A new update to the IUCN Red List of Threatened Species has revealed that 25% of freshwater fish are at risk of extinction, and at least 17% of threatened freshwater fish species globally are affected by climate change. IUCN (International Union for Conservation of Nature) is the world’s largest and most diverse environmental network, and a global authority on the status of the natural world and the measures needed to safeguard it.
The update, released at the ongoing COP28 UN climate conference in the United Arab Emirates, also highlights the impact of illegal logging and trade on mahogany.
According to an IUCN press statement released on Monday, the IUCN Red List now includes 157,190 species, of which 44,016 are threatened with extinction. “Climate change is menacing the diversity of life our planet harbours, and undermining nature’s capacity to meet basic human needs,” Dr Grethel Aguilar, IUCN director general, said in the release. “This IUCN Red List update highlights the strong links between the climate and biodiversity crises, which must be tackled jointly. Species declines are an example of the havoc being wreaked by climate change, which we have the power to stop with urgent, ambitious action to keep warming below 1.5 degrees Celsius.”
According to IUCN, the new update completes the first comprehensive assessment of the world’s freshwater fish species, revealing that 25% (3,086 out of 14,898 assessed species) are at risk of extinction. At least 17% of threatened freshwater fish species are affected by climate change, including decreasing water levels, rising sea levels causing seawater to move up rivers, and shifting seasons. This compounds threats from pollution, which impacts 57% of freshwater fish species at risk of extinction, dams and water extraction, which affect 45%, overfishing, which threatens 25%, and invasive species and disease, which harm 33%, the release said.
One example is the large-toothed Lake Turkana robber (Brycinus ferox) – an economically important species endemic to Kenya – that has moved from ‘Least Concern’ to ‘Vulnerable’ on the IUCN Red List, due to overfishing, climate-change driven habitat degradation and dams reducing freshwater entering the lake.
Another example of the freshwater fish species at risk is the Atlantic salmon (Salmo salar). According to IUCN, the species has moved from ‘Least Concern’ to ‘Near Threatened’, with new evidence showing the global population decreased by 23% between 2006 and 2020. Atlantic salmon are now restricted to a small portion of the rivers they inhabited a century ago across northern Europe and North America, due to multiple threats over the course of their long-distance migrations between freshwater and marine habitats, the release explains. “Climate change affects all stages of the Atlantic salmon’s life cycle, influencing the development of young salmon, reducing prey availability and allowing invasive alien species to expand their range,” the release adds.
The update also revealed that the Central South Pacific and East Pacific green turtle (Chelonia mydas) populations are respectively ‘Endangered’ and ‘Vulnerable’ to extinction. Climate change has affected the species in multiple ways. “High temperatures result in lower hatching success, rising sea levels threaten to flood nests and drown the young, and the seagrasses that green turtles eat are susceptible to ocean warming and changes in currents due to extreme weather,” the release said.
There were, however, some success stories, as the update revealed that conservation efforts have successfully brought two antelope species (the scimitar-horned oryx and the saiga antelope) back from the brink of extinction but changing climatic conditions could undermine their future.
“The climate and biodiversity crises are two sides of the same coin. On the one hand, climate change is one of the drivers of documented declines in animals, fungi and plants, but on the other, the resilience of nature through recovery and regeneration of species and ecosystems is our most powerful ally to combat accumulation of greenhouse gases in the atmosphere,” Dr Jon Paul Rodríguez, chair of the IUCN Species Survival Commission, said in the release. “This Red List update illustrates both the climate-related mechanisms behind declines of fishes and sea turtles, as well as the recovery of scimitar-horned oryx and saiga through proactive conservation action.”