Swinomish participate in study of 2021 heat on shellfish

To Julie Barber, a marine scientist for the Swinomish tribe, the scale of shellfish mortality on the beach was unprecedented. She had never seen anything like it in her 12 years of working for the tribe.

Barber emailed her colleagues throughout the state — scientists, co-managers, other tribes — and asked whether they were seeing the same things on their beaches.

In late June 2021, a heat dome spanning Oregon, Washington and British Columbia, pushed temperatures to well above 100 degrees. Afterward, reports of dead and dying shellfish on beaches up and down the Salish Sea and along the coast started coming in.

“I went out on the beach with my colleague … during the low tide, during the hottest day of the heat dome (and saw the devastation),” Barber said. “... I realized that I needed to be talking with my colleagues about this.”

The email chain Barber started expanded as federal agencies, nonprofits and researchers joined the conversation, with an urgency to document the unprecedented nature of the event in real time.

Wendel Raymond, a research scientist at the University of Washington’s Friday Harbor Laboratories, led the charge.

He was lead author of a research team set up to create the first comprehensive report of the impacts of the 2021 heat dome on shellfish. The report was released on June 21, 2022.

Overseeing the development of the study’s data-collection methodology, data analysis and writing of the manuscript, Raymond organized the contributions of his co-authors and those contributing survey data from Washington to British Columbia.

The study, funded by Washington Sea Grant, relied heavily on the local knowledge of tribes, state and federal agencies, academia and nonprofits, to conduct simple surveys ranking the conditions of various shellfish species following the heat dome from 108 locations.

Raymond said the participating tribes were essential to the study’s success as they represent a major manager and steward of shellfish resources, with important knowledge and understanding of regularly monitored tribal beaches.

“This project wouldn’t have been possible without this really diverse collaborative group of people that came together,” Raymond said.

Barber and other members of the Swinomish tribe’s fisheries department headed out to the beaches two weeks after the heat dome to conduct annual tribal shellfish surveys.

Unlike species such as butter clams that bury themselves deep into the cool sand, cockle populations sustained higher rates of mortality as they live on and near the surface of shorelines, Barber said. Standing on the beach, it was obvious the Swinomish researchers were going to see significant losses in the cockle population.

“When a clam or an oyster dies, there’s a very fresh clean shell. … They’re just kind of a clean, fresh clam like what you would have on your plate at the end of dinner at a restaurant,” Barber said. “And they were all over the beach. It was very obvious that there was a mass mortality event that just killed all those cockles.”

As the heat dome struck during the shellfish reproductive season, the event’s effects have the potential to ripple and affect shellfish populations for years.

Quintasket said the heat dome’s impact on the cockle population has resulted in the continuing closure of the tribe’s primary beaches for cockle harvest, and has affected the tribe’s traditional harvest diet and means of financial income.

Clams serve as a cultural keystone species to the tribe, providing activities including harvest, educational opportunities, and chances to pass down knowledge and spiritual practices to future generations.

“It’s harmful spiritually just seeing the devastation of the clams because our relationship with this place is a lot different than it is for non-tribal people,” Quintasket said. “We’ve always been caretakers, and the relationship is very much reciprocal with … our relatives of the land, the sky and the sea.”

For the Swinomish tribe, the study provides information to help it better prepare for the future, Quintasket said. The tribe has an action plan in progress regarding the stewardship of shellfish as it relates to climate change resilience and adaptation.

Raymond said in a world of worsening climate change, a heat dome event could occur once every five to 10 years, potentially resulting in compounding effects on shellfish populations, especially as reproductive seasons coincide with the summer months.

The UW study will act as a guiding compass for conducting further research on the thermal resilience of shellfish, Raymond said. Certain locations and species exhibiting potential resilience to heat events served as an exciting pattern in the study.

While Barber praised the unofficial formation of the group of scientists and co-managers that documented the effects of the 2021 heat dome on shellfish, she said having a more coordinated response for the next similar event would be of utmost importance.

“We (worked) together on all of this stuff, and with everyone that I (worked) with — the different tribes with the state, the great scientists — it was a real joy to be able to work with everyone on this paper,” Barber said. “We weren’t just going to let this go undocumented.”