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by Steve Atkinson
The Record
Feb. 28, 2007

In 2006 the BC Pacific Salmon Forum funded a variety of research initiatives. Many of these initiatives focused on wild/farmed fish interactions and sea lice.

Between 2004 and 2006 sampling was done on emigration rates of juvenile chum salmon. The samples were taken at multiple points in Clayoquot Sound on the West Coast of Vancouver Island and in the Broughton Archipelago. Rating was based on both before and after wild fish passed local salmon farms. It was found that low water salinity was associated with reduced sea lice abundance.

In studies farmed salmon were treated with SLICE (emamectin benzoate). This was done to see if it protects out-migrating juvenile salmon from sea lice transmission from farmed salmon. Studies found that the treatment has a significant impact in reducing sea lice levels.

In northern BC there are staging areas for pink smolts during the summer. Here they grow before leaving for their migration up the Pacific shelf waters to the Gulf of Alaska. These high prevalence zone areas are also the place where returning adult chinook stage before entering the rivers. The question was whether returning adult salmon are the source of many of the sea lice that appear in the pink salmon. In 2006 collected data was examined. It was found there was a sharp increase in the abundance of sea lice on the pink salmon smolts. However, the levels were very much lower seen in areas such as the Broughton Archipelago.

There have been laboratory studies on the factors influencing sea lice on salmon. It has been shown that Pacific salmon are much less susceptible to infection with the sea lice than are Atlantic salmon. However, sea lice biology and higher infestation intensities on the physiological impact of salmon need to be examined.

The complex relationships of wild and farmed salmon in the west coast environment are not yet fully understood. The findings will help direct future research. Summaries of the preliminary results of this research can be accessed at www.pacificsalmonforum.ca .

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