The disrupters?

Pink salmon accused of pushing the Pacific ecosystem to a ‘tipping point’ /John R. McKillan, NOAA

A trio of North America’s top salmon scientists has underlined their belief a 2020 fishery collapse in the Pacific Ocean was sparked by a deadly combination of warm water and over-abundance of fish.

But not all species of salmon suffered equally.

“Harvests of each species of Pacific salmon declined 35 percent, on average, in 2020 when compared with the previous 10-year average,” Greg Ruggerone, James Irvine and Brendan Conners wrote in a technical report prepared for the North Pacific Anadromous Fish Commission. “(But) harvests of Chinook salmon in 2020 were the lowest on record since 1925, declining 54 percent compared with the previous ten years.”

The scientists outlined much of the report to the Commission during a virtual meeting in June, but the official document adds some new details. 

Overall, sockeye salmon harvests declined only 10 percent in 2020, the Pacific Northwest-based scientists said, but they added that the percentage decline was distorted by a huge harvest in Alaska’s Bristol Bay.

“…Bristol Bay, in the southeastern Bering Sea, remained robust and offset the
exceptionally low harvests of sockeye salmon in the Gulf of Alaska, British Columbia, Washington, and the Columbia River,” they wrote.

The fabled Copper River sockeye run was a bust in 2020, and the return to Cook Inlet was 38 percent below the 20-year average.

Fight for survival

Sockeye heading into the Gulf face more competition from pink salmon than do sockeye from Bristol Bay, and pinks are now the dominant species in the ocean.

“Overall, pink salmon represented approximately 74 percent of total salmon abundance in 2018/2019,” the researchers reported to the Salmon Commission, an international entity. “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.”

Pinks pushed the ocean’s all-salmon abundance off the charts in 2015. In a peer-reviewed study published in Marine and Coastal Fisheries: Dynamics, Management, and Ecosystem Science in 2018, Ruggerone and Irvine reported that 90 years of salmon-harvest data showed salmon more abundant then than at any time in history. 

The study did not mention “global warming,” but did observe that “since the 1977 ocean regime shift (to warmer waters), oceanographic conditions have been most favorable for pink salmon, chum salmon, and sockeye salmon in northern regions where many large salmon populations occur in relatively intact habitats.

“In contrast, many southern natural-origin populations along both (the U.S. and Asia) continents have been more adversely influenced by habitat degradation, ocean conditions, interactions with hatchery salmon, and overharvest in mixed-stock fisheries, resulting in abundance declines. In particular, we note that abundances of natural-origin Chinook salmon, coho salmon, and steelhead in the eastern North Pacific Ocean, including Alaska, and cherry salmon in Asia have declined over time.”

Still, the trend of overall abundance continued in general through the end of the 2010s.

Numbers peaked “in 2018 when approximately 950 million pink, chum, and sockeye salmon returned from the ocean,” the new technical assessment notes. “In 2019, salmon abundance remained exceptionally high ( approximately 854 million salmon). Together the
2018/2019 period was the highest two-year period of salmon abundance on record since 1925, nearly 20 percent greater than the previous two-year high in 2009/2010, and more than 3.2 times higher than average abundance during relatively low salmon production years from 1960 to 1975” when the North Pacific was dominated by cold water.

Unfortunately, this level of production – driven in part by hatchery fish – proved unsustainable. The scientists said it appears productivity hit a “tipping point” preceding the big crash of 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,” the technical report said. “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.

“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.”

Nature at work

The hypothesis mirrors what has happened to some wildlife populations managed to achieve maximum numbers.

“Consider a population near or at ecological carrying capacity (K). Intraspecific competition would be intense, per capita forage availability low, and nutritional condition poor. Under such circumstances, even a winter of moderate severity would be capable of causing high overwinter mortality,” researchers from Idaho State University, the California Department of Fish and Wildlife, the University of Nevada-Reno and the University of Wyoming observed in paper prepared for the Eastern Sierra Center for Applied Population Ecology.

They cited a predator-control study of Dall sheep in Alaska that found that the removal of wolves and coyotes from a small area in the Wrangell St. Elias National Park and Preserve significantly increased the number of sheep there.

When there followed a severe winter with a lot of snow, warm weather and crusting that made it hard for sheep to get food, however, the big population in the area where predators had been removed crashed while the smaller population in an adjacent control area remained stable.

One of the researchers involved in that study was a member of the Boone and Crockett Club, an avid hunting group. It observed on its website that “while predator control may result in an increase in prey populations, wildlife managers and predator control advocates have to consider not only the actual effects of predation on ungulate populations, but also habitat conditions, especially in relation to carrying capacity, and weather patterns, to avoid unintended consequences.”

Alaska, with its wildly varying weather patterns, has been something of a poster child for the dangers of trying to manage big game at absolute maximum carrying capacities. Historically, this has exacerbated winter kills by creating situations that crowd too many animals onto two little range when snows pile unusually deep.

A growing number of fisheries biologists are starting to believe the same sort of thing can happen in the ocean although the complicated ocean ecosystem makes it hard to prove, a fact that has been pointed out by Bill Templin, the Alaska Department of Fish and Game’s chief “salmon fishery scientist” and a defender of commercial-fishermen controlled hatcheries engaged in massive free-range production of pink salmon in the Pacific.

Big business

The hatcheries, primarily in Prince William Sound and on Kodiak Island, have been hugely successful. They this year rebounded nicely from the 2020 crash with Fish and Game crediting the Sound hatcheries for a harvest of about 51 million pinks and Kodiak hatcheries for another 14 million.

Fish and Game has yet to summarize the statewide, pink-salmon hatchery catch for the season, but it is expected to comprise more than 40 percent of the 161 million pinks that accounted for about 69 percent of the entire, statewide salmon harvest, reported by the agency.

The big harvest – about double that of the 34 million salmon bust of 2020 – was the good news. The bad news was that all those pinks – a small, mild-tasting fish – accounted for but 28 percent of the value of the statewide salmon catch.

Pinks are the smallest and shortest-lived of Alaska’s five species of salmon. Statewide, hatcheries pumped about 983 million of them into the ocean in the spring of 2020, according to Fish and Game. 

Whatever happened to the ocean range the year before was apparently over and repairing itself by the time they hit their main feeding grounds. A Fish and Game summary of the Sound season this year cited strong returns of wild pinks as well as hatchery pinks although it is never quite clear in that area what fish are truly wild and what are hatchery strays.

Still, the agency called the returns to the Sound’s streams and rivers “encouraging given that wild fish were from the parent year in 2019 when spawners returned to dewatered streams amid a record-setting drought.”

That year was the hottest in Alaska history, and the news was full of stories about spawning salmon being cooked alive in overheated streams. “The water is so hot in Alaska it’s killing large numbers of salmon,” CNN reported at the time.

The long-term consequences, at least for pinks, appear to have been minimal.

“Alaska and Russia pink salmon abundances appear to have rebounded to the exceptionally high values in 2019,” Ruggerone reported to the Commission. “Sockeye salmon returning to Bristol Bay, Alaska, set a new record high in 2021 (66 million fish), apparently in response to favorable early marine growth in the Bering Sea and relatively few maturing pink salmon in 2020. In contrast, commercial harvests of (longer-lived) Chinook, coho, chum, and sockeye salmon remain somewhat low in many regions of Alaska and Russia.”

That ‘tipping point’

They said their hypothesis that heat and an over-abundance of pinks pushed salmon to a “tipping point” in 2020 is buttressed by a 2020 peer-reviewed study in the Canadian Journal of Fisheries and Aquatic Sciences that “found that a 1.5-degree Centigrade increase in sea surface temperature was associated with a 23 percent increase in sockeye productivity in the Bering Sea, a 9 percent  productivity increase in the Gulf of Alaska, but with a 12 percent decline in productivity in the southern region (British Columbia and Southeast Alaska).”

That study, however, focused on water temperature changes from 1976 to 2009 when the northern Gulf of Alaska was still considerably cooler than in the mid-2010s. It is probable the northward movement of warm water in the 2010s years was responsible for the record increases in Bristol Bay sockeye at the expense of sockeye in the Gulf along with those in  Southeast and British Columbia.

As for the explosion of pinks, which appear to enjoy a warm-water advantage, the Canadian study examining ocean warming, “also reported that a 119 million increase in pink salmon abundance was historically associated with a 9 percent decline in sockeye productivity in the Bering Sea and the Gulf of Alaska, and a 21 percent decline in British Columbia.

“This finding is consistent with the (theory of a) trophic cascade caused by abundant pink salmon and other studies indicating adverse effects of pink salmon on the growth, age-at-maturation, survival, and abundance of sockeye salmon, Chinook salmon, coho salmon, chum salmon, marine fishes, seabirds, and potentially southern resident killer whales.

“Support for the adverse interaction between pink salmon and other marine species is strengthened by biennial patterns in marine species that are consistent with the biennial pattern in pink salmon in most years; these biennial patterns cannot be explained by physical oceanography. The adverse effect of numerous pink salmon on vital rates of other salmon species is far-reaching because salmon are known to migrate thousands of kilometers at sea.”

Actually proving this to be the case is, however, hard as Templin has noted.

And thus, the scientists told the Salmon Commission that “further evaluation of 2021 and 2022 harvests and returns of Chinook, coho,

chum, pink, and sockeye salmon are needed to evaluate the validity of our tipping point hypothesis.”


















20 replies »

  1. The real question here is Bristol Bay sockeye production is at record levels likely impart the fact that cold winters helped outmigration survival/ timing while Gulf of Alaska was still plagued by the remanace of the Blob.
    Global warming may be in fact favoring Being Sea Production. In fact high Bristol Bay prodution of sockeye had been known to negatively affect oven migration of Yukon/Kuskokwim Chum due to predation/out competition.
    Regardless, the idea that Pinks are outcompeting coho and Chinook is rediculous. Its hard not to assume much of this speculation is agenda based science.

    • Interesting Ty that you use “Global Warming” and “Its hard not to assume much of this speculation is agenda based science” together in your comment. Just had to chuckle.

      • Possibly my point is lost in traslation that global warming could be benificial to salmon on the northern tier of thier range. Interestingly Bristol Bay has such a diverse of sockeye watersheds for these exact kinds of conditions vs other watersheds in the state that either are hit or miss.
        Overall inland salmon populations saw the biggest impacts from the drastically warmer then normal temperatures vs Bristol Bay that had a much greater marine influence.
        Alaska is quite possibly experiencing the coldest winter with the most snow in over 5 decades. This will only bose well for salmon survivals throughout the state.

    • Ackshually, the long term UW fisheries monitoring in the Wood Tikchik system has shown that the shorter winter seasons / longer summers have warmed the water temperatures enough in that massive freshwater rearing environment so that many more sockeye fry and smolt survive, and outmigrate to salt water. Whereas before they was not a lot sockeye production from the Wood Tikchik system (compared to the other major drainages) because the water temps were too low, now those temps are high enough so as yo not be a limiting factor. This accounts for much of the increase overall in Bristol Bay abundance of sockeye returns. So the initial saltwater smolt survival rates have not increased dramatically, the number of outmigrating smolts have from the Wood Tikchik system.

      If you have ever flown over the Wood Tikchik system, you have an idea of how much more freshwater habitat is now available for juvenile sockeye production.

  2. Questions Worth Considering Concerning Hatchery Salmon Releases

    I found the following questions submitted by an individual to the Prince William Sound / Upper Copper River Board of Fisheries meeting of profound interest:

    How can hatchery fish help wild fish?
    Is there an ecological niche for hatchery fish? Don’t hatchery fish swim with wild fish? Don’t hatchery fish compete directly with wild fish for the space and food needed to grow and survive to reproduce? Don’t hatchery fish stray and spawn with wild fish? Don’t wild fish turn into wild/hatchery hybrids the first years of hatchery strays? Is biodiversity enhanced by having thousands of wild populations in all the run or a handful of release groups in most of the run? How can the fitness of these hybrids be better than that of locally adapted interbreeding wild fish? Don’t wild salmon help nurture their offspring with their marine/carcass-derived nutrients? Perhaps wild salmon spawning and dying by the millions in thousands of natal streams is key to sustaining the productivity of our watersheds and estuaries? Isn’t the abundance of salmon (and all biota) limited more by the environment’s carrying capacity than by the numbers of young? Can you think of an animal, or plant, or microbe on Earth whose productivity and abundance is limited more by reproductive capacity than carrying capacity? Would you agree that carrying capacity trumps reproductive capacity for all biota? How can there be a big open niche in the environment for hatchery fish that is not already filled by other fish? Why would we think that the ocean is limitless and that all we need to do is release little ones to harvest more big ones? Doesn’t the releasing and harvesting of hatchery salmon result in nutrient mining and ecological overshoot? Perhaps we are just letting millions of hatchery fish join in the ecosystem potluck without bringing a dish? Shouldn’t we assume that if we want to harvest more fish then we need to maintain the spawners (fertilizers)? How can doing something so different from nature in nature be better than nature? Where have we done so without unintended consequences? Where on Earth has the free-range ranching of livestock that mine more nutrients than they recycle proven sustainable, ecologically sound, and profitable? Where do we have production hatchery releases and not declining or depressed ‘wild’ runs of eulachon, herring, or salmon? Why would we assume that hatcheries are supplementing rather than supplanting wild salmon? Just because thousands return to where they were released? Why disregard the State’s wild stock priority and precautionary principle? Why should hatcheries be allowed and encouraged to release super-sized fish so they will have a survival advantage over wild fish? Why spend money to make fish when nature will make more for free? Shouldn’t management focus on maintaining quality spawning, rearing, and migration habitats and quality distribution and abundance of wild spawners. How could there be a sustainable economic niche for hatchery fish if there is not an ecologic one? What do we want – hatchery jobs and hatchery harvesters or healthy stocks and healthy fisheries? How will it be possible to rebuild and sustain wild stock escapements and returns with ongoing production hatchery introductions?

    • Andy: As far as I can tell, the idea that hatcheries are supplementing wild production is now almost wholly and solely (given the historically high numbers of salmon in the North Pacific these days) based on the idea that ocean productivity is limitless. A first-year ecology student learns that there are no ecosystems in which productivity is limitless, but that seems to be the case here.

      The thinking goes so like this:

      “The ocean covers so much space and wild salmon occupy so little of that space that we can throw loads of hatchery salmon into the empty space and make a lot of money without hurting anything!”

      It’s an idea that would merit serious thought if hatchery salmon. could be trained to eat different prey than wild salmon.

      • Craig, Are you stating that a first year ecology student, upon learning that no ecosystem has limitless productivity might, just might believe that some ecosystems such as Skilak and Tustemena lake escapement levels are possibly exceeding escapements that provide maximum productivity. Or to put another way- overescapement?

      • well, my first question as an ecologist would be this: maximum productivity for what and/or whom? i’d suspect, for instance, that over-escaping sockeye into those two systems might be reducing productivity for moose and commercial fishermen while increasing productivity for rainbow trout and sport fishermen.

        to start with.

        there are also all sorts of other players involved. ecosystems with a wide variety of predators and prey are complicated. they are also, sadly, rarely considered from an ecosystem standpoint. people lose sight of reality and want everything managed for MSY, but that’s an ecological impossibility.

        or at least an ecological impossibility in natural ecosystem. now farms, which create their own carefully controlled ecosystems free of most wild things, can be managed for MSY. wheat farmers manage for MSY. the ecological costs to nature are huge, but the wheat feeds the nation.

  3. Those in the know, and who forecast such things expect another Bristol Bay record breaking return. ADF&G predicts 75 million while the University of Washington is predicting 71.9 million.

    • Bristol Bay sockeye smolt appear to have a size and possible timing advantage over humpies. It will be interesting to see if that lasts with humpy numbers increasing in the Bering Sea. Or if the falling PDO cools the Bay down and the benefits of global warming start to fade for a while.

  4. But, “correlation is not causation “. A quote from ADF&G Bill Templin that will go down in Alaska fisheries management history as one of the dumbest things ever said.

    • There is more actual data and research supporting the notion that an overabundance of hatchery pink fry released into PWS destroying red, coho, king and chum runs than there is supporting the notion that Pebble will destroy all fish in Bristol Bay instantly and for all time. Yet we are moving Heaven and earth to stop Pebble while whistling past the wanton destruction of other salmon species in PWS. Time for fish farming for pinks. Sooner would be better than later. Cheers –

      • Alaska is already fish farming pinks. The only difference between what we do here and what the Norwegians do there is that we call the farming “ranching” and avoid the use of pens. But it’s every bit as much farming as the cattle roaming the pastures of the West.

    • In Templin’s defense, he was right in the statement that correlation is not causation. The problem is that in science correlation is cause for investigation to find out of it is or isn’t a causative factor. Where Templin fell on his face was in suggesting the situation is too complicated for ADF*G biologists to investigate and thus they were/are just going to assume all is fine. There’s an old saying about ass-u-me.

      • Craig, of course it’s not wrong too make that statement by itself. But considering all the information that Templin had that pointed towards a problem with putting so many millions of hatchery fish in the same ocean with wild stocks, the prudent thing and what is required by Alaska regulations would have been to take a precautionary approach rather than dismiss it by his correlation vs causation comment. Regrettably, fisheries politics and not conservation seem to rule the day far to often.

  5. Thanks for all that. Hatcheries are at tipping point. The only issue I have with report is it fails to clarify “wild pinks” in PWS when we have ample ADFG data that hatchery pinks are abundant in wild streams in PWS and have “imposed” significantly on wild stocks. This continues to seriously threaten genetic diversity in wild stocks. I doubt that gene pool has survived hatchery overproduction. So all pink salmon from PWS are hatchery pinks with a very tiny percentage still holding all their wild genes.

      • The “average maximum” for a warm-water phase in the GOA was 7.9M from 1938 to 1947.

        It is interesting that when the topic of PWS humpy production was debated in the late 1990s, the argument of hatchery supporters was an economic one (not a biological one) based on the idea you could farm salmon without damaging wild stocks:

        “In the quarter century before the hatchery program, the annual harvest of pink salmon was never above 8 million, and there were 5 years in which managers closed fisheries to conserve spawning stocks: 1954, 1955, 1959, 1972, and 1974 (Koernig and Noerenberg 1976). Since 1980, when appreciable harvest of hatchery stocks began, the harvest has not been below 8 million, and there have been at least 2 years in which hatchery stocks sustained the harvest: 1988 and 1992 (Sharp et al. 1996). It may well be that the 25 years preceding the hatchery program were characterized by climatic conditions that produced low marine survival of pink salmon in the northeast Pacific Ocean and that the years
        since have been characterized by good climatic conditions and high marine survival (Hare and Francis 1995). That is, much of the relatively high production may be attributable to a shift of the marine climate rather than to the hatchery program. However, the PWS hatchery program was not developed to ameliorate poor marine survival of pink salmon. Rather, it was developed to ameliorate limitations of the freshwater environment, specifically the extreme mortality associated with winter dessication and freezing of incubating pink salmon embryos (Koernig and Noerenberg 1976). Arguably, the PWS hatchery program has been successful in that goal: harvests have increased, and harvests have been possible in years when wild stocks were necessarily protected from harvest.”

  6. At the recent BOF meeting in Cordova all attending had their rose colored glasses on. No changes and not much in the way of opposition. We are watching a slow motion train wreck. Where is the Wild salmon Center? Where are the conservation groups?

    • The Wild Salmon Center and the conservation groups appear to be in an unholy alliance with commercial fishermen to stop Bristol Bay, stop logging in the Tongass National Forest, and maintain the pressure to tear down dams in the West. Every indication I get is that the latter might be the most important. They are afraid that if factors other than dams are identified as helping to depress salmon numbers, they will lose political leverage. It’s a damn sad (or is that dam sad) state of affairs.

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