Researchers have studied over 23,000 freshwater species from around the world. The conclusion is that nearly one quarter of freshwater animals are at risk of extinction.
Salmon is classified as Near Threatened (NT) 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. Photo: Eva B. Thorstad
Even though freshwater habitats like rivers, lakes, wetlands, and similar environments only cover 1% of the Earth's surface, they are critical habitats for wildlife. These ecosystems are home to 10% of all known species and provide us with essential ecosystem services.
Since 1975, 35% of the world’s wetlands have been lost, and continue to decline, with dramatic consequences for biodiversity.
In a new study, researchers have compiled global assessments and IUCN Red List data for freshwater fish, dragonflies, and crustaceans. The results reveal that nearly a quarter of freshwater wildlife is at risk of extinction. The main threats include pollution, dams, agriculture, and invasive species.
Eva B. Thorstad, researcher at NINA (Norwegian Institute for Nature Research), is one of the experts behind the study. She is also regional co-chair the IUCN Salmonid Specialist Group, assessing extinction risk for species globally.
“This study highlights a serious challenge, but it’s not too late to take action,” Thorstad says.
“This provides a knowledge base for developing strategies, political decisions, and priorities both nationally and locally to halt biodiversity loss.”
This is the largest risk assessment of freshwater fauna to date, requiring an enormous effort to compile. Each species has been carefully evaluated by experts from several countries, and the combined data underpins the Red List assessment. More than 1,000 researchers have contributed with data, and it has taken 20 years to create this 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, while the species themselves may not be 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 near threatened or vulnerable.
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.
What these species have in common is that they face threats both in rivers and at sea that affect their survival and reproduction. Despite the similar challenges, different management approaches are required.
“Salmon begin their lives in rivers, migrate to the ocean to feed grow, and then return to the same river to spawn. Here, we can implement local and regional management measures to improve conditions for salmon,” explains Thorstad. “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.”
Read the article in Nature: One-quarter of freshwater fauna threatened with extinction
Press release from IUCN Red List: One quarter of freshwater animals at risk of extinction - IUCN Red List
Contact: Eva B. Thorstad