The Journal –
For a third year, salmon researchers from the Lopez Island-based nonprofit Kwiaht will be staffing winter Blackmouth fishing derbies to help clean fish, collect gut contents, and learn more about the diet and health of these iconic resident Chinook salmon.
“Smaller and fewer Blackmouth salmon is a concern for Southern Resident Killer Whales as well as our fishing community,” says Kwiaht director Russel Barsh, who has been studying the changing diet of Chinook salmon for over a decade. “We want to find the bottleneck in the food web so that it can be addressed while there is still a good chance for Blackmouth recovery.”
Blackmouth sampled at derbies in 2018 and 2019 had mainly eaten Pacific herring, Barsh says; “nearly four-fifths by dry weight of what we found in 324 Blackmouth.” All other fish made up barely three percent of the diet. When they did not find herring, Blackmouth sampled in 2018-2019 mainly ate shrimp. Few squid were found in gut contents, although Blackmouth were hitting lures that mimic squid. “We were surprised to see hardly any Pacific Sand Lance in these salmon,” Barsh adds. “Sand Lance can be almost half the diet of juvenile Chinook in the islands, but it looks like they eat proportionately more herring as they grow larger.”