Temps de lecture :2 minutes
The over-harvesting of small fish to feed farmed salmon is threatening marine ecosystems worldwide, according to a report commissioned by respected environmental organisations. Nonsense, say industry experts, the fisheries are well managed. So who is right?
Feed for farmed fish consists of up to 80 per cent fishmeal and oil, because predatory fish such as salmon need high levels of certain oils and proteins for rapid growth and the right taste. The report, done for the conservation group WWF, the Scottish Wildlife Trust and the UK’s Royal Society for the Protection of Birds (RSPB), claims many of the feed fisheries are not sustainable. It focuses on the fishmeal used by Scottish salmon farms, but many fish farmers worldwide rely on the same sources.
“Aquaculture can’t just keep on expanding without any measures of sustainability,” says Rebecca Boyd of WWF. “We’ll just end up plundering the ocean, and that means losing all round.” She says fish farmers should switch to sources of fishmeal that have been certified as sustainable by the Marine Stewardship Council.
The report singles out blue whiting, which accounts for 7 per cent of the global production of fishmeal and oil, as a particular worry. The North East Atlantic Fisheries Commission suggested a quota of 650,000 tonnes, but the policy was never implemented. In 2003 the catch exceeded 2.3 million tonnes. Whiting should not be used until it is properly managed, says Kate Brydson of the RSPB.
However, Henrick Sparholt, a fisheries assessment scientist at the International Council for the Exploration of the Sea, says that blue whiting numbers are higher than ever. The health of the population is somewhat mysterious, he concedes, and the species probably cannot withstand this level of catch for much longer.
The fishery for horse mackerel is another described as unsustainable by the report. But according to Sparholt, this species is not being overfished. In fact, most European fisheries used to make fishmeal and oil are well managed, he says.
Stuart Barlow, director of the industry group the International Fishmeal and Fish Oil Organisation, says feed producers are keen to protect fisheries. They are supporting an eco-labelling scheme for farmed fish being developed by UN’s Food and Agriculture Organization, he says.
But even critics of the report concede that meeting future demand for feed for farmed fish could be a problem if the aquaculture industry continues to grow rapidly. Researchers are trying to develop plant-based sources to reduce the need for fishmeal, which would also help reduce levels of pollutants such as PCBs in farmed fish (New Scientist, 17 January, p 8), but plant-based feeds are unlikely to replace fishmeal in the foreseeable future.
, issue 2467, 2 october 2004