Salmon Steward is the official publication of the Pacific Salmon Foundation in British Columbia, Canada
Issue link: http://digital.canadawide.com/i/1182504
salmon Steward magazine 7 C owichan Chinook are a key "indicator stock" for the Lower Georgia Strait, meaning their abundance influences decisions made on U.S. and Canadian catch limits through the Pacific Salmon Treaty. It also means that they have been studied since 1988 and a good baseline of data already exists. Both are reasons that they are a focus of the Pacific Salmon Foundation's Salish Sea Marine Survival Project. But research by project partner the British Columbia Conservation Foundation (BCCF) has revealed some puzzling results. In 2017, PSF funded a study using electronic tags to track Chinook in Cowichan Bay. BCCF discovered that between entering the river and about seven kilometres upstream, around 60 per cent of the tagged fish disappeared. "We know that all of the fish need to swim past log booms, which are popular haul-outs for seals," says Jamieson Atkinson, project lead for BCCF. "The issue is being exacerbated by low flows in the river from climate change – less water means more exposure to predators. However, there are also other factors such as stress, disease and poor water quality. So the big question is – are these losses being caused by seal predation or something else?" The study is the first to research the relationship between seals, log booms and salmon. Advances in tagging technolog y have helped make it possible. Old acoustic tags would simply triangulate location. But new acoustic tags can tell you how fast and how deep a fish was swimming when it died. If the fish was swimming fast and deep, it was probably trying to escape a hungry seal. The Pacific Salmon Foundation, Cowichan Tribes and Living Rivers Georgia Basin are a ll funders of the study. This year's study, which will run from August to November, is benefiting from some unique conditions on the river. Atkinson explains: "One of the forestry companies is on strike this year, so there aren't any log booms. In past years, we've seen up to 300 seals hauled out; this year, there have been less than 12. If there's a big difference in Chinook losses between 2019 and next year, we should have our answer." Working with industry and government on solutions will be part of ongoing efforts through the Salish Sea Marine Survival Project. LOG BOOMS, SEALS AND SALMON Cowichan Tribes member Wayne Paige, Jr. is working with BCCF to study tagged Chinook. JAMIESON ATKINSON, ISTOCK PSF is studying how log boom storage facilitates seal predation on salmon. The findings will inform recommendations for new estuary management practices with salmon as a priority.