"A study shows that watershed logging can be as bad for salmon numbers as increased predation in the ocean."
"A new study stands as a striking reminder that logging watersheds has an outsized impact on salmon and trout.
Led by Kyle Wilson at Simon Fraser University in British Columbia, the study looked at the successes and failures of five species of salmonids in the Keogh River (called Giyuxw by the local Kwakiutl First Nation) on northern Vancouver Island. For steelhead trout, the salmonid Wilson and his colleagues had the most data for, the problems the fish faced in the BC river hit the population just as hard as the challenges they faced out at sea. Wilson suspects the same holds true for other species with similar life cycles.
“Most people point to marine impacts as the biggest thing affecting salmon survival. This counters that,” Wilson says.
Chinook, coho, and steelhead populations in the Salish Sea have declined by up to 90 percent over the past 40 years. Canada declared several populations of steelhead endangered in 2020. Unpicking exactly how and why fish are crashing has proved hard. Whatever happens to the fish out at sea has been seen as something of a black box, so much recent research has focused on marine survival. Those efforts point to multiple culprits for declining salmon numbers, including climate change, overfishing, reductions in the salmons’ food, and rebounding populations of seals and Steller sea lions that gorge on the fish. Wilson’s research, however, highlights the need to keep our eyes on terra firma."