Quarter of world’s freshwater fish at risk of extinction, according to assessment | Fish

Almost a quarter of the world’s freshwater fish are at risk of extinction due to global warming, overfishing and pollution, according to an expert assessment.

From the big-toothed Lake Turkana robber in Kenya to the Mekong giant catfish in Southeast Asia, many of the world’s freshwater fish are at risk of disappearing, the first International Union for Conservation of Nature (IUCN) red list assessment of the category found has.

Almost a fifth of all endangered freshwater species are affected by climate change, from impacts such as falling water levels, shifting seasons and seawater moving up rivers. Of the assessed species, 3,086 out of 14,898 were in danger of disappearing.

The latest assessment also found that mahogany, Atlantic salmon and green turtles are increasingly threatened according to scientific estimates, but there was good news for the saiga goat, which moved from the critically endangered category to near threatened after its population increased by 1,100% in just seven years, mainly in Kazakhstan .

The reintroduction of the scimitar-horned oryx in Chad is another success story. The mammal was once common across the Sahel, but disappeared in the 1990s after being overhunted. Reintroduction efforts from captivity have resulted in the population growing to 140 mature animals in the Ouadi Rimé-Ouadi Achim Fauna Reserve in Chad. It is classified as vulnerable to extinction and scientists say it is threatened by the climate crisis.

“Today’s update of the IUCN Red List demonstrates the power of coordinated local, national and international conservation efforts. Success stories like that of the hornwort show that conservation works. To ensure that the results of conservation actions are durable, we must decisively tackle the interconnected climate and biodiversity crises,” said IUCN President Razan Al Mubarak.

Bigleaf Mahogany, one of the most commercially sought after plants on the planet, is now classified as endangered after its numbers have declined by 60% over the past 180 years due to unsustainable harvesting. Mahogany wood remains valuable for furniture, musical instruments and decorations, which has led to the illegal felling of the tree across Central and South America.

The Atlantic salmon, previously common and classed as a species of least concern, is now Near Threatened on the IUCN Red List after its global population has fallen by 23%, having disappeared from many UK rivers. The fish, which live in both fresh and salt water, have been affected by widespread habitat loss, global warming and dams blocking access to breeding grounds. Breeding with farmed salmon has also weakened their ability to adapt to global warming as invasive Pacific pink salmon spread across northern Europe.

“Freshwater fish make up more than half of the world’s known fish species, an incomprehensible diversity given that freshwater ecosystems make up only 1% of aquatic habitat. These diverse species are an integral part of the ecosystem, and essential to its resilience. This is essential for the billions of people who rely on freshwater ecosystems, and the millions of people who rely on their fisheries,” said Kathy Hughes, Co-Chair of the IUCN Species Survival Commission Freshwater Fish Specialist Group.

“Ensuring that freshwater ecosystems are well managed, remain free-flowing with sufficient water, and good water quality is essential to halt species decline and maintain food security, livelihoods and economies in a climate-resilient world,” she said.

Central South Pacific and East Pacific green turtles are also at risk of extinction, according to scientists. They are a major bycatch in industrial and artisanal fishing, while their eggs are a delicacy in some countries. Rising global temperatures also affect their hatching success and rising ocean temperatures flood nests.

• This article was amended on 11 December 2023. A previous version incorrectly described the hornet as the world’s fourth largest mammal – it is the fourth large animal to be successfully returned to the wild in the last 100 years.

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