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1 in 4 freshwater species are at risk of extinction: "It's not too late to take action"

Researchers have studied over 23,000 freshwater species globally.

Salmon is classified as Near Threatened both on the IUCN Red List of Threatened Species, which assesses the risk of species extinction on a global scale, and on the Norwegian Red List for Species.
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Presented by: NINA - Norwegian Institute for Nature Research
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Although freshwater habitats like rivers, lakes, wetlands, and similar environments cover only one per cent of the Earth's surface, they are critical habitats for wildlife. They are home to 10 per cent of all known species and provide vital ecosystem services.

Since 1975, 35 per cent of the world’s wetlands have been lost, and the decline continues. This has dramatic consequences for biodiversity.

Not too late to take action

In a new study, researchers have compiled global assessments and IUCN Red List data for freshwater fish, dragonflies, and crustaceans. 

The results show that nearly a quarter of freshwater wildlife is at risk of extinction. The main threats include pollution, dams, agriculture, and invasive species.

Researcher Eva B. Thorstad from the Norwegian Institute for Nature Research (NINA) is one of the experts behind the study. She is also regional co-chair of the IUCN Salmonid Specialist Group, which assesses the extinction risk of species globally.

“This study highlights a serious challenge, but it’s not too late to take action,” says Thorstad.

This research provides a knowledge base for developing strategies, political decisions, and priorities both nationally and locally to halt biodiversity loss.

The study is the largest risk assessment of freshwater wildlife to date, requiring an enormous effort to compile. Each species has been carefully evaluated by experts from several countries, and this information forms the basis for the Red List assessments. 

More than 1,000 researchers have contributed data, and it has taken 20 years to create this comprehensive overview.

What is the situation in Norway?

Compared to many other parts of the world, Norway has relatively few freshwater species. According to the Norwegian Red List, most of Norway’s 45 freshwater fish species are classified as Least Concern.

However, even if the species themselves are not directly threatened, freshwater habitats in Norway are highly affected. Most large rivers are regulated or otherwise impacted by human activity. 

Additionally, pollution, invasive species, and climate change pose challenges. Combined, these factors could have major consequences if not addressed.

“Norway has abundant clean water, which is quite unique globally. This is a resource we must protect. We have the necessary knowledge to safeguard freshwater biodiversity and can implement targeted measures to ensure sustainable management and conservation where needed,” says Thorstad.

Norwegian Red List for Species

The noble crayfish is one of the species classified as Critically Endangered on the Norwegian Red List. Several dragonfly species are also listed as Near Threatened or Vulnerable.

European eels spawn in the Sargasso Sea and are carried by ocean currents to the coastal areas of Europe and North Africa. Here, the eel lives near the coast or migrates to freshwater, where it remains until it reaches sexual maturity.

Fish species that migrate between freshwater and the sea are particularly at risk, with most of these species appearing on the Norwegian Red List. 

The eel is Critically Endangered, while salmon and sea lamprey are Near Threatened. 

These species face threats both in rivers and the sea that affect their survival and reproduction. Despite facing similar challenges, different management approaches are required.

“Salmon begin their lives in rivers, migrate to the ocean to grow, and then return to the same river to spawn," says Thorstad.

Here, local and regional measures can be implemented to improve conditions for salmon.

“The eel, however, has the opposite life cycle, with all individuals spawning in the same marine area. The eel is therefore more dependent on international management and cross-border cooperation than salmon, as the European eel constitutes one shared population,” she says. 

Reference:

Sayer et al. One-quarter of freshwater fauna threatened with extinction, Nature, 2025. DOI: 10.1038/s41586-024-08375-z

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