Migratory freshwater fish, such as trouts, salmons or Amazon catfishes, have decreased their populations by 76% worldwide and 93% in Europe during the last fifty years as a result of habitat fragmentation, overfishing, climate change and pollution.
These are the main conclusions reached in the first global report on the state of these species, published by the World Fish Migration Foundation and the Zoological Society of London. These migratory fish species are critical to meet the needs of food security and play a key role in river, lake and wetland maintenance.
The report points out that habitat degradation and loss is the main factor causing the decline of migratory freshwater fish, followed by unsustainable fishing and bycatch, and the effects of the climate crisis.
Wetlands are disappearing three times faster than forests. Dams and other river barriers disrupt the life cycles of migratory fish, unable to reach mating or feeding areas. Temperature changes also trigger biological processes in species living in a specific habitat, such as reproduction, during those periods in which food is no longer available.
The value of migratory fish
Migratory fish provide many ecosystem services, including food and work for millions of people, but this is rarely taken into account and many countries do not take action on preserving them. In this scenario, it’s necessary to implement an emergency recovery plan reversing the current trend of biodiversity loss in the best interest of people and nature. We still have a chance to turn the tide by finding practical solutions to protect migratory fish. The international community must intervene to redesign river planning implementing conservation measures and investing in alternative large hydraulic infrastructures. We’re facing an unprecedented decline and policy-makers must act to save these species before reaching a point of no-return.