July 13, 2023 — Rates of Chinook salmon bycatch in the Pacific hake fishery rise during years when ocean temperatures are warmer, a signal that climate change and increased frequency of marine heatwaves could lead to higher bycatch rates, new research indicates.

During years when sea surface temperatures were higher, including during a marine heatwave, Chinook salmon were more likely to overlap with the Pacific hake and raise the risk of bycatch as they sought refuge from higher temperatures.

The findings, based on 20 years of bycatch data and ocean temperature records, provide new insight into the ecological mechanisms that underlie bycatch, which is the incidental capture of a non-targeted species, said the study’s lead author, Megan Sabal.

“The impact of ocean warming on bycatch has potential cultural, economic and ecological consequences, as the hake and salmon fisheries are each worth millions of dollars and salmon are critical to both Indigenous tribes’ cultural heritage and healthy ecosystems,” said Sabal, who worked on the project as a postdoctoral scholar at Oregon State University.

Pacific hake, also known as Pacific whiting, is the largest commercial fishery by tonnage on the U.S. West Coast. The rate is low but bycatch remains a concern for the Chinook salmon population, said Michael Banks, a marine fisheries genomics, conservation and behavior professor at Oregon State University and a co-author of the study.

“The hake fishing industry is very sensitive to the impacts of bycatch on salmon and has been diligent in reducing it, but changing climate conditions might become an increasing issue,” he said.

The research was just published in the journal Fish and Fisheries.

Pacific hake school in midwater depths off the West Coast from southern Baja California to the Gulf of Alaska. Hake is commonly used in surimi, a type of minced fish used to make imitation crab.

Read the full article at PHYS.org