[5] Some Northwest Salmon Runs Fizzle, Others OK
Poor ocean conditions are getting more blame than dams as more Northwest salmon runs are showing up far short of expectations.
The first case in point--the early sockeye run on B.C.'s famous and undammed Fraser River--was originally estimated from fry abundance to come in around 260,000 fish, but showed so poorly by early July that Canadian biologists downgraded it to a mere 35,000 fish.
A July 15 press release from the Pacific Salmon Commission said "the cause of this very low return is presently unknown; however, adverse marine survival conditions may have persisted through a portion of their marine residence period."
Since then, more sockeye have appeared in test fishing and the run has been bumped back up to better than half (185,000) of the preseason estimate. But the commission said the late run and the fact that fewer sockeye are diverting around Vancouver Island than they had anticipated, is making accurate estimates difficult.
As for the spring chinook returns to the Fraser, Pacific Salmon Commission biologist Mike LaPointe told NW Fishletter that test fishing has pointed to the lowest numbers in 25 years, about 20 percent of average.
Further south, the sockeye appear to be mainly no-shows. Lake Washington's urban sockeye run, which travels through metropolitan Seattle on its way to the Cedar River at the south end of the lake, has been a dismal failure this year. By July 26, only 67,000 fish had been counted at the Ballard locks, about 300,000 less than last year's count at this time. State and tribal biologists had expected about 400,000 to show this year. They blame a hot ocean and predators for the big decline.
A report issued by Canada's Department of Fisheries and Oceans attributed the summer warming to "abnormal weather in British Columbia and the Gulf of Alaska, as well as to general warming of the global lands and oceans."
Jumbo flying squid showed up off Vancouver Island last fall.
(Courtesy of DFO)
It went on to say that "Other findings showed global land and ocean temperatures were near a record high in 2004. This same weather in B.C. brought record high temperatures to the Fraser River, which was a contributing factor to the low sockeye spawning numbers observed in 2004."
The report also catalogued some recent changes.
Low-oxygen waters at 200 meters depth or more crept toward the B.C. coast from mid-Gulf of Alaska.
Hake were sighted in Dixon Entrance, at the International Boundary between Alaska and Canada, much farther north than in 2003.
Southern species of zooplankton increased in abundance and dominant northern oceanic zooplankton species bloomed earlier in spring.
Cold water species such as shrimp declined in numbers off Vancouver Island.
For the first time, an exotic (Atlantic origin) zooplankton species Acartia tonsa successfully invaded B.C. waters on the open continental shelf.
Many jumbo squid were observed in B.C. and Alaska, a first for this warm water species.
Herring presented a mixed response to warming.
The news was better in the Columbia River, after a spring chinook run showed up about one-third the size that harvest biologists had anticipated. The basin's upper Columbia sockeye were tracking close to preseason expectations of around 70,000 fish. By July 26, more than 72,000 had been counted at Bonneville Dam. Tribal fishers caught about 3,000 of them, along with close to 8,000 summer chinook--another run that was coming in close to predictions.
Harvest managers were relieved that the summer runs were tracking better than the springers in their models, but they had few answers to the poor showing of spring chinook. Some other runs seemed adversely affected by ocean conditions as well. By July 25, about 35,000 chinook had been counted at Oregon's Willamette Falls, about half of what was estimated preseason for the Willamette River run.
Hatchery returns for spring chinook also were down considerably. Bill Thorson, who manages the Carson National Fish Hatchery, just upriver of Bonneville Dam, said the hatchery was close to its projected egg take, with 1,140 fish returning so far. Thorson said another 1,200 hatchery chinook had been landed in the nearby Wind River sport fishery, and about 400 more were caught by tribal fishers. But the return to the hatchery is far below recent years, when 8,000 to 12,000 fish showed up.
The 2005 return is close to 1998 numbers, when only 0.36 percent of the outmigrants returned. When numbers began to shoot up in 2000, the managers estimated the smolt-to-adult return rate had nearly quadrupled. And it went up from there. A Fish Passage Center study on hatchery fish survival has estimated that 3.2 percent of the 1999 outmigration from Carson returned to Bonneville Dam. This is less than the 3.5 percent SAR for the barged McCall hatchery fish from Idaho, which must swim about 250 miles farther upstream and pass seven more dams before they are counted.
National Marine Fisheries Service scientists sent a memo in late May to regional NMFS administrator Bob Lohn that speculated on the poor showing of spring chinook in the Columbia River. They said less plankton, more fish predators and warmer water had created a less favorable near-ocean environment for salmon in 2003 than the previous four to five years, but not bad enough for them to expect the extremely low survivals in 2005.
"It remains possible that the low returns this year resulted from significant mortality in an area of the ocean that we are currently not evaluating," they said, noting that they don't know where the upper Columbia springers feed in the ocean.
But they did report that several important indicators of ocean conditions had switched to a negative direction from the previous few years when spring chinook returns jumped an order of magnitude. These signals included the Aleutian Low Pressure Index, which showed its second largest value in the past 45 years.
Better news on the river's fall chinook may be coming soon. These fish spend much of their ocean lives in places known to biologists and show up in fisheries from Alaska to Oregon, as do the summer chinook from the upper Columbia, which have returned at numbers close to estimates.
Regional harvest managers have pegged the Columbia fall run at 671,000 fish, down from last year's 799,000 fish. Nearly 500,000 of them are estimated to be headed above Bonneville Dam, with the upriver bright component aiming for the Hanford Reach expected to be the fourth largest return since 1964. -B. R.
The following links were mentioned in this story:
2004 Pacific Region State of the Ocean
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