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Biologists look to ocean for clues in Alaska king salmon collapse

Craig Medred
Courtesy Todd Hardesty

What scientists know about the working of the ecosystem beneath the storm-swept waters of Alaska is a lot and almost nothing. Because for all that is known, no one has a clue as to the latest fishery mystery that has so many in the 49th state talking: Where have all the king salmon gone?

"Gone to graveyards everyone," to quote the old song "Where Have All the Flowers Gone?" Well, not quite every king is gone to the graveyards, but a bunch of them clearly left Alaska rivers as young fish never to return. This is known from the work of state fisheries biologists who track spawning numbers and monitor smolt migrations.

"We're adequately seeding the spawning grounds," said Jeff Regnart, director of the Alaska Department of Fish and Game's Division of Commercial Fisheries, "but they're not coming back."

What both state and federal fisheries biologists studying in Alaska have seen, in general, is good numbers of king salmon on spawning beds followed by good numbers of smolt going to sea. Smolt are young king salmon. The salmon lifecycle is a bit complicated: Adult fish bury eggs in gravel. Over winter, the eggs hatch into alevins that live in the gravel. By spring, the alevins are ready to wiggle out of the river bottom as fry. The fry begin feeding on various forms of insects and crustaceans. Young kings will do this for one or two summers, depending on the river system, before they began to "smolt up" as fisheries biologists like to stay.

Smolting is a physiological process that adapts the body of young salmon to life at sea. Gills and kidneys adapted to life in freshwater need to change to be able to function in saltwater. There's a thorough outline of the entire life cycle, here.

Smolting is so stressful it can contribute to the death of some fish, but then a lot of things can kill small fish in freshwater. Fry in Alaska streams are subject to predation by all sorts of birds and other fish, from rainbow trout to northern pike. More salmon will die young in Alaska streams, in fact, than will die anywhere. Some studies have concluded that only about 20 percent of the alevins emerge from the gravel as fry. They then face a tough life. Most fry are doomed.

Various studies have calculated that 92 to 96 percent of the young salmon spawned in Alaska streams never see the ocean. If even 10 percent of the king salmon eggs deposited in an Alaska stream live to become smolts headed to sea, that survival rate would be considered phenomenal. The number of survivors usually numbers far less. Still, millions of king smolts make their way to saltwater each year.

Missing Anchor River kings

A study commissioned by the U.S. Fish and Wildlife Service on the Anchor River, a small stream near the southern tip of the Kenai Peninsula, estimated 75,000 smolts left that one little stream in 2011. If Alaska was witnessing the sort of ocean survival seen back in the 1990s, about 4,500 of those smolts would be expected to return as adults. If Alaska were to see the sort of survival rate witnessed by Washington and British Columbia hatcheries in the mid-70s -- when they averaged 11 percent -- more than 8,000 kings would return.

State fisheries biologists figure they need a minimum of 3,800 spawners to seed the Anchor. A return of 4,500 would provide about 700 fish for anglers. A return of 8,000 and anglers would be in fat city. But 8,000 doesn't seem likely. The Anchor closed to fishing almost as soon as it opened this year. Only 3,455 kings reached the river's spawning grounds in 2009. The next year was better with 4,417, but there were only 3,547 last year despite the early closure of the stream to all fishing. Instead of a 6 or 7 percent return adults to smolts, there was a return of less than 5 percent. This year could be worse.

So what happened?

Pretty clearly something went wrong in the ocean where those Anchor kings spend anywhere from one to four years growing before returning to spawn. And this is where things get complicated. The ocean is a big, mysterious place where creatures eat each other or compete for food. Regnart conceded it could take a long time to try to figure out all the interactions in the ocean, but he would like to see the state get started on the research.

"We're going to get engaged to the best of our ability," he said, "but it will come down to dollars."

Given enough money and time, there is no doubt researchers can figure out more about the interactions of marine fish, their various prey and the diseases to which fish are prone in the ocean off Alaska, but even if researchers start to get a handle on how things work, there are big questions as to their ability to manipulate it. Freshwater management is relatively easy. Biologists make sure fishermen -- commercial, subsistence and sport -- let adequate numbers of salmon survive to spawn and let nature take it from there, although they once did more.

Killing char and eagles

Back in the bad old days, when federal officials managed fisheries in Alaska, there were bounties on Dolly Varden char and eagles -- the former because they eat salmon eggs and the latter because they eat salmon. And fishermen were encouraged to shoot bears and seals, two well-known salmon predators. Eventually, scientists concluded that none of these wild predators were really killing enough salmon to make a difference at the population level. Thus the bounties came to an end and attitudes toward bears and seals began changing.

The good thing about the bad old days was that humans could at least see the predator eating salmon or salmon eggs. Humans could identify a problem even if it wasn't "the" problem. This isn't nearly so easy in the ocean where everything happens beneath the water and the list of predators is exhaustive. Here is just a partial list of fish known to eat some salmon: hake, mackerel, ling cod, pacific ocean perch, other salmon, halibut, cod, pollock, greenling, and sculpin.

And those are just the fish. There are also birds and marine mammals preying on salmon.

Maverick researcher Donald Dobbs counted at least 137 predators that could have a significant impact on ocean salmon survival and posited the question: "Should predators be ignored?" He went on to summarize the kill from seven known predators as somewhere near 230 million salmon per year, with a total kill by predators near 500 million. Dobbs once headed a contrarian consultancy called "North Pacific Research" he used to lobby for marine predator control.

What about bycatch?

No one else has suggested such an idea unless, of course, one accepts humans as the supreme predator in the North Pacific. Scientists, fishermen of all stripes and environmentalists have all pushed to reduce human predation in the form of the incidental catch of salmon, especially kings, in the nets of the trawlers that strip mine the seas off the coast. There is no doubt that this catch -- called "bycatch" in the commercial fishery -- is wasteful. By law, bycatch is thrown back into the sea dead or donated to food banks to prevent trawlers trying to profit off it.

Various interest groups reacted angrily when the bycatch of kings hit a peak of 122,000 in the Bering Sea in 2007. The North Pacific Fisheries Management Council -- a government entity largely controlled by commercial fishing interests -- soon bowed to public pressure to do something. Trawlers were in 2009 put under a bycatch cap of 60,000 kings in the Bering Sea. They are required to quit fishing if that cap is reached.

The Bering Sea trawl fleet is primarily after pollock, the main ingredient in fish sticks and other processed fish products. The fleet catches about 1.3 million metric tons per year. Pollock are the backbone of the largest food-fish business in the country. Pollock trawlers contend they prosecute one of "cleanest" fisheries in the world, though there are many who have taken issue with that. The Alaska Marine Conservation Council celebrated when the North Pacific Council followed the Bering Sea bycatch cap with a 25,000 king quota for trawlers in the Gulf of Alaska.

"Alaska’s valuable runs of king salmon from the Copper River to Cook Inlet and Kodiak have been suffering over past years with sport, subsistence and commercial fishermen facing restrictions due to ailing populations," the conservation group reported. "At the same time these salmon stakeholders have been feeling the pinch, by-catch of our prized king salmon soared to over 51,000 in the Gulf of Alaska. This all-time high number reinvigorated a call from the Alaska Marine Conservation Council, coastal Alaskans and federal fishery managers to halt “the unacceptable level of waste and put in place the first ever hard cap on king salmon bycatch in the Gulf trawl fisheries."

Many have made the link between high bycatch of kings and low returns to Alaska waters, but there is scant evidence of a cause-and-effect relationship. The 51,000 kings caught as bycatch in the Gulf in 2010 is only a fraction of the number of kings that leave the Anchor River -- one tiny Alaska stream -- bound for the Gulf each year. And an Alaska state study in 2002 estimated that an average 30,000 king salmon bycatch in the Bering Sea trawl fisheries reduced the Western Alaska king return by "less than 2.7 percent." The study indicates the record catch of 122,000 kings in 2007 would have put an 11 percent dent in the return of kings to the Yukon, Kuskokwim and other rivers.

Far greater numbers than that are missing. Some have suggested bycatch in the trawl fisheries could be grossly under reported. "Over a dozen crew members of the inshore fleet have commented that over the last decade the salmon bycatch is under-reported by an average of 40 percent (range of under-reporting was stated as between 20 and 70 percent)," the U.S. Federal Register, a regulatory document, recorded. The National Oceanic and Atmospheric Administration, which was at the time proposing new regulations on trawlers, responded by saying it was getting observers on board all trawl vessels to ensure accurate counts on salmon, halibut and other by-catch.

Something else happening at sea?

But even a 70 percent undercount of the record Bering Sea catch of 122,000 kings would be only 207,400 kings, accounting for -- if the state's 2002 estimates of bycatch impact are accurate -- a less than 19 percent reduction in returns to Western Alaska streams. Various genetic studies have pegged about 25 percent of the trawl catch as Yukon River kings. Thus, in a worst case scenario, the trawl fleet could be responsible for a Yukon River reduction of about 52,000 king salmon.

Between 1982 and 1996, the Yukon saw an average of more than 300,000 kings.

Chop 52,000 kings off a run of 300,000, and there should still be some 248,000 kings left. There aren't. The Yukon king return this year, according to Fish and Game estimates, could fall below 110,000 fish, the pre-season estimate. Easy though it might be to blame the trawlers for all of the missing salmon, there are indications of other factors at play.

Bycatch also triggers a revealing question that needs to be asked:

If Alaska king returns are suffering because of the trawlers, why are Pacific Northwest salmon, which feed in the Gulf of Alaska and Bering Sea before running a gauntlet of Alaska and Canadian fishermen on their way home, doing so well? Returns are booming in rivers from the California border north to Canada. Salmon advocates are predictably claiming credit for the turnaround from the days of bust. The Associated Press reported the big Northwest returns "were hailed both by conservationists and fishermen who’ve struggled against drought, endangered habitats and water-diversion projects that have taken river water from spawning routes for agriculture and reservoirs."

All of those things are important to salmon. There is no doubt about that, but as Alaska, with its millions and millions of acres of pristine salmon habitat, appears to be illustrating, there is more to the equation than humans can control. What happens out of sight, beneath the seas and largely beyond the control of people, plays a huge role. The Northwest Fisheries Science Center, a NOAA think tank, hints Mother Nature remains most influential over salmon returns. The center notes something called the Pacific Decadal Oscillation paints an interesting picture about salmon survival in the North Pacific Ocean.

See-saw with Pacific Northwest

The Pacific oscillation is a pattern of variation in ocean water temperatures. Researchers found that if they compared the cool phases and the warm phases of the Pacific oscillation to salmon returns in Alaska and the Pacific Northwest, a correlation jumps out.

"Nathan Mantua and his colleagues were the first to show that adult salmon catches in the Northeast Pacific were correlated with the Pacific Decadal Oscillation (Mantua et al. 1997). They noted that in the Pacific Northwest, the cool (Pacific oscillation) years of 1947–1976 coincided with high returns of chinook (king) and coho (silver) salmon to Oregon rivers. Conversely, during the warm (Pacific oscillation) cycle that followed (1977–1998), salmon numbers declined steadily," the science center reported.

When the king returns to Oregon rivers went up, Alaska returns dipped. When the Pacific oscillation cycled into a warmer phase, both trends responded: Oregon returns went down, Alaska trends went up, and more than one state fisheries biologist was heard to mumble, "Thank you global warming."

Now, despite global warming, the Pacific oscillation is sliding back into a cool phase, which is not a good thing for Alaska. When the Pacific oscillation slipped briefly back into the cold zone in the late 1990s, the state's most valuable return of salmon -- Bristol Bay sockeyes -- went temporarily bust. Given the Pacific oscillation track record, some officials are already starting to worry that the worst thing about the bad king returns this year might not be the low number of kings but the possibility this is a harbinger of what is about to happen to many Alaska salmon runs.

Historic shortages

There are precedents. Failures of salmon runs in the late 1800s led missionary Sheldon Jackson to lobby Congress for help in transplanting reindeer to the north to feed Alaska residents. The state was then home to fewer than 65,000 people -- about two thirds the number now living in the Fairbanks North Star Borough. Fishing techniques were primitive. It is hard to believe man was having a huge impact on the resource at the time, and yet there were few fish.

In his pleas to Congress for aid, Jackson included a September 1896 letter from a missionary in Unalakleet named Alex Karlsen.

"You know, Doctor, that Unalaklik (now Unalakleet) is quite a large village, and the people here, as in most places elsewhere in the country, are depending on fish, seal and meat of land animals," Karlsen wrote. "Among land animals, the deer (caribou) is the most important, but these are now nearly extinct in this part of the country, and belong to the time past. Even the seal is not so plentiful as in former years. After deer commenced to be scarce, the people hunted the seal more than before; consequently, the seal is getting less numerous, too. Fish is therefore the most reliable food for these people. Some years the run of fish is very small ... Very few fish have been caught during the whole season, which is close to its end. It is no wonder then that the people around us anxiously ask, 'What shall we eat next winter?' They are coming to us, thinking that we are able to read this riddle."

Karlsen had no answer. More than 100 years later, there’s still no answer. Sometimes the fish do not come back simply because the fish do not always come back. Alaska has grown far more sophisticated than it was in Sheldon's day, and yet the riddle remains.

Contact Craig Medred at craig(at)alaskadispatch.com