You want to know if they have been examined in connection with the general decline of salmon populations in British Columbia. As far as shipping traffic goes, I don't think so, not with regard to salmon, but people do look at shipping traffic for effects, particularly on killer whales and other cetaceans that hunt by sound. That can interfere with their communication with each other and locating prey.
Pollution can have a very large effect on ecosystem dynamics. It can change the productivity and ecology of the plankton, which has ramifications for everything above the plankton in an ecosystem. There are multiple sources of pollution, usually associated with industry and large human populations, but also with the waste material that comes from the salmon farms. That addition of nutrients to an ecosystem can change the dynamics of the plankton, which can have implications. But as far as I know, there is no detailed work looking at that.