‘More hungry mouths’: Bristol Bay sockeye are abundant but shrinking

Tiny fish swimming in green-colored water.
Salmon fry swimming through rocks. (Brian Venua / KDLG)

Bristol Bay is home to the largest sockeye run on the planet. But while the size of this year’s run broke records, the fish are getting smaller.

Last year’s average weight for sockeye was 5.1 pounds. The 2021 average was just 4.5 pounds, according to the McKinley Research Group.

The smaller fish play a role in how much time processors spend on the job, said Jon Hickman, the executive vice president of operations for Peter Pan Seafoods.

“Smaller fish are going to take longer to process,” he said. “So you’re handling a 4-pound fish or a 3-pound fish, as opposed to a 5-pound fish, so every time you handle one there’s a 2-pound difference. There’s more labor going into those smaller fish. You get more labor into them, there’s more costs associated with those smaller fish.”

RELATED: Meet one of Bristol Bay’s salmon counters who tallied sockeye during the biggest run on record

Hickman said he isn’t worried about how the smaller fish will play in Peter Pan’s markets. Demand is good, and he’s comfortable with the market for fish big and small.

But why are Bristol Bay’s salmon shrinking? 

First, the returning fish are younger than normal.

A salmon’s age is measured by how many years it spends in the ocean. A 2-ocean fish, for example, has spent two years in the ocean before returning to its spawning grounds.

Greg Buck, a biologist for the Alaska Department of Fish and Game, said most fish that returned this year only spent one or two years in the ocean instead of three.

“I’m gonna be gambling like it’s somebody else’s money when it comes to the age of 1-2s in the next year’s forecast,” he said. “I’ve been burned a couple of times. I’m normally kind of conservative when I forecast, but this year I might not be.”

RELATED: Bristol Bay records its largest sockeye run on record

But Dan Schindler, a researcher with the University of Washington’s Alaska salmon program, said fish are also smaller for their age.

“The size of fish has declined for their age,” he said. “So the size of 2-ocean fish has been declining slowly over time, and the size of 3-ocean fish has been slowly declining over time.”

The sheer number of fish can lead to more competition for food in the ocean. Large runs — like this year’s record — tend to have smaller fish. There are also more salmon in the North Pacific ocean now than there have been in over a century due to an increase in hatchery pink and chum salmon.

“This declining size at a given age is really a function of more hungry mouths from lots of Bristol Bay fish, but also more hungry mouths that we’re dumping out into the ocean,” Schindler said.

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Until recently, scientists and the fishing community didn’t pay much attention to the shrinking salmon trend. That’s because in the 1970s, more salmon started to spend an extra year in the ocean. And older fish usually come in bigger than their younger counterparts. But, Schindler said, in the last 10 years, more fish have returned after two years.

“So right now, we’re sort of seeing the effect of a double-whammy on fish size,” said Schindler. “And the last four or five years — we’ve seen a lot of really small fish in the catches and the escapements. That’s because there’s a lot of 2-ocean fish, and those 2-ocean fish are relatively small given the history of Bristol Bay.”

Warming oceans also may play a role. But Schindler said the connection is less direct. Warmer oceans have been correlated with increased survival for Bristol Bay salmon, which means more competition for food.

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