Anchors aweigh on international salmon voyage
Four vessels are heading into the Gulf of Alaska this winter to study the impacts of climate change on Pacific salmon.
The expedition is not the first international effort of its kind. But it will likely be the largest, uniting several countries in pursuit of clues about what changing ocean conditions do to salmon while they're out at sea.
Ed Farley studies salmon habitat and manages the Ecosystem Monitoring and Assessment Program with NOAA Fisheries in Juneau. He's joining the effort from the Bell M. Shimada, a NOAA research vessel leaving Port Angeles, Wash. tomorrow.
"These surveys really give us a glimpse of what the future might hold," he said. "That's why I’m out there.”
The expedition comes on the heels of years of heatwaves in the Gulf of Alaska. At the same time, salmon stocks are struggling throughout the region, from declining runs in Cook Inlet to devastating crashes in Western Alaska.
Scientists know winter is an important time for the species. It’s when stocks from around the sea mingle and compete for food in the Gulf of Alaska.
But there is still a lot to learn about what happens to salmon while they're there and how ocean conditions impact the survivability of the species.
“We’ve had summer surveys and coastal surveys where we can see impacts on the food web," Farley said. "But we have really not been out on the central gulf – especially in winter – when this next critical period is occurring, to see what's happening to salmon in this environment.”
Farley wants to know how warmer ocean temperatures will impact salmon. Ocean warming is only expected to get worse with time. Now-anomalous heatwaves could be previews of what’s to come.
He said there’s certain information scientists can only catch if they're out at sea. The Shimada will use a rope trawl to capture salmon and take samples, to see what they’re eating.
“And from there, you can tell whether or not these fish are stressed," he said.
They’re also going to analyze environmental DNA, or eDNA, to see what species are swimming in the salmon’s habitat.
eDNA is genetic material that animals shed into their environments. University of British Columbia biologist Christoph Deeg said at a recent presentation that some salmon predators are too smart or fast to get caught otherwise.
“These are species that are really difficult to get a handle on when you are using conventional methods like capturing them in a net," he said.
But they do leave traces of genetic material that vary depending on their species. One salmon predator, the salmon shark, has only ever been detected in the gulf with eDNA, Deeg said.
He said scientists will capture nearly eDNA samples from nearly 200 stations at multiple depths during the expedition.
Farley is hopping on the Shimada in Ketchikan for its first leg. He’ll be on the boat for 11 days, disembarking in Kodiak.
His crew will be joined at sea by vessels and scientists from Russia, Japan, the Republic of Korea and Canada. Altogether, they’ll cover an area spanning west of Adak down to the eastern part of the gulf.
Farley said the international cooperation is crucial. Fish don’t recognize borders.
"Stocks from all over the Pacific Rim are intermingling with each other," he said. "So it’s important to have an international effort to understand the impact of climate variability and change on our ecosystems and what’s going on during winter.”
Together, they can cover more ground – or sea – than they have ever have before.
To track the Shimada’s journey, visit yearofthesalmon.org/2022expedition.