The Alaska fishing season has only just begun, but early indications are the Cook Inlet king salmon collapse is developing just about as forecast by the Alaska Department of Fish and Game.
With the exception of the Anchor River near the southern tip of the Kenai Peninsula and hatchery-boosted Ship Creek in the heart of the state’s largest city, returns generally look grim.
The early-run of the big fish to the fabled Kenai River – the state’s most popular salmon stream – is so far lagging behind last year when the river failed to meet the spawning goal of 3,900 fish larger than 34 inches.
Only about 250 kings have been counted through the weir on the Deshka River, the most popular salmon stream in the Matanuska-Susitna Borough north of Anchorage. That’s better than last year when the return reached only about 65 percent of the minimum spawning goal of 13,000 kings, but not by much.
Expecting this, the state in January announced the closure of Mat-Su king salmon seasons for summer. The move hit Mat-Su tourism businesses hard.
By the start of June in the boom years of the 2000s, anglers would sometimes see thousands of kings through a weir upstream from a Deshka-Susitna rivers confluence so packed with boats and anglers it was sometimes hard to imagine a fish could get through all the hooks.
It was the good old days.
The big mystery
What has happened since no one knows although Pacific coast-wide problems with kings, or Chinooks as they are known in many other places, point to low ocean survival.
When runs started faltering in 2007, the state put considerable effort into trying to figure out why and was only able to conclude that “that most of the Chinook salmon mortality is occurring in the first few months of life at sea.”
It’s complicated, a 2016 state summary of the research concluded: “Numerous physical and biological factors can influence production and survival of Chinook salmon in the freshwater and marine phases of their lifecycle.”
There are no commercial, sport or other fisheries removing kings bound for the Inlet, and the spawning habitat for the fish – especially that for the early-run Kenai kings – is largely untouched by the hands of man.
Some lower-48 biologists have suggested the big kings are losing out to smaller, far more numerous pink salmon in the competition for food at sea. But state fisheries biologists say the marine food web in the Pacific is so complicated no one can be certain of this cause.
Ironically, the king fisheries doing best in Cook Inlet at this time are hatchery-supported fisheries at Ship Creek, the Eklutna Tailrace just north of the city, and the Nick Dudiak Fishing Lagoon in Homer.
Even there, however, the kings are few comparison to pinks, many of them hatchery fish. Pinks are a mainstay of the Alaska commercial fishing industry. The state banned net-pen farming of salmon about 30 years ago, but it is a global leader – second only to Japan – in the open-ocean farming of salmon.
A peer-reviewed study published in Nature Ecology and Evolution in May reported that is in part thanks to a warming ocean that allowed “the biomass of salmon (to double) between 1960 and 2010.
“This increase is due in part to greater wild salmon abundance, but has been largely driven by hatchery releases of Pacific salmon by the surrounding nations. Recent estimates attribute 40 percent of Pacific salmon abundance to hatchery-produced fish, although this estimate is conservative as hatchery fish that spawn naturally are not counted.”
The study was aimed at Bristol Bay sockeye salmon. Those fish support the state’s most valuable salmon fishery. The study concluded warming waters in Bay lakes are making salmon grow faster and go to sea sooner, which should theoretically boost salmon numbers, but competition for food at sea limits how much the sockeye can find to eat and they are thus forced to spend an extra year in the ocean before maturing and returning to spawn.
“The positive effects of climate change for earlier migration to the ocean, which may increase population productivity, are largely dampened by longer ocean residence,” the scientists concluded. “The evidence for overcrowding of salmon in the ocean and increased competition for resources has been gaining strength. Hatchery production has increased substantially since 1970, and there is high spatial and trophic overlap between sockeye, pink and chum salmon in the North Pacific.”
Chinook also appear to be in that mix. Seattle research biologist Greg Ruggerone and Alaska state fisheries biologist Beverly Agler in 2010 reported finding changes in the growth patterns of Chinook in the Bering Sea that appear linked to abundant pinks.
In a report prepared for the Arctic Yukon Kuskokwim Sustainable Salmon Initiative Project Product, they wrote that “alternating-year patterns in Chinook salmon growth at sea were detected and may reflect direct and/or indirect interactions with pink salmon, which are exceptionally abundant in the Bering Sea during odd-numbered years.”
Russia is this year forecasting a catch of about 300,000 metric tonnes of pink salmon or somewhere in the neighborhood of 190 million of the fish. The 2015 Alaska pink salmon catch of 190.5 million, the second largest in state history, weighed 295,420 tonnes.