A controversial study pointing to the ocean – and not dams or other freshwater issues – as responsible for a 65 percent decline in the productivity of Chinook salmon along the North American coast has also stumbled on evidence that Columbia River Chinook salmon are being badly overfished.
After being stuck in peer review for over a year and a half, the document has now been published by Fish and Fisheries, and it could have serious implications for the commercial troll fishery off the coast of Southeast Alaska.
That fishery depends heavily on the interception of Chinooks bound for Canada and the Pacific Northwest. Given its long, historic nature, trollers contend they are entitled to a share of the fish that pass through and graze upon Alaska pastures, but their harvests have come under increasing fire as Chinook stocks falter in the Columbia drainage.
Slumping Chinook survival was once thought to be a problem unique to the heavily developed Lower 48, but it has crept noticeably north in the past decade as well.
And the new study led Canadian David Welch and his associates at Kintama Research Services in British Columbia concludes the king salmon rivers of the state’s wild, untrammeled, little populated Panhandle region are now producing worse than those of southern regions dominated by agriculture, industry, freeways and big cities.
But the decline in productivity doesn’t appear to have anything to do with the terrestrial landscape. Instead, the problem appears to be that Chinook runs are limited at this time by unknown conditions in the ocean.
Commonly called king salmon in Alaska and prized as the largest of the salmon species, Chinooks in the Lower 48 have been the subject of much discussion for decades because of the belief their numbers have been decimated by hydroelectric dams on the Columbia and its tributaries.
The new study first completed by Canadian biologists in Nanaimo in 2018 challenged that widely held belief when it reported data indicating the decline of the big fish really appeared linked to poor ocean survival.
After months stuck in peer-review, the much-challenged study was eventually posted on bioRxiv, a non-peer-reviewed website for scientific studies. When craigmedred.news reported on the study in September of last year, it had already been seven months under study by reviewers with the authors’ challenge to conventional wisdom facing a sustained, professional attack.
Criticisms of the draft led Welch and his colleagues to search for more data to support their conclusions, and it was then they discovered that biologists studying Columbia salmon survival using passive integrated transponders – so-called “PIT tags” – were not accounting for the tags in fish that fell victim to commercial and sport fisheries on their way back to the river.
As a result, adult salmon disappeared into those fisheries leading to a serious undercount in the actual size of the adult return.
“The Kitama team showed that the harvest of different Chinook populations returning to the Columbia River was large and increasing over time. As a result, the PIT-tag system in the Columbia River was measuring what escaped from the fishery and was not just measuring the survival influenced by the dams as originally thought.”
Welch emailed that he and his colleagues are not arguing the dams have no effect on Columbia salmon numbers, but their data would indicate the damage might be far less than long believed.
“The team’s results suggest that the dams’ influence could be minor, and they aren’t a major factor affecting salmon productivity,” concluded Scientia Global, a research publication for scientists and policymakers summed the study.
Though now published in the peer-reviewed Fish and Fisheries, the study is likely to remain controversial in that it was funded in part by the Bonneville Power Administration, the federal agency that Congress designated to market power from the Bonneville Dam on the Columbia and 30 other federal-owned hydroelectric facilities in the Pacific Northwest.
Environmentalists, fishermen and Indian tribes have long been advocating for the removal of the dams because of the salmon management problems they create.
Fish versus power
All those groups reacted angrily earlier this year when a federal study rejected removing four dams on the Snake River, a major Columbia tributary, in what the Associated Press described as “a last-ditch effort to save more than a dozen species of threatened or endangered salmon.”
The report concluded removal of the dams would destabilize the regional power grid, force an increase in greenhouse gas emissions and more than double the risk of regional power outages in five million homes scattered across more than a half-dozen Western U.S. states.
While a high-profile debate about the dams’ effect on salmon has raged for years, the widespread decline of Chinook salmon stocks from Alaska south to California has attracted much less attention.
Poor “ocean survival” has often been cited in years when kings returned in low numbers to the Kenai, Susitna, Copper and other well-known watersheds in the 49th state, but prior to the Kintama study, no one had gone looking to find a pattern that might define the decline.
There are, in fact, now more salmon in the North Pacific than at any time in recorded history, researchers report; the problem is not many of them are kings.
“The abundance of salmon in the North Pacific has reached record levels,” the Kintama researchers concede. “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.”
The study did not look at all Alaska king stocks because of a lack of data, but in total it examined 123 Chinook runs from the northern end of the Alaska Panhandle south to northern California. All those runs had data available from PIT or old-fashioned, coded-wire tags that allowed the group to calculate smolt-to-adult return (SAR) rates for the fish.
What the researchers discovered surprised them and made their study stir debate.
As they write, “the historical pattern of declines in salmon abundance (steeper in the south, less so in the north) were originally assumed to reflect a freshwater (human-driven) cause because of the greater degree of freshwater habitat modification in the more populous southern regions.”
But that is not what they found. Instead, the data pointed to a steady decline in SAR for Chinook everywhere along the coast since a regime change in the late 1970s shifted the waters of the North Pacific from a generally cooler to a generally warmer state.
Losers and winners
That same regime change has been credited with Alaska’s salmon bounty. State salmon harvest hit rock bottom in the 1970s when the ocean was full of cold water.
The 1973 and 1974 commercial harvests of 22 million salmon were but 12 percent of the decadal average annual harvest for the 2010s. Alaska’s ocean-ranching hatcheries based in Southeast, Prince William Sound and on Kodiak Island now sometimes produce nearly 10 times as many salmon as the entirety of the state’s wild rivers produced in ’73 and ’74.
But the indications are that this change has not been good for the big salmon officially designated the state fish. Whether this is due purely to the warm waters, competition for food with faster growing and far more plentiful pink salmon, predation from seabirds and marine mammals whose populations were boosted by the new, overall abundance of salmon or other factors is an unknown.
“Given the widely recognized poor survival of Snake River Chinook salmon, resulting in their listing under the US Endangered Species Act, many of our analyses compare regional survival to that of the Snake River region,” the Kintama researchers wrote. “We show that, overall, Chinook salmon survival has decreased by roughly the same amount everywhere along the west coast of North America and has now reached similar or lower survival levels than Snake River stocks.”
Among the stocks showing lower survival levels than the Snake are the five in Southeast Alaska included in the study. The Kenai River – the most famous king salmon river in the state and home to the 97-pound, 4-ounce world record catch on rod and reel – was not included in the study, but the king struggles there are well known.
The river failed to meet its minimum spawning goal in 2019 and again this year despite strict limitations imposed on sport and commercial fishermen to minimize harvests.
The Susitna River, a huge watershed draining the south slope of the Alaska Range, just north of the state’s largest city, and the Copper River, a massive waterway draining the many glaciers of eastern Alaska, have also seen kings struggle in recent years.
The results of the Kintama study do not appear to bode well for these and other Alaska king salmon fisheries.
“At the broadest level, the major implication of our results is
that most of the salmon conservation problem is determined in the
ocean by common processes,” the authors wrote. “Attempts to improve SARs by addressing region-specific issues such as freshwater habitat degradation or salmon aquaculture in coastal zones are therefore unlikely to be successful.”
They called for a “joint systematic review by major funding agencies” to attempt to determine what is going on with Chinook survival in the ocean.
It hasn’t been easy, he said, and sponsors are not exactly lining up to fund future research. The state of Alaska, once a leader in salmon research, has shied away from ocean studies.