Freshwater fish resources are threatened

In a recent report published in BioScience, scientists said that over-exploitation of freshwater fish is threatening the biodiversity of lakes and rivers on a global scale. It also seriously affects food supply and employment in developing countries.

" This is a real risk, " said Kirk Winemiller, a seafood researcher at the Texas Agricultural Experimental Station. " Currently, freshwater fishes are more at risk than saltwater fish ."

Among the rivers and lakes mentioned in the report are the Mekong River. This is home to giant Mekong catfish - the largest freshwater fish in the world (weighing up to 300kg, length of 2.7m), and many other big fish are threatened with extinction.

A number of other aquatic species are also at risk: Murray cod in the Murray River Basin (Australia) and sturgeon in the Great Lakes (North America).

Fishing in the world's rivers and lakes has quadrupled since 1950. Currently, the annual catch of freshwater fish is about 8.7 million tons, of which 2/3 is caught in Asia. .

Particularly in the Mekong basin, the average annual fish consumption is 56kg / person. Among the many fish caught, there are the largest and rarest fishes in the world, such as giant Mekong catfish, long-tailed freshwater flounder and sticklebacks.

Zeb Hogan - a fish researcher at the University of Wisconsin, Madison (USA), and a leading researcher of the National Geographic Society - said in recent years the chances of catching Mekong catfish have decreased. seeing, from 60 in 1995 to only 4 in 2005. He expressed concern that in just a short time this catfish breed will remain a myth.

The report also said that people have used many means to catch fish of different sizes. Starting from the largest category and gradually moving to smaller species leads to depletion of aquatic species.

"Big fish are a source of breeding - David Allan, Professor of Biological Conservation at the University of Michigan, one of the report's authors, said:" Fertility increases as fish size increases, so you The big one is especially important for the survival of the species ".

And when big fish become more and more rare, it is the turn of "small" fish. Queme River in Benin, West Africa has seen large carnivorous fish such as the Nile river bass being replaced by small fish such as cichlids and catfish.

According to the researchers, depleted fish stocks can cause serious impacts on human health, especially in developing countries.

For example, an increase in the prevalence of schistosomiasis in Africa is associated with a decline in fish species eating infected snails. Moreover, for tens of millions of poor residents of Asia and Africa, freshwater fish is one of the important sources of life.

Therefore, the preservation of this resource is extremely important for the survival of the poor.