Secrets of a Bountiful Seaby Brian T. Meehan
The Oregonian, May 21, 2000
Scientists are finding complex cycles at work
as nutrient-rich currents appear to be reviving ocean life off Oregon
Endangered coho and chinook in the Northwest. Gray whales off California. Seabirds in Oregon. Zooplankton, krill and shrimp off Newport. Sardines and anchovies in the Columbia River plume. Sockeye in Alaska's Bristol Bay and British Columbia's Frazier River.
Marine scientists increasingly are probing complex cycles of climate and ocean current to explain the boom and bust in these sea creatures. Ocean productivity, perhaps the least understood piece of the salmon puzzle, influences salmon, seabirds and the microscopic organisms that build the marine food chain.
Research indicates the richness of Oregon ocean waters, which sagged dramatically during the 1990s, has rebounded this spring. The ocean is set up to grow fish.
"I think all the signs are that it could be turning around," said Bob Emmett, a marine biologist with the National Marine Fisheries Service. "If anchovies come back big-time and predation drops, I think ocean salmon survival could be good. And we haven't seen much of that in a long time."
Bill Peterson, a biologist for the fisheries service, samples zooplankton off Newport as part of a coastwide research project into the California Current, the cold-water stream that flows south off the West Coast. Peterson seines and inventories the tiny plants and animals that underpin the marine food web.
This spring, Peterson found cooler surface temperatures and an abundance of plankton and krill, an important salmon food that has been scarce for years.
In the spring, prevailing winds along the Oregon coast shift from the southwest to the summer northerly. This change stirs the marine stew and benefits myriad sea creatures. The northerly breeze pushes inshore surface waters out to sea; they are replaced by cold waters that well up from the deep. This upwelling brings nutrients to the surface, spurs plankton growth and creates the subsequent marine food chain.
"Upwelling is off to a good start," Peterson said. "We had our spring transition the first week in March, which was the earliest in a long time. We've had good upwelling ever since, which is why we have krill."
Although ocean conditions favor Oregon coho, upwelling alone will not spark a sudden recovery. Biologists emphasize that dam building, freshwater habitat destruction, urban development, pollution and water diversions all limit salmon.
And this spring, the number of wild coho smolts going to sea is too slim to provoke a booming turnaround, said Pete Dawson, a research biologist with the fisheries service.
"It sounds very promising for smolts going out this year," Dawson said. "A productive ocean would be good, but we have to get some fish to go into it also."
Climate connection In the 1990s, a sequence of El Niņo s, a warming of eastern Pacific waters, wrecked the marine food chain and lured warm-water predators such as Pacific mackerel north to prey on young Northwest salmon.
Salmon runs crashed. Seabirds such as cormorants and common murres abandoned nests on the Oregon coast. Baitfish, such as northern anchovies, became scarce. For the first time in decades, sardines, which favor warmer waters, showed off northern Oregon.
Scientists studied the connections between climate and the ocean. Researchers at the University of Washington noticed a peculiar correlation between salmon catches in Alaska and Oregon. When Alaska catches peaked, Oregon catches plummeted. When Oregon soared, Alaska crashed.
The scientists, led by biologists Steven Hare and Bob Francis, linked salmon cycles to fluctuations in the strength and location of the Aleutian Low, the prevailing winter weather system in the North Pacific. The Aleutian Low influences the flow of the currents that shape ocean productivity. The scientists named the phenomenon the Pacific Decadal Oscillation, and a new way of looking at ocean and sky emerged.
The theory revealed three distinct regime shifts in the 20th century: from 1925 to 1946 when Alaska salmon boomed; from 1946 to 1976 when Northwest runs peaked; and from 1976 to the early 1990s, when Northwest stocks crashed and Alaska set record harvests.
In 1997, a powerful El Niņo further muddled the picture. The El Niņo , among the strongest on record, spoiled ocean production off Oregon and reached as far north as the Bering Sea. In the Gulf of Alaska, summer winds died, and surface temperatures warmed to record highs. A small, bony plankton boomed, turning the gulf into a turquoise sea. The meager nutritional value of this plankton, coupled with the turbidity of the green ocean, hit seabirds hard. Black-legged kittiwakes and short-tailed shearwaters, seabirds that sight-hunt, died off. The Bristol Bay sockeye run, one of Alaska's most lucrative fisheries, dropped suddenly. The 1997 catch of 12.2 million sockeye was only 40 percent of the previous year.
In 1998, Bristol Bay sockeye fell further to 10 million fish. Spooked Alaska fish managers suspected the Pacific Decadal Oscillation finally had soured northern ocean conditions. But the picture turned gray. Last year, the Bristol Bay sockeye catch rebounded to 26.1 million fish, and Alaska's overall salmon harvest reached 216.6 million, the highest since 1995.
What happened to the climate shift?
"I'm not sure anyone can peg it exactly," said Bill Heard, a research manager at the fisheries service's Auk Bay Laboratory in Alaska. "The thing about the concept of a regime shift is you can't peg it right when it happens. It's like the bottom or the peak of the stock market, you never know you were there until it stretches into the future. I think that is where we are now."
Fishery managers in British Columbia remain convinced a regime shift occurred about 1990. Coho disappeared from the Strait of Georgia. Runs of steelhead and salmon in British Columbia dropped suddenly. Pacific mackerel and sardines showed off Vancouver Island. Frasier River sockeye, a commercially important run, collapsed.
Dick Beamish, a research scientist for the Canadian Department of Fisheries and Oceans, doesn't think last year's upturn in Alaska discounts the idea of a regime shift. He thinks each climate shift begins a new period, not necessarily a return to past conditions.
"People should be careful about projecting into the future; it assumes there are only two states," he said. "Sardines disappeared off Canada in 1947. In 1977, we had a regime shift, but the sardines didn't show up. In 1989, there was another shift and sardines did show up; they skipped an oscillation."
Reading the signs What the ocean portends in the next few years is difficult to predict.
A strong La Niņa , a cooling of ocean waters, still grips the eastern Pacific. In 1999, poor conditions in Arctic waters were suspected as a culprit in a sharp increase in gray whale strandings on the West Coast. Almost 300 whales died on their migration to Mexico and back; some scientists think food shortages at summer feeding areas may have left the whales ill-prepared for their 10,000-mile odyssey.
Joe Cordaro, a federal biologist who oversees a stranding-response network in California, says gray whale beachings this spring are ahead of last year.
In Oregon, however, spring chinook returns on the Columbia River may triple the 10-year average. Although most of the fish are from hatchery stocks, the surge is an indication of a more favorable ocean.
Strong upwelling also is expected to boost the shrimp harvest off Oregon and improve nesting conditions for common murres, which congregate on coastal rocks to bear their young.
One thing for sure is that fishery managers will pay careful attention to ocean research. There are more than half a dozen large research programs examining ocean conditions between the Gulf of Alaska and Mexico.
"This work is unprecedented in 25 years," said Gregory McMurray, coordinator for the Pacific Northwest Coastal Ecosystems Regional Study, which is examining the impact of offshore conditions on Oregon estuaries.
"This work needed to be done," he said. "We didn't know what was going on in our nearshore ocean."
Beamish said managers have made big strides in understanding ocean productivity. Before, he said, managers often overlooked the wide, limitless sea.
"The ocean was so vast," he said. "We tended to see it as one homogeneous medium. ... And, of course, it isn't. The ocean has rivers and forests and deserts and things in it, too."
He said fishery managers must understand ocean cycles so they can adjust fish catches.
"The abundance of salmon is regulated in the ocean," he said. "Fresh water provides a safe refuge for salmon to reproduce, for animals that have to survive in a harsh habitat, the ocean."
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