A new, first-of-its-kind comprehensive global report on the status of migratory freshwater fish reveals an alarming 76 percent drop in average populations between 1970 and 2016.
"The Living Planet Index (LPI) For Migratory Freshwater Fish", launched 28 July by the World Fish Migration Foundation and the Zoological Society of London observe that populations of salmon, trout, and Amazonian catfish, for example, are under immense threat from human-made impacts such as hydropower, overfishing, climate change, and pollution. The researchers call for urgent action to halt the current decline and to reverse the trends.
The data also shows a 93 percent decline in Europe and an 84 percent decline in Latin America and the Caribbean, higher than the rates of decline in terrestrial and marine species. The findings are based on information for 1,406 population of 247 species listed on the Global Register of Migratory Species.
Arjan Berkhuysen, Managing Director of the World Fish Migration Foundation said. “Catastrophic losses in migratory fish populations show we cannot continue destroying our rivers. This will have immense consequences for people and nature across the globe. We can and need to act now before these keystone species are lost for good".
The report attributes habitat degradation, alteration and loss to approximately 50 percent of the threats to migratory fish. Wetlands are essential habitats but are disappearing and dams and other river barriers block fish from mating and feeding grounds, thereby disrupting life cycles. Over-exploitation also is contributing to the decline.
Finally, populations are threatened by the impacts of climate change. Changes in river temperatures can trigger migration and reproduction, causing these events to happen at the wrong time. Misalignment of reproduction and lack of food in specific habitats are also contributing factors.
“Migratory fish provide food and livelihoods for millions of people but this is seldom factored into development decisions. Instead, their importance to economies and ecosystems continues to be overlooked and undervalued – and their populations continue to collapse,” said Stuart Orr, WWF Global Freshwater Lead. “The world needs to implement an Emergency Recovery Plan that will reverse the loss of migratory fish and all freshwater biodiversity – for the benefit of people and nature".
Dam removal is proving successful in improving habitat and biodiversity in rivers as has been demonstrated in the United States. This strategy is spreading to Europe.
“Rivers and migrations are the connective tissue of our planet – and migratory fish are bellwethers for not just rivers, but for the countless other systems they connect, from the deep sea to coastal forests. Losing these fish means losing so much more,” said Jeffrey Parrish, Global Managing Director for Protect Oceans, Land and Water at The Nature Conservancy. “By factoring in these species and systems into sustainable energy and food production, and by investing in their protection and restoration, we can bring them back".
The report and the organisations that have supported the research call upon the global community to protect free-flowing rivers and to guide basin-wide planning.
Implementing conservation initiatives and water protection laws, investing in sustainable renewable alternatives to hydropower and fostering public and political will lead to development of practical solutions to protect fish populations.