By Lewis Smith
Almost one in ten of every fish caught is dumped back into the ocean dead or dying, researchers have warned.
Industrial fishing fleets are most to blame for almost 10 million tonnes of fish being discarded every year, say scientists.
A number of factors are behind the problem, including that of the “nasty practice” of high-grading — dumping a hold full of one type of fish to make way for a more lucrative catch.
Other reasons for dumping freshly-caught fish include damage caused while hauling them on board the boat, being too small or being netted when the species is out of season.
Researchers behind the study also identified historical levels of discarding. They found that in the 1950s five million tonnes were dumped annually, rising to a high of 18.8 million tonnes in the late 1980s.
The quantity has fallen in recent years to just under 10 million tonnes and the reason is in part down to improved practices by the fishing industry but scientists said it is also because fish are more scarce and thus fewer can be caught.
“Discards are now declining because we have already fished these species down so much that fishing operations are catching less and less each year, and therefore there’s less for them to throw away,” said Professor Dirk Zeller, the lead author of the study.
He said that the finding had implications for feeding the rising world human population: “In the current era of increasing food insecurity and human nutritional health concerns, these findings are important. The discarded fish could have been put to better use.”
Professor Zeller, of the University of Western Australia, was particularly concerned at the continuing practice among some fishermen of dumping a catch simply to increase their profits.
“Discards also happen because of a nasty practice known as high-grading where fishers continue fishing even after they’ve caught fish that they can sell,” he said. “If they catch bigger fish, they throw away the smaller ones; they usually can’t keep both loads because they run out of freezer space or go over their quota.”
Tim Glover, managing director of Fish2fork, a marine campaign group, said the level of discards was “unacceptable and disgraceful”.
He said: “There can be no justification for such wasteful behaviour that empties the seas. Fish stocks are a finite resource - not a magic porridge pot that never empties.”
The study by Professor Zeller with colleagues from the
Sea Around Us project at the University of British Columbia in Canada, was published in the journal Fish & Fisheries and found that discarding was worst in the North Atlantic Ocean until the 1980s and that today practices in the western Pacific are the most reprehensible. Poor practices and poor regulation of the fisheries was cited.
Indonesia, Thailand, Spain, the US, Russia Japan and China were named as being among the worst for discarding.
“Russia dominates discarding in the Northwest Pacific, accounting for over 50 per cent in recent decades, on average, with Japan and South Korea (mainly in earlier decades), and more recently China also contributing substantially,” the study said.
It mostly takes place within 200 mile limits but in recent years the proportion taking place in the high seas, international waters, has risen from 1 to 6 per cent.
Haddock was the most discarded fish in the North East Atlantic, with 19 per cent of the catch dumped, followed by redfish on 16 per cent, Atlantic cod on 11 per cent and hake with 6 per cent.
Researchers added: “The latest major development is the expansion of fishing fleets in the Northwest Pacific mainly for Alaska pollock, resulting in substantial discards of this target species, especially in Russian waters, where the fleets tend to land only the roe of Alaska pollock.”
Photo: cod are among the fish that have suffered most from discards.