The 2020 decline in North Pacific salmon numbers appears to have been the greatest in recorded history, according to a trio of scientists who’ve spent much of their careers studying the secret lives of salmon in the ocean.
They suggested to the North Pacific Anadromous Fish Commission (NPAFC), an international monitoring group, that the crash was likely driven by warmer ocean waters and an explosion of pink salmon in 2018 and 2019.
“We hypothesize that a tipping point was reached in the North Pacific Ocean, leading to the substantial decline of all five species of Pacific salmon in 2020. We infer that the tipping point was caused by the combined effects of unusually frequent marine heatwaves since 2014 and exceptional back-to-back year abundances of pink salmon in 2018/2019,” Seattle-based fisheries consultant Greg Ruggerone and colleagues James Irvine and Brendan Connors with Fisheries and Oceans Canada told the NPAFC during a virtual meeting.
As with the 2018/2019 peak in salmon abundance – driven largely by pinks – the 2020 collapse was unprecedented, they noted:
“Unexpectedly, the high abundance of Pacific salmon came to an abrupt end in 2020. Preliminary commercial catch statistics for all salmon species indicate Pacific salmon harvests, which provide an index of abundance, declined more in 2020 than in any other period on record since 1930.
“Commercial salmon harvests declined by approximately 187 million fish compared with average harvest during the previous 10 years. Although the Covid-19 pandemic may have reduced commercial harvests to some extent in some regions, most fishery reports and preliminary escapement estimates indicate low abundance rather than harvest impacts from the Covid-19 pandemic led to unusually low harvests of Pacific salmon in 2020.”
Chinook – the longest-lived and biggest of the fish, the salmon Alaskans simply call “kings” – took the biggest hit.
“Harvests of Chinook salmon in 2020 were the lowest on record since 1925, declining 54 percent compared with the previous 10 years,” they wrote.
North Pacific kings have been in a steady downward trend for years. In a peer-reviewed study published in Fish and Fisheries last fall, scientists from Kintama Research Services in Nanaimo, British Columbia, Canada, have documented a 65 percent decline in survival for Chinook spawned in the streams from the northern end of the Alaska Panhandle south along the Alaska and Canadian coasts all the way to Oregon.
Though the study did not include Chinook spawning systems north of the Panhandle because of a lack of data, the kings of the Copper River, Cook Inlet and Kodiak Island appear to have declined in number along with all the other Chinook stocks that spend their lives in the Gulf of Alaska.
“The abundance of salmon in the North Pacific has reached record levels,” the Kintama researchers wrote. “However, most of the increase is in the two lowest valued species (pinks and chums) in far northern regions, at least in part due to ocean ranching.
“In contrast, essentially all west coast North American Chinook populations including Alaska are now performing poorly with dramatically reduced productivity.”
That trend only grew worse in 2020 as the overall boom in abundance turned into a big bust with pinks, the big driver of record catches, down 40 percent and chums down 42 percent, according to Ruggerone and colleagues.
Chums and pinks are the two species most extensively free-range farmed in the North Pacific. The U.S. is now the world leader in this sort of salmon farming with Alaska producing about 90 percent of the hatchery fish.
“Most pink salmon are of natural origin,” Ruggerone, Irvine and Connors observed, “but abundance of hatchery pink salmon during 2005 to 2015 was greater than abundance of wild chum salmon and approximately equal to abundance of wild sockeye salmon.”
The 2020 commercial harvest in Cook Inlet of “approximately 1.2 million salmon was 65 percent less than the recent 10-year average harvest of 3.2 million fish,” according to the Alaska Department of Fish and Game.
The fishing was even worse off the mouth of the Copper River.
“The Copper River had one of the weakest sockeye salmon runs on record with minimal fishing opportunity and the third smallest commercial harvest in the past 50 years,” the state agency reported. “The sockeye salmon commercial harvest of 102,269 fish was 92 percent less than the 10-year harvest average of 1.3 million fish.”
Historically, Cook Inlet and the Copper River support two of the state’s largest fisheries for Gulf of Alaska sockeye. The Inlet fishery just south of Alaska’s largest city is only just beginning, but another weak return is forecast.
A weak return was also forecast for the Copper, and it has turned out to be worse than expected. With the run there past its peak, the catch is reported at under 195,000 sockeye – better than last year but less than percent of the forecast harvest of 652,000.
When the sockeye return to the Copper started off weak, the state closed many of the regularly scheduled fishing periods in late May and early June, and though the fishery is now open, many fishermen have deserted it in hopes of finding better fishing elsewhere.
Only 82 boats reporting landing fish on Thursday, according to Fish and Game. That’s down from a peak of 451 on May 24. Average landings of more than 150 per boat were the best of the season, but the overall catch was less than 12,500 fish.
Unfortunately for them, an estimated 70 percent of the return is usually in river by now.
The good news is that sockeye and Chinook runs are almost everywhere looking better than in 2020, and the state is predicting an overall harvest of more than 190 million salmon, almost twice the 100 million that used to be considered a good season in the 49th state.
The catch, however, is forecast to be driven by those booming Bristol Bay returns and pinks, or what Alaskans often call “humpies.” About a quarter of the fish are expected to be Bay sockeye with another 65 percent pinks.
“If realized, the 2021 forecasted commercial harvest of 190.1 million salmon will be substantially larger than the harvest of 2020, mostly due to the projected harvest of pink salmon,” Fish and Game conceded.
Pinks are the smallest and least valuable of the state’s salmon. Last year, the state reports, they averaged less than three and half pounds and were worth 30 cents per pound to commercial fishermen.
Sockeye averaged over 5 pounds on average and brought 76 cents per pound on average. The catch of 46 million ended up worth nearly $180 million to commercial fishermen, about three times the value of the larger, 59.5-million catch of pinks.
CORRECTION: This is a revised version of an earlier story. It was edited to clarify that the Kintama study found a 65 percent decline in survival of Chinook.