Freshwater Fish Population Is On The Decline Thanks To Us & Globally They Are Facing Extinction

Around the world, the population of freshwater fish is on the decline and we humans are to be blamed for it.

A recent study of almost 2,500 rivers around the world showed that human activity has endangered freshwater fish biodiversity in significant ways in more than half of the researched waterways. The study stated that around 23% of freshwater fish species are under the threat of extinction due to these circumstances.

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The study, titled 'Human impacts on global freshwater fish biodiversity' was published in the journal ¡°Science,¡±

Grim readings

According to the study, only 14% of the world's rivers and their fish populations remained unaffected, at least to a major degree.

The study revealed that the remaining 86% of the world's rivers have been heavily damaged from fragmentation, the introduction of non-native species and industrialization. Most of the rivers suffered from homogenization, which led to them housing increasingly fewer specialized lineages and similar species, reducing biodiversity.

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Excessive fishing

The most impactful human activities have been excessive fishing, the interruption of the natural flow of rivers due to dams, inter-basin transfers and water withdrawal, increases in invasive species and climate change.

170 fish species of the total 10,682 examined in the study are thought to have gone extinct. The worst affected areas were large, populous and wealthy regions like western Europe and North America. One particular example included the River Thames in London. The study adds to existing research that humans drive a 70% decline in animal species and caused 60% of the population to be wiped out in 44 years with their activities.

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A separate report, titled World¡¯s Forgotten Fishes published by WWF and 15 global conservation organizations have painted a similar picture.

Freshwater biodiversity declining fast

Freshwater biodiversity is declining at twice the rate of that in our oceans or forests. Indeed, 80 species of freshwater fish have already been declared ¡®Extinct¡¯ by the IUCN Red List of Threatened Species, including 16 in 2020 alone. Meanwhile, populations of migratory freshwater fish have fallen by 76 per cent since 1970 and mega-fish by a catastrophic 94 per cent.

¡°Nowhere is the world¡¯s nature crisis more acute than in our rivers, lakes and wetlands, and the clearest indicator of the damage we are doing is the rapid decline in freshwater fish populations. They are the aquatic version of the canary in the coalmine, and we must heed the warning,¡± said Stuart Orr, WWF global Freshwater Lead. ¡°Despite their importance to local communities and indigenous people across the globe, freshwater fish are invariably forgotten and not factored into development decisions about hydropower dams or water use or building on floodplains. Freshwater fish matter to the health of people and the freshwater ecosystems that all people and all life on land depend on. It¡¯s time we remembered that.¡±

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The report highlights the devastating combination of threats facing freshwater ecosystems ¨C and the fishes that live in them ¨C including habitat destruction, hydropower dams on free flowing rivers, over abstraction of water for irrigation, and domestic, agricultural and industrial pollution. In addition, freshwater fishes are also at risk from overfishing and destructive fishing practices, the introduction of invasive non-native species and the impacts of climate change as well as unsustainable sand mining and wildlife crime.

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For example:

The hilsa fishery in the Ganges upstream of Farakka crashed from a yield of 19 tonnes to just 1 tonne per year after the construction of the Farakka barrage in the 1970s

Poaching for illegal caviar is a key reason why sturgeons are one of the world¡¯s most threatened animal families, while Critically Endangered European eels are the most trafficked animal.

Excessively high fishing quotas in Russia's Amur river contributed to a catastrophic fall in the country¡¯s largest salmon run with no chum salmon found in spawning grounds in summer 2019.