Bottom trawling causes deep-sea fish populations collapse

Date: April 12, 2018

Source: PhysOrg 
Author: Sea Around Us

A new study using the Sea Around Us‘ reconstructed catch data reveals that in the past 60+ years, the practice of towing giant fishing nets along the sea floor has caused the extraction of 25 million tonnes of fish that live 400 metres or more below sea level leading to the collapse of many of those fish populations.

The new estimates suggest that 42 per cent more fish have been caught by countries than they reported to the Food and Agriculture Organization of the United Nations. “Our study shows that there is systematic under-reporting of the real catch. This means that fisheries managers are making decisions based on incorrect data, which has dramatic consequences for marine ecosystems,” said Lissette Victorero, lead author of the paper and a Ph.D. student at the National Oceanography Centre in the United Kingdom.

The study, which was published today in Frontiers in Marine Science, examines the state of 72 deep-sea fish species caught by bottom trawlers around the world, many of which were exploited to unsustainable levels.

For example, Roundnose grenadier estimated catches were greater than 60,000 tonnes in 2001 in the Northeastern Atlantic, but the stock was overfished so fast that a moratorium had to be imposed in 2006 in Norwegian waters. “One of the reasons behind this collapse is the fact that trawls are not selective, that is, they catch everything and anything, which means that young grenadiers that have not yet reached full reproductive development are caught along with adult grenadiers, decreasing the ability of the population to recover,” said Deng Palomares, co-author of the study and the Sea Around Us Project Manager at the University of British Columbia.

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