he 1958 creature feature The Blob ends (spoiler alert for a movie older than Alaska statehood) with the titular monster frozen in its slimy tracks and airlifted to the North Pole, not dead but at least defeated. “As long as the Arctic stays cold,” quips Steve McQueen’s character. Well, about that….
A blob menaced the Gulf of Alaska in recent years, and the marine ecosystem has yet to fully recover. The Blob is what researchers called the warm water anomaly that persisted in the region from 2014 to 2016. The event was followed by several smaller warm water anomalies in subsequent years. While some elements of the ecosystem have returned to pre-Blob levels, marine heatwaves that triggered the event are expected to increase in severity, duration, and frequency, with unknown consequences for the North Pacific food web and Alaska fisheries.
The Blob was tied to huge seabird die-offs, whale mortality events, and declines in fish populations, such as Pacific cod and Chinook salmon, explains Rob Suryan, the Recruitment, Energetics, and Coastal Assessment Program Manager at NOAA’s Alaska Fisheries Science Center.
“The Gulf seems to be in an alternative state at this point,” Suryan says. “It hasn’t fully recovered to pre-heatwave conditions, and it’s not in what we’ve seen in prior conditions, but that doesn’t say it still won’t.”
Because the Gulf of Alaska is an enormous region—591,900 square surface miles—the metrics of recovery look very different at the Western Gulf near the Alaska Peninsula, across to Cook Inlet, Prince William Sound, and even Southeast Alaska.
“There are some examples where physical and biological metrics have returned back to baseline, but there are others that have not,” Suryan says.
The waters around the Kenai Peninsula, stretching to the Copper River Delta, continue to suffer from a more sustained impact from The Blob than much of the rest of the region.
“The heatwave was very unique, at least in our hindcast, in the sense that it was a multi-year event in which many organisms were affected by warm temperatures,” says Russell Hopcroft, chair of the Department of Oceanography at UAF. “And it was not just the summers; these were temperatures that stayed persistent in the system even during the winters.”
“You’re going to see winners and losers as the climate changes,” Hopcroft says. “Some species lose and some species that used to be minor components in the ecosystem do well—and depending on their economic value, we as a society make a decision on whether that’s better or worse.”
For example, if an ecological regime shift in the Gulf of Alaska suddenly drops the salmon and pollock fisheries to historic lows but, at the same time, Albacore tuna increases, is that a better or worse system? From an economic point of view, Hopcroft says, the answer depends on tuna harvests and how they help balance the books.
However, warmer waters are generally less productive. A large part of this is because the warmer the water, the less dissolved oxygen it can hold. Most fish are cold blooded, so in warmer waters they must use more energy for respiration.
“That means a bigger percentage of your food goes to those basic costs of living processes and less of it is available for making you grow,” Hopcroft says.
Because of The Blob, much of the productivity of the Gulf of Alaska collapsed in 2015, says Nate Mantua, the leader of the salmon ecology team at NOAA’s Southwest Fisheries Science Center.
“That’s why you saw things like the Pacific cod stock have a recruitment failure,” Mantua explains, “and maybe even lost older-aged animals because there just wasn’t a lot of food, and warmer water increases the metabolic rates for cold-water fish, so they need to eat more than they did in a cold year.”
Not only does warm water require most species targeted by the Alaska commercial fishing fleet to spend more energy foraging—potentially increasing the amount of time they are targeted by other predators—but it also limits the amount of food available in the food web.
“The water column needs to be mixed because nutrients that promote phytoplankton growth near the surface [where sunlight penetrates] become depleted, and there are more nutrients down below,” Suryan says.
Warming in the Gulf of Alaska hampers mixing in the water column by creating more freshwater from glacial melt and increased rainfall, which is lighter than saltwater, causing it to stay near the surface.
“More freshwater helps strengthen that stratification, making it more difficult to break down,” Suryan says. “Heatwaves also warm the surface waters and can create a stronger, stratified water column… Increased water column stratification is one of the predictions of global warming.”
“We also see a lot of year-to-year variation because of changes in wind and weather patterns and ocean currents,” Mantua says, noting that within the last six months there has been at least temporary cooling within a few hundred miles of shore.
“The temperatures have dropped a lot from where they were from the 2014 to 2021 period… It’s not clear how long that’ll last,” he says.
While nearshore marine ecosystems are getting relief from rising water temperatures, offshore waters have not followed suit.
“The North Pacific as a whole is exceptionally warm,” Mantua says. “There is a broad area south of the Aleutians and far offshore where the highest number of marine heatwave events have been.”
These offshore areas are important feeding zones for salmon from all around the Pacific, as well as for steelhead trout.
“Persistent marine heatwaves have been frequent and disruptive to marine life and fisheries in the North Pacific. Especially in the last eight, nine years,” Mantua says.
NOAA Fisheries has numerous recent fishery disaster declarations related to these heatwaves, with six of the eight recent ones connected to Gulf of Alaska fish stocks. These included Copper River Chinook and sockeye salmon fisheries in 2018 and in 2020, Prince William Sound salmon fisheries in 2020, and Pacific cod in 2020.
“Helping communities to bounce back from the impacts of fishery disasters is essential, and we are working to ensure there is relief coming for impacted Alaskans,” says US Secretary of Commerce Gina M. Raimondo. “Disasters like these, which impact multiple fisheries across Alaska, illustrate how vital sustainable fisheries are to our economy at not only the local level but for the economic health of our nation’s blue economy.”
“The amount of heat that’s in the oceans has been increasing. It’s one of the really clear indications of global warming,” Mantua says. “Ninety percent of the excess heat trapped by the atmosphere, because of the increasing strength of the greenhouse effect, is ending up in the ocean.”
Hopcroft points out that, according to nearly all published literature about marine heatwaves, the increase in magnitude and frequency is a direct consequence of anthropogenic causes—that is, humans.
“We’re going to see our cold, icy waters of the Gulf of Alaska become more like what we see in the Lower 48,” Hopcroft says.
While a single marine heatwave is unlikely to shake up in the food web to the scale that it would be considered a regime shift, more persistent changes in the frequency of the events could spark the change.
“Every critter in the ocean is playing this game of eat or be eaten—grow fast to get out of these windows where they’re somebody else’s food,” Mantua says.
In a regime shift, who is best at the game changes dramatically, reshuffling various levels of the food web.
“The energy in the system is just going to go through different paths,” Mantua explains.
Suryan notes that during The Blob it was very clear that the energy in the Gulf of Alaska system was not being transmitted to the upper trophic levels, when big critters eat smaller critters.
The Blob led to a decline in krill, capelin, and sand lance—three major forage species for transmitting energy up the food chain.
“That’s a pathway that’s important for predators, including salmon, sea birds, and mammals,” Mantua says.
Lack of energy making it to these top predators can lead to mortality events and, in the case of salmon, smaller fish returning to spawn, which could affect the tonnage of the commercial harvest and therefore the value of the fishery.
NOAA Fisheries
NOAA Fisheries
“With Alaska fisheries being wild-capture only by law, they are always going to be subject to environmental impacts,” says John Burrows, the seafood technical director at ASMI. “The state and federal authorities managing these fisheries monitor a wide variety of environmental variables, and they are paying increasing attention to these temperature trends. For them, well-being of the fisheries is a top concern, but the health of the ecosystem and species is the priority.”
When there is a regime change, very little can be done but adapt. It’s happened before: prior to the ‘70s, the Gulf of Alaska harvest was dominated by shrimp and bottom feeding fish. That all changed, and fishermen were forced to change with it. One of the major theories for the cause of the ‘70s regime change was that more food was staying higher up in the water column instead of ending up on the seafloor, favoring salmon and other midwater fishes.
“It’s poorly understood because we didn’t have enough of these long-term observation programs in place at the time,” Mantua says. “Scientists are inherently cautious about trying to talk about a system changing until it’s pretty black and white. We can expect that things are going to be changing and maybe changing more rapidly in the future than what we’ve seen in the past.”
In the movie The Blob, the final image is the words “The End” changing into a question mark. Uncertainty likewise surrounds the North Pacific blob: Where did it come from? Will it happen again? What will survive? Can it be stopped? Forewarned by the first Blob, researchers now know what to watch for, just in case of a sequel. 