The season for the most popular Alaska salmon in the state’s most populous region had only begun before it largely ended yesterday in another display of the sagging fortunes of Chinook salmon in the Pacific Ocean.
While populations of pink salmon, the smallest of the species, continue to boom – commercial fishermen caught 161 million of those fish in Alaska last year and streams in many areas are plugged with them on an annual basis – populations of the biggest salmon – those Alaskans like to call “king” – continue to fade.
The count of Chinook at the weir on the Deshka River, the most popular king salmon stream in the Susitna River valley, stood at 2,780 yesterday, the lowest on record since 2013 when the run arrived very late apparently due to unusually high water in the early season.
The Southcentral region of the state set a record for snowfall in the winter of 2012-2013 which produced high spring runoff. There is no expectation of a replay of the 2013 scenario this year.
Instead, a river that posted weir counts of 30,000 to more than 50,000 kings per year at the start of the new millennium, is unlikely to reach the 9,000 to 19,000 returns of recent years.
Gulf of Alaska wide, the Alaska Department of Fish and Game has documented a steady downward trend that began 15 years ago. Fisheries scientists have been trying to figure out why for more than a decade, but have largely gotten nowhere.
“Research…suggests that most of the Chinook salmon mortality is occurring in the first few months of life at sea and freshwater survival has been average or even above average,” the state agency says. “Additional research is needed to gain a better understanding of the primary factors that are affecting Chinook productivity and abundance, especially in the marine environment.”
There is general agreement among all the scientists that the survival problem is happening somehow and somewhere at sea, with state biologists noting that “the long-term marine survival for four Southeast stocks (had historically) been about four percent, meaning for every 100 smolt that emigrate to sea, four fish will return as adults over the next one to five years.
“(But) research has shown that during the recent period of poor production, marine survival has dipped below one percent. This decrease in marine survival, even in the face of some very good freshwater production in several systems, has been driving the downturn in overall adult production. The exact mechanisms behind the increased mortality rates are unknown.”
Fisheries researcher David Welch and associates at Kintama Research Services in Nanaimo, British Columbia, Canada, in the late 2010s uncovered evidence that this problem with ocean survival applies coastwide.
When they finally got a study reporting a 65 percent, coastwide decline in productivity from the northern end of the Alaska Panhandle to southern Oregon peer-reviewed and published in Fish and Fisheries in 2020, it mainly served to kick off a major brouhaha over dams on rivers in the Pacific Northwest.
Lost in the weeds
Because the study was funded by the Bonneville Power Administration (BPA), which runs the dams on the Columbia and Snake rivers, it was attacked as merely another attempt by those interested in hydropower to keep the dams up and running.
Mitch Cutter of the Idaho Conservation League declared the study had been “debunked” by federal scientists invested in the theory that all of the problems of the Columbia and its tributaries are tied to freshwater survival.
“The Bonneville Power Administration (BPA) funded Welch’s research, one of several papers that have deflected blame for fish declines away from the federal hydropower system, which BPA operates. BPA support of this type of research stands in stark contrast to peer-reviewed, scientifically rigorous studies that most fish biologists endorse,” Cutter charged. “Reputable studies have concluded that the biggest factor in the continued decline of Snake River salmon and steelhead is the hydroelectric system of dams.”
But he was getting his information from federal scientists married to the longstanding dogma that wild salmon production is all about in-stream survival. A growing body of evidence has, however, shown that view is simply outdated.
As Alaska – home to more undisturbed, freshwater salmon habitat than the rest of the nation combined – has been witnessing, what happens in the ocean matters.
The Kintama study wasn’t an attempt to distract attention from the dams, but an acceptance of reality. That dams are a detriment to the natural reproduction of salmon is a given.
They alter both the upstream migrations of adults and the downstream migrations of juveniles, and create reservoirs in which predators that feast on young salmon, such as northern pike and the northern pikeminnow, can thrive.
The latter, ironically, has created an economic opportunity for fishermen in parts of Washington state given the bounties now paid for killing northern pike minnows. From 2011 to 2020, the Washington Department of Fish and Wildlife reports, “the top 20 anglers caught an average of 3,353 fish per angler and averaged reward payments of $27,836 each for the five-month season. The highest-paid angler in 2020 caught 5,579 fish and earned $48,501, while the all-time record harvest is 14,109 northern pikeminnow worth $119,341!”
Not all of the freshwater survival problems humans have caused salmon can be solved by humans, but researchers have found ways to minimize them by cleaning up logging operations, filtering road drainage into rivers and streams, funding predator control, trucking salmon around dams and more.
Ocean survival presents a more complicated problem.
At this time, the ocean remains a vast unknown for teaming with hundreds of species of fish that all eat each other at different times and in different life stages. Bill Templin, the director of research for commercial fisheries with Alaska’s Fish and Game, four years ago dismissed ocean survival issues as simply too complicated to study.
But aging Canadian researcher Dick Beamish and a small band of supporters from Canada and the Pacific Northwest managed to kick start a major ocean research project in 2019 that has now been joined by the U.S. National Oceanic and Atmospheric Association and some scientists from Alaska Fish and Game.
Some of what they have found is obvious. Marine habitat, though it might all look the same on the surface, is much like terrestrial habitat beneath the surface in that it is a patchwork of productive and unproductive habitats.
In short, there are good pastures for growing salmon, bad pastures for growing salmon, and a lot of in-between pastures.
The biggest difference between the pastures here and on land are indications that the good pastures in the ocean can move around a lot depending on the shifting tides of nutrients in the water, sunlight and water temperatures.
The food web might be more complicated at sea than on land – what with all sorts of fish feeding on each other at times – but it is basically the same: Where plants (phytoplankton) thrive, the ocean supports more tiny animals (zooplankton), and together they form the base of a trophic pyramid that supports ever smaller numbers of ever-larger species of life, including marine mammals and humans at the very top.
The big issue at sea is how the blocks that build the pyramid interact, and there has come an increasing focus on the one occupied by those oh-so abundant pink salmon thanks, in part, to the free-range farming of the sea by commercial fishermen controlled hatcheries in Alaska, in part by the state’s management of pink slamon for maximum abundance across their range, and in part because of the warming of the ocean, which appears to benefit Gulf of Alaska pinks more than bigger sockeyes (reds), cohos (silvers) and those much-loved Chinooks (kings).
Four years ago, a team of scientists from Alaska, British Columbia and the Pacific Northwest hypothesized that a historic high abundance of pink and chum salmon in the Gulf, and sockeye in Bristol Bay where global warming has sparking a sockeye boom, could force a major ecological shift away from the production of Chinook and coho.
“High abundance of these species, especially pink salmon, cause a trophic cascade that reduces prey availability for higher trophic species such as Chinook and coho salmon in offshore areas,” they wrote.
A team of international scientists studying shearwaters, a seabird that migrates between Australia and the Bering Seas, have likewise pointed to pink salmon as a player in the crash of shearwater populations.
As they reported in the peer-reviewed Proceedings of the National Academy of Sciences of the United States of America in 2018, major shearawter die-offs happened from 2007 to 2013 as pink salmon populations were ever growing and were “another example in a growing list of ecosystem disservices of an abundant species of North Pacific salmon and the need to include ecosystem processes at such geographic scales in conservation and management considerations for this northern open ocean.
“Pink salmon in the North Pacific Ocean have flourished since the 1970s with growth in wild populations augmented by rising hatchery production,” they wrote. “As their abundance has grown, so too has evidence that they are having important effects on other species and on ocean ecosystems.”
This theory, however, remains far from scientifically proven, though there is increasingly interesting data being gathered including that which would appear to indicate that pink salmon have now become so abundant in even-numbered years that they supress the production of pinks in odd-numbered years.
Exactly how this yo-yoing abundance might affect other species of salmon is largely unclear, but various studies have now linked the big boom in pink numbers to the shrinking body size of longer-lived species of salmon and to a decline in sockeye salmon numbers in Gulf of Alaska watersheds.
There is enough evidence of disruption that scientists working with the North Pacific Anadaromous Fish Commission, a joint U.S.-Canada-Russia monitor of Pacific salmon populations, this winter posed this question:
They answered it with an observation of the declines in longer-lived species of salmon as pinks, the shortest-lived of the species, boomed, observed that “overall, pink salmon represented approximately 74 percent of total salmon abundance in 2018/2019. Most pink salmon are of natural origin, 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.
“Total chum and sockeye salmon represented only 14 percent and 12 percent, respectively, of total salmon abundance in 2018/2019. These values exclude Chinook and coho salmon, whose combined reported commercial catch was 1.5 percent of total salmon catch from the North Pacific during 2018/2019 and approximately 5 percent of total salmon catch, on average, during 1925 to 2020.”
In short, Chinook production appears more than a third less now than what it was historically. The number is interestingly close to that 65 percent reduction in West Coast production of kings reported by the Kintama scientists.