In an alarming but true scenario, the world's populations of migratory freshwater fish are in trouble, and much of it is humankind's fault. Our mining of raw materials, the pollution from our industries, and even our dams manipulating the natural flow of rivers have all negatively impacted ecosystems around the world.
What's happening?
According to a recent report by the Guardian detailing an update to the Living Planet Index, the population levels of freshwater fish have dropped by more than 80% since 1970. The most significant region of decline is in South America and the Caribbean, where biodiversity among fish species has plummeted by 91% over the past 50 years.
Human-made dams created either to reshape waterways or harness flows for hydroelectric power have disrupted the ecosystems for many creatures, especially fish. Industrial pollution and wastewater runoffs have further sullied these natural habitats, and overfishing in some areas can take its toll on fish populations.
Even climate change impacts migratory fish. Low water levels, unexpected seasonal shifts, and seawater encroaching on freshwater systems have a negative impact, an earlier Guardian report showed.
Why is this issue so important?
Migratory fish rely on freshwater systems for all or part of their lives. Some are born in the ocean and move into freshwater. Others may be born in freshwater and migrate to the ocean later in life. Keeping these waterways open is key to their survival.
Herman Wanningen, founder of the World Fish Migration Foundation, said in a press release on behalf of several organizations including her foundation: "Migratory fish are central to the cultures of many Indigenous peoples, nourish millions of people across the globe, and sustain a vast web of species and ecosystems. We cannot continue to let them slip silently away."
What's being done about this shocking decline?
Overfishing can be regulated, and setting aside "no fishing zones" has already been shown to work, with fish populations rebounding after the plans were in place. And with record-breaking progress in solar and wind generation, supplying grid demands and saving costs to consumers, we have viable alternatives to new hydroelectric dam developments.
Although there are an estimated 1.2 million barriers across European rivers, there's a push to reverse that blockage. According to the World Fish Migration Foundation's report, a record 487 waterway barriers were removed last year across 15 European countries. Dam removal projects are seeing increased support, and there appears to be some momentum in 2024.
Michele Thieme, deputy director of freshwater for the World Wide Fund for Nature U.S., said in the release: "We have the tools, ambition, and commitment to reverse the collapse of freshwater fish populations … Prioritizing river protection, restoration, and connectivity is key to safeguarding these species."
Wanningen provided a strong salvo, saying: "The catastrophic decline in migratory fish populations is a deafening wake-up call for the world. We must act now to save these keystone species and their rivers."
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