Submitted by Kwiaht
Tiny crustaceans smaller than a rice grain may hold the key to understanding why Chinook salmon and seabird numbers in the San Juan Islands fell sharply in 2016-2017, and why that drop coincided with unusually warm summers.
“Copepods are voracious grazers that reproduce frequently,” explained Russel Barsh of the Lopez ecology laboratory Kwiaht. “They feast on diatoms, which are armored algae that convert sunlight into sugars. Copepods convert diatoms’ carbohydrates into a calorie-rich sweet orange oil that make copepods the favorite prey of fishes such as herring and sand lance, which in turn are the principal prey of Chinook salmon and many seabirds.”
Copepods are small and fast swimmers, however. Catching and eating a bellyful of them can be a lot of work. “It can take 500 to 1,000 copepods to make a day’s meal for a small fish,” Barsh said. “Unless they are one of the larger copepod species, which can be 10 to 20 times larger. The rub is that large copepod species are associated with colder waters than we have been seeing lately around the islands.”
Warmer seas produce smaller copepods, forcing forage fish to work harder for each meal. This may result in slower growth and less viable eggs.
This is just one of many new insights that will be shared at this year’s SalmonAtion event at Lopez Center, on Saturday, Jan. 26, from 5:30 p.m. to 7:30 p.m. As always there will be a light buffet with a choice of Lopez Island Vineyards wines, and a musical offering (this year by Stanley Greenthal), as well as a slideshow reviewing highlights of this past year’s research. Gyotaku print makers Jill Marks and Ruth van Doren are this year’s featured artists, and their work will be on display. Admission is free.
SalmonAtion 2019 will also re-examine what islanders can do to help mitigate the impacts of climate change on salmon, marine mammals and birds, such as landscaping and planting along shorelines to protect water quality and critical habitat; minimizing use of outdoor products that contain persistent toxics; and rebuilding the islands’ lost oyster reefs and salt marshes. Kwiaht’s bio-engineering program offers free technical assistance to homeowner, and you can learn more by speaking with Kwiaht science staff at SalmonAtion and making an appointment for a site visit.
Kwiaht volunteers fish Watmough Bight from May to September and welcome visitors to help pull nets and sort fish. Schedules will be available at the Jan. 26 Lopez Center event, or you can write to firstname.lastname@example.org for more details. Volunteers are also needed for seabird and shorebird counts that help Kwiaht researchers monitor changing coastal habitats around Lopez, and better understand how seabirds and salmon compete for fishy prey.