The Alaska Department of Fish and Game’s fish count shows nearly 155,000 sockeye salmon have passed the counter on the river from mid-May to Sunday, KTUU-TV reported .
More than 320,000 sockeye salmon swam up the river during the same period last year, according to the department.
Warmer ocean temperatures may be contributing to the decline, said Art Nelson, a department spokesperson for commercial fisheries.
“One of the theories is that there had been a number of years of unusually warm water in the North Pacific that was referred to as the blob, and that is one of the things that folks believe is leading to the poor productivity, poor feed for the salmon and then poor salmon productivity because of that,” Nelson said.
The changing temperatures could affect the salmon harvest in the Copper River, said Nick Bond, a research scientist at the University of Washington and a state climatologist. Bond coined the term “blob” to refer to a large mass of warmer than normal water in the Pacific Northwest that was first noted in 2013.
“The ecosystem is a complicated system with a lot of different interacting parts to it, but we’re seeing disruptions of various sorts in the marine food web,” Bond said. “Certainly, a working hypothesis is we’re seeing the working hangover of the blob.”
Salmon populations that are returning this year probably went out to sea during one of the first years of the blob, Bond said.
The surface ocean temperatures around Alaska are mostly moving closer to the average temperature, he said. The marine environment may return to a more normal condition, but other effects may become apparent later, he said.
The returns for most species are currently low, which may drive salmon prices higher across the state this summer, Nelson said.
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