Fraser River sockeye salmon: data synthesis and cumulative impacts

Kent: (…?) parasite mortality in coho that spans many rivers. Of all the pathogens, Parvicapsulaseems the one to look at in the interim. It is a widespread pathogen and there is normally alow intensity of infection, unless something has shifted. Temperature really drives these, sojust a few degrees change in ocean temperature can change these to pathogenic.Marmorek: It would be interesting to take McKinnell’s ocean temperature data and compare it tothe thresholds for these parasites.Kent: There are high levels of parasites in freshwater and the fish are leaving with those so theycould theoretically die in sea water. For Parvicapsula, one study found a high level infreshwater and then they didn’t see it in the marine environment, but it needs more studyHinch: We’ve done a lot of work on Parvicapsula. We don’t see it in the kidneys in adults. It’seither turned on or re-acquired. Some years we see strong disease and temperaturecorrelations, including Parvicapsula. We should also distinguish between en route and prespawningmortality, which are treated distinctly in Canadian management.Ashley: Was whirling disease introduced or did eutrophication amplify existing levels.Kent: This is an endemic pathogen, so land use activities on the Klamath River intensified anendemic disease. Snails are also vectors for human disease so there has been lots of work onthe effects of land use practices on snails and parasites.Ashley: The message to Cohen regarding watershed management is that these are principles youshould do anyway, but they have been ignored by agriculture.Kent: It was very difficult to tie land use practices to pathogen burdens as you need to show itacross multiple rivers. There are two mechanisms: directly increasing temperature andincreasing invertebrate hosts important for disease transmission.Staley: How will you deal with Kristi Miller’s work?Kent: I’m meeting her next week. We looked and didn’t see brain lesions. We don’t think theevidence is as strong of a pathogenic virus that killed the fish. Can I quote her with herpermission in my report?Levy: Yes.Hinch: Miller has a paper on this about to be published in a journal.Potential effects of contaminantsDon MacDonaldThis project included preparing an inventory of aquatic contaminants in the Fraser River inrelation to the distribution of sockeye CUs, comparing water quality in the Fraser to toxicity datafor Fraser sockeye, assessing the contaminants and natural substances encountered by juvenileand adult sockeye, and evaluating the extent to which reductions in sockeye abundance areassociated with contaminant conditions in the river.Approach: An ecological risk-based approach was used to identify where and when sockeye areexposed to contaminants, which ones they could be exposed to in their life cycle and a44