Freshwater fish faces a group of threats that push many species toward extinction. The International Union for Conservation of Nature (IUCN) conducted a global assessment to compile the Red List of threatened species for the first time, highlighting the urgent risks facing these waterside residents.
Within the framework of the Dubai climate summit COP28, the IUCN released an updated Red List that now includes 157,190 species, with 44,016 of them (28%) classified as threatened. This represents an increase of more than 2,000 species compared with the previous review, underscoring a growing biodiversity crisis. The update emphasizes the intertwined nature of climate change and biodiversity loss and calls for integrated action to address both challenges.
IUCN Director General Grethel Aguilar warned that the decline of species illustrates the damage caused by warming and stressed the strong links between climate and biodiversity crises. The call is clear: climate policy and wildlife conservation must be pursued in tandem to preserve ecosystems and the services they provide.
What threatens fish?
The world’s most comprehensive assessment of freshwater fish reveals that 3,086 species, or 25% of the 14,898 evaluated, are at risk of extinction. The pandemic has had a broad impact, affecting at least 17% of these species globally. Key drivers include climate-driven changes in river flows, saltwater intrusion into freshwater systems, and shifts in seasonal patterns that disrupt life cycles.
Fish populations are also being harmed by pollution, habitat fragmentation, and altered water regimes. Dams, water extraction, and habitat degradation account for a large share of threats, while overfishing and the spread of invasive species and diseases contribute significantly to declines.
Freshwater fish constitute more than half of all known fish species. Kathy Hughes, co-chair of the IUCN/SSC Freshwater Fish Specialist Group, highlights that freshwater ecosystems offer astonishing diversity even though they occupy a mere 1% of the world’s aquatic habitat, delivering essential resilience to aquatic and terrestrial ecosystems alike. Efficient management and sustained water quality are crucial to halting species decline and safeguarding food security, livelihoods, and economic stability.
Maintaining healthy freshwater ecosystems with reliable water flow is essential. Protecting these habitats supports not only biodiversity but also human communities that depend on fisheries and clean water for nutrition and livelihoods.
Atlantic salmon case
Among the species studied, Atlantic salmon has shifted from a status of least concern to near threatened. Populations declined by about 23% between 2006 and 2020 due to multiple pressures during migration between seas and rivers. Today, their range is limited to a small fraction of the rivers once inhabited in Northern Europe and North America.
Atlantic salmon face challenges at every life stage. Climate change alters ocean and river conditions, reduces prey availability, and enables invasive species to expand. Dams and other barriers block access to spawning and feeding grounds, while water pollution and sedimentation from logging and agriculture increase juvenile mortality. Escapes from fish farms also threaten wild stocks, compounding the risk of decline.
In a broader sense, warming temperatures threaten many sea turtle populations as well. The Central South Pacific and Eastern Pacific green turtles (Chelonia mydas) confront higher nest temperatures that lower hatching success, rising sea levels that flood nests, and the loss of seagrass meadows critical for feeding. These combined pressures threaten long-term survival of the species.
Success Stories
The report also documents conservation successes. The scimitar-horned oryx (oryx) has moved from extinct in the wild to endangered thanks to reintroduction efforts in Chad. The saiga antelope population, once critically endangered across regions including Kazakhstan, Mongolia, Russia, and Uzbekistan, has rebounded to near threatened as measures help stabilize numbers.
Mahogany is in danger
The IUCN lists big leaf mahogany (Swietenia macrophylla) as endangered after previously being classified as vulnerable. New research shows a dramatic 60% reduction in its global presence over the last 180 years, driven by unsustainable logging and encroachment of tropical forests in Central and South America. The wood remains highly valued in the United States, Western Europe, and China for high-quality furniture, plywood, decorative items, and musical instruments.
Although protected by laws and ongoing conservation work, illegal logging and trade persist due to persistent demand. The continued pressure on mahogany highlights the tension between economic interests and biodiversity preservation, underlining the need for stronger enforcement, sustainable harvesting, and forest restoration to safeguard these iconic trees.