Warming Temperatures Spell
by Associated Press
NEWPORT, Ore. -– Herb Goblirsch is not sure whether he believes in global warming, but he has no doubt his ability to make a living as a fisherman can turn on a difference of just a few degrees in water temperature.
“The ocean was like a desert,’’ Goblirsch recalled of the El Nino that warmed ocean temperatures off Oregon in 1982 and 1983. “The salmon we were catching were long and skinny, like a northern pike. When I saw fish that should have dressed out at 17 pounds dressing out at 11 pounds and going into the medium pile, I said, ‘That’s it. I’ll give the fish a break.’’’
Climate changes are no stranger to commercial fishermen. El Nino generated warmer waters in 1982-83 and again in 1997, bringing a host of warm-water species that were caught off Oregon. Scientists have also seen changes in migrations of some species of krill, the tiny zooplankton at the foundation of the food web.
“There are a lot of things that haven’t been seen before,’’ said Bob Francis, a professor in the University of Washington School of Aquatic and Fisheries Sciences. “But whether that’s due to global warming or not, people don’t know. Because nobody has that kind of perspective.’’
As an in-between zone, the West Coast does not have as much physical evidence as the Arctic and tropics to point to global warming, said Nate Mantua, a research scientist with the University of Washington Climate Impacts Group in Seattle. In the Arctic, for example, pack ice is thinning. In the tropics, coral reefs are being bleached. Both can be linked to warmer water.
One new source of evidence for the waters of the Northwest lies in the shells of geoduck clams, said Mantua.
Research published in March in the journal Geophysical Research Letters showed growth rings on geoduck clam shells could be used to track coastal water temperatures.
Using clams from the Strait of Juan de Fuca, between Washington and Vancouver Island, B.C., that lived as much as 160 years, the authors found the 1990s to be the warmest decade for summertime water temperatures there since the 1850s. They hope to push the record back even farther by digging for the shells of long-dead clams buried in sediments.
What is better known is that the atmospheric conditions known as El Nino, based in the southern Pacific, and the Pacific Decadal Oscillation, based in the northern Pacific, drive climate in the West, in the ocean as well as on land.
Between them, they can swing coastal ocean temperatures as much as 10 degrees Fahrenheit, making it practically impossible to see the 1- to 3-degree increase ascribed to global warming, said Mantua.
The ocean-warming El Ninos may offer a preview of what to expect from global warming, said William Pearcy, professor emeritus of oceanography at Oregon State University.
Pearcy compiled a list of warm-water species not normally seen this far north that were caught off Oregon in the 1997 El Nino. They include California barracuda, dorado, striped marlin, yellowtail, yellowfin tuna and jumbo squid. The squid were abundant again last summer.
“Those are El Nino events which may or may not be linked to global warming,’’ he said. “Certainly you can use what happens in an El Nino event as an indication of what may be happening with long-term global warming. If you have increased temperatures, you will have different species up here. And that will not be good news for salmonids.’’
El Ninos have meant less food for salmon in the ocean and more warm-water predators such as jack mackerel and whiting to eat them when they migrate out of their native rivers to the ocean. On land, warming climate predictions generally call for less snowpack in the mountains, which means lower and warmer summertime flows in the rivers where salmon spawn and spend up to a year before heading to sea.
“So it’s a double whammy,’’ Pearcy said.
A flip in the Pacific Decadal Oscillation in 1998 is widely considered responsible for the current upsurge in salmon runs because it cooled the ocean and generated winds that churned the water so that nutrients settled on the bottom were drawn up, feeding plankton that are the foundation of the food chain.
Bill Peterson, an oceanographer with NOAA Fisheries in Newport, is watching the Pacific Decadal Oscillation for signs of global warming.
Identified only 10 years ago, the PDO is like El Nino in that it goes through phases that produce colder and warmer ocean waters and changes weather patterns. But the PDO’s phases are longer – 20 to 23 years, compared with three to seven years for El Nino.
The PDO apparently flipped from warm phase to cool phase in 1998 – a judgment scientists are still trying to confirm. In the past, flipping to the cool phase has meant colder waters and northerly winds producing good upwelling from the Gulf of Alaska down past Oregon into the California Current, and warmer waters in the Bering Sea. That translates into lots of food and good returns for Northwest salmon, and less food and poorer returns for Alaskan salmon. When the PDO is in the warm phase, Alaskan sockeye salmon traditionally thrive while Northwest salmon starve.
But this time, the water wasn’t as cold as in 1977, Peterson said. The winds didn’t shift the same way, either. After getting warmer as in the past, the Bering Sea turned cold last winter.
“That’s what confuses people,’’ Peterson said. “We’re not getting this pattern of 20 years one way vs. 20 years another way.
“It is much more subtle issues and important issues than whether the ocean is warmer by 1 degree,’’ Peterson added. “How fast are currents flowing? What does the community of animals look like? What are the nutrient concentrations in deep water that you can hope to upwell and cause production?’’
After the PDO shift, more than just salmon rebounded, Peterson said. Groundfish, a broad group of fish including rockfish and ling cod whose numbers crashed precipitously, had their first good spawning season in years in 1999.
“I don’t think we know where we are headed with this other than that it’s going to shift (fish) communities to the north,’’ Peterson said. “That’s what’s predicted to happen with land communities, too.’’
The impacts can be huge, economically as well as ecologically. Whiting, for example, is a huge fishery that produces the raw material for imitation crab, known as surimi. If it moves north with warming waters, it will move into Canadian waters, out of reach of the American fleet. If the whiting pass the Oregon Coast when young salmon are emerging from their native streams, their feeding could produce major losses for salmon fishermen.
Scientists are just beginning to look for ways to translate what they know about climate and the ocean into long-range predictions to help fisheries managers set harvests.
Whatever happens, Goblirsch expects fishermen will follow the fish, the way they always have.
“A lot of fishermen moved to Alaska during the El Nino years and made their fortunes,’’ he said. “If we have to move, we will.’’
University of Washington Climate Impacts Group: tao.atmos.washington.edu/PNWimpacts/
NOAA Global and Climate Change Program: www.ogp.noaa.gov
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