Impacts of aquaculture on wild salmon are one the most contentious issues on the coast of western Canada.
I am working with graduate students who are studying fish farms as sources of sea lice on wild juvenile salmon. We have found that when wild fish swim past open net pen fish farms in several regions of BC, they have strongly elevated parasite loads. A peer-reviewed paper on pink and chum salmon is here, and a reply to a rebuttal from DFO is here! Another paper on sockeye salmon is here.
More recently (2015), we have published a paper showing that “lousy fish are lousy competitors”. That is, juvenile sockeye salmon that are heavily infected with sea lice are 20% less effective at foraging when in competition with lightly infected fish. This suggests that sea lice may reduce growth and survival of these fish. Our paper is here.
I was also part of a team who published a paper in 2012 showing that the decline of many sockeye salmon populations over the past 20 years has been due to a combination of exposure to salmon farms, elevated sea temperatures, and competition with Pink salmon in the north. While none of these factors can explain the sockeye declines on their own, the combination of the three has created a perfect storm, probably due to the weakened condition of juvenile sockeye that have caught diseases when migrating past salmon farms, and then being less able to deal with warm temperatures and competition with Pink salmon. The report is here, and the cover photo from the journal is here.
I have served on the Science Advisory Committee of the BC Pacific Salmon Forum, which was appointed by the Premier of the province to investigate impacts of aquaculture and other human activities on sustainability of wild salmon. The Final Report makes a strong case for more coherent watershed-level governance.
I also worked with the Cohen Commission’s judicial enquiry into declining sockeye salmon from the Fraser River watershed, as an expert witness and as a reviewer of three of their technical reports. Their final report was released on September 30th, 2012. We are still waiting for a response by the federal government to the report’s 75 recommendations. To help, a group of us had a 2-day think tank at SFU in February 2013, followed by a public session where we presented our our views on the top priorities. You can see our report here.