The report comes from researchers with Sea Around Us, an initiative at the University of British Columbia’s Institute for the Oceans and Fisheries and the University of Western Australia.
The paper, “Global marine fisheries discards: a synthesis of reconstructed data,” was published on June 26 in the journal Fish & Fisheries, online at http://onlinelibrary.wiley.com/doi/10.1111/faf.12233/full
The loss of good fish is equivalent to throwing back enough fish to fill about 4,500 Olympic sized swimming pools every year, the report said.
“While indeed discard mortality rates vary by location, species and gear type used, our numbers are all dead discards,” said Dirk Zeller, a professor of marine conservation with the University of Western Australia’s School of Biological Sciences, in response to an email query.
In cases such as the United States, where total discard rates as well as discard mortality rates are known, we take this into account, but the US is an exception, and for most countries and thus most fisheries, this is not known, recorded or studied, Zeller said.
Given that the researchers only estimate major discards in each country, and thus are missing discards from many other gear types in each country, our discard estimates are conservative, he said.
Given the current era of increasing food insecurity and human nutritional health concerns, these findings are important, said Zeller, lead author for the study and senior research partner with the Sea Around Us. “The discarded fish could have been put to better use.”
Zeller and his colleagues Tim Cashion, Maria Palomares and Daniel Pauly said they study also showed how industrial fleets move to new waters once certain fisheries decline.
“The shift of discards from Atlantic to Pacific waters shows a dangerous trend in fisheries of exporting our fishing needs and fishing problems to new areas, Cashion said.
While the study showed a decline in discards in recent years that could be attributed to improved fisheries management and new technology, Zeller and his colleagues say it’s likely also an indicator of depleted fish stocks.
“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,” Zeller said.