New fish farm study cites crash in salmon, trout populations
In a development that promises to further rattle the credibility of provincial aquaculture policy, a new study by scientists at Nova Scotia’s Dalhousie University reports that fish farms are directly associated with plummeting populations of wild salmon and trout.
On average, the paper says, survival and abundance of wild salmon and trout crashed by 50 per cent or more in areas where fish farms were established.
“Many of the salmon populations we investigated are at dramatically reduced abundance, and reducing threats to them is necessary for their survival. Reducing impacts of salmon farming on wild salmon should be a high priority,” the paper says, otherwise survival rates will fall even further as aquaculture increases.
Agriculture and Lands Minister Pat Bell, whose government lifted a moratorium on fish farm expansion and has since overseen rapid growth in the industry, recently said B.C. salmon farmers do a good job in protecting the environment and controlling parasites that prey on immature wild salmon.
The paper, A Global Assessment of Salmon Aquaculture Impacts on Wild Salmonids, written by Jennifer Ford and Ransom Myers, was published today by the Public Library of Science Biology, an international peer-reviewed journal.
The scientists compared the marine survival of wild salmon and trout populations in areas with fish farms with similar populations in adjacent areas without farms. Conditions in Scotland, Ireland, Atlantic Canada and the B.C. coast were examined and compared to determine correlations between wild salmon survival rates and the growth of salmon farming.
In B.C., coho, pink and chum stocks were studied in Johnstone Strait where fish farms are concentrated in narrow inlets and passages, then compared with control populations on the undeveloped central coast.
“We show a reduction in survival or abundance of Atlantic salmon; sea trout; and pink, chum and coho salmon in association with increased production of farmed salmon. In many cases, these reductions in survival or abundance are greater than 50 per cent,” the authors conclude.
Along with Martin Krkosek, a University of Alberta scientist, and Alexandra Morton, a biologist from Simoom Sound, Ford and Myers wrote an earlier paper that predicted the extinction of wild salmon runs in B.C.‘s Broughton Archipelago in four years if steps were not rapidly taken to control sea lice infestations. Advocates for B.C.‘s aquaculture industry have long argued that farming salmon protects wild stocks by reducing commercial fishing pressure, and that sea lice associated with net pen aquaculture are not detrimental to migrating salmon smolts.
The new paper seems certain to trigger a new storm of controversy. It comes just as the salmon forum—established by Premier Gordon Campbell to oversee research to determine whether fish farms are a threat to wild salmon and steelhead stocks—releases an interim report that claims: “In the context of the 2007 interim research results it does not appear that the natural stocks of pink salmon in the Broughton would be subjected to mass extinctions within four generations as predicted by the recent study by Martin Krkosek.”
Furthermore, a paper soon to be published in Reviews in Fisheries Science by Kenneth Brooks, a scientist who does research for aquaculture clients, challenges Krkosek’s methodology and conclusions.
However, a communique released last week by John Fraser, the former speaker of the House of Commons who chairs the salmon forum, appears to suggest that the paper by Krkosek and Morton has scientific merit.
It said that in a recent meeting to discuss their paper: “There was general acknowledgement that . . . sea lice infestations between 2001 and 2005 likely contributed to depressed productivity of pink salmon in the Broughton Archipelago. There was general agreement that the paper’s predictions regarding extinction are dependent on future management regimes.”
Now, there’s an opening for the provincial government. If closed containment isn’t yet an economically viable option for fish farms, allowing them to put wild salmon stocks worth more than a billion dollars a year at risk isn’t viable, either.
Perhaps prudent “future management” might consider either fallowing all farms on migration routes while immature wild fish are present, or relocating farms away from sensitive estuaries and migration routes.
shume@islandnet.com