This year’s forecasts for coho coming back to the deep South Sound show the lasting impact of poor marine survival caused by the recent Pacific Blob, a large area of warm ocean water. For example, this coming year, only 1,800 coho that originated from the Squaxin Island Tribal net pens program are expected to return.
Usually over 25,000 Squaxin net pen coho return yearly from 1.8 million released. Historically, the net pen program’s survival has been as high as 3 percent in recent decades, but has dipped down to 1.1 percent the last few years. This year, the fish produced by the program will likely only have a 0.117 percent survival rate.
And, this is because of the lasting impacts of poor marine survival caused by the blob, even though it likely died this last fall.
Coho returning this year still spent enough time in the ocean that their survival was hurt by the blob’s warm water conditions.
“When young salmon come out to sea and the water is warm, they need more food to keep their metabolic rate up, yet there is less available food and they have to work harder,” said Elizabeth Daly, an Oregon State senior faculty research assistant with the Cooperative Institute for Marine Resources Studies, a joint program of OSU and NOAA.
“Our long-term data set contradicts the long-held assumption that salmon eat less during warm-water regimes,” Daly added. “They actually eat more. But they still don’t fare as well. When the water is warm, salmon are smaller and thinner.”
During the last two years, an unusually large, warm body of water has settled into the ocean off the Pacific Northwest that scientists have dubbed “The Blob,” which is forecast to be followed this winter by a fairly strong El Niño event. Though recent spring Chinook salmon runs have been strong due to cooler ocean conditions in 2012-13, the impact of this long stretch of warm water on juvenile fish may bode poorly for future runs.
“So far this year, we’ve seen a lot of juvenile salmon with empty stomachs,” Daly said. “The pressure to find food is going to be great. Of those fish that did have food in their stomachs, there was an unusual amount of juvenile rockfish and no signs of Pacific sand lance or krill.
“Not only does this warm water make it more difficult for the salmon to find food, it increases the risk of their own predation as they spend more time eating and less time avoiding predators,” she added.
The blob being replaced by a strong El Niño still means bad news for salmon survival.
El Niño is generally a warming of the Pacific Ocean that will likely last at least through this spring.
Last year’s returns of pink and coho salmon showed the devastating impacts bad marine survival can have on fisheries. Squaxin tribal fishers spent several frustrating weeks last fall landing fewer coho that were undersized as well.
Many of the fish we caught were about half the size of the fish we usually see. This was hard on our fishermen because for the same effort, their landings had much less value.
The Squaxin Tribe practices a protective fishing regime, focusing its efforts away from bays and harbors where wild coho congregate, fishing instead where plentiful hatchery-origin fish hang out.
Poor marine survival threatens the return of hatchery fish too, and will continue to hurt the tribe’s fishing-based economy and local sport fisheries. The Squaxin net pens program releases 1.8 million coho each year. When these fish returning as adults, they contribute to both sports fisheries through out Puget sound as well as tribal fisheries.
This decline in coho is devastating for both tribal and state-managed fisheries.