China has been catching more than 12 times the amount of fish it has been reporting to the United Nations, according to a new study in Fish and Fisheries, more than half of it–2.9 million tons–from off the coast of West Africa. Nature reports that this could explain some fishy declines in countries like Mauritania:
Fisheries scientists find the latest assessment startling. “So that’s where my fish were going!” says Didier Gascuel at the European University of Brittany in Rennes, France, who is a member of the scientific committee that advises Mauritania and the European Union on fishing agreements. Year after year, Mauritanian populations of bottom-dwelling species such as octopus, grouper, and sea bream have remained stubbornly low–a sign of overfishing by bottom-scraping trawlers, he says. “We had no idea the Chinese catch was so big and of course we never included it our models,” he says.
On the other hand, this is just one study, involving a considerable amount of guesswork. The scientists first estimated the number of Chinese vessels by using clues from “field interviews, scholarly articles, and newspaper and online reports in 14 languages” and then multiplied that number by an assumed catch per vessel.
Other experts are sceptical. “The new estimates seem far, far too high,” says Richard Grainger, chief of the fisheries statistics and information service at the UN’s Food and Agriculture Organization. He notes that a previous assessment estimated the total unreported catch off West Africa (by all nations) at 300,000 to 560,000 tonnes a year. That study tried to identify what was missing from official catch figures with a review of English-language scientific studies.
If the new figures are accurate, Nature reports, it could force other countries to reduce their catch to avoid population collapse.