort of sharks and rays, large coastal human population sizes, and poor economic incentives or subsidies.

Sharks and Ray Threats and Conservation Measures

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While shark and ray losses are primarily due to overfishing, additional emerging threats may hinder recovery including:

• Increasing loss of coastal habitats
• Poleward shifts of some species due to climate change
• Sublethal effects of pollutants

A loss of biodiversity can lead to ecological erosion—the process of losing key species that provide an important ecological niche. This could cause cascading effects throughout marine ecosystems. Further loss of biodiversity and ecosystem function would be detrimental to humanity. Billions of people around the world rely on oceans as a direct source of nutrition and a means of income.

Shark and ray fisheries management and conservation efforts have increased in the past decade. This includes international trade regulations for more than 143 shark and ray species encompassing more than 85 percent of the global fin trade.

The United States is home to some of the largest and best-managed marine fisheries in the world. We have both the opportunity and responsibility to advance sustainable conservation and management practices on the high seas. As appropriate, we also have the chance to support other nations in achieving similar outcomes in their economic zones. NOAA Fisheries' science-based conservation and management of sustainable fisheries have become global models for marine stewardship and sustainability.