[env-trinity] Salmon Runs Small

Tue Oct 30 10:08:12 PDT 2007

Are they late or missing?

SALMON RUNS:

Central Valley salmon largely absent from fall run - but why?

San Francisco Chronicle – 10/30/07

By Jane Lay, staff writer

This year's Central Valley fall salmon run is worrying both fishermen and biologists, who say fewer of the prized chinook are out in the ocean or making it up the rivers to spawn.

By this time, usually tens of thousands more fish are being hooked by fishermen or are swimming through the Golden Gate to the tributaries of San Francisco Bay. Upstream, the fish spawn in the same rivers where they were born, carrying on the generations of silvery king salmon.

Yet commercial fishermen who hunt for salmon in the ocean from Monterey to Bodega before the fish start their journey up the rivers report the worst salmon fishing in decades.

Fisheries biologists in Northern California who count the salmon that return up the American, Feather and Sacramento rivers are seeing a big decline in fish for this time of year. Some runs might have as few as 20 to 25 percent of the fish normally expected by this time of year, data show.

The salmon run could just be a little late this year, say state Fish and Game Department officials. On the Klamath and Trinity river systems, biologists say the salmon are about three to four weeks late, but they think the fish will come eventually.

The exact cause of the apparent drop in fall-run salmon is not yet clear, although some experts blame the way the state manages its water supply in the Sacramento-San Joaquin River Delta. Rushes of fresh water can signal fish to start migrating upstream, but meager flows also can hurt the survival of baby fish that eventually will return as adults. Low levels of krill, tiny marine invertebrates that the fish eat, also could be to blame, experts said.

In tributaries like Battle Creek, an important salmon spawning ground off the Sacramento River, there is cause for concern. By now, about three-quarters of the fall run would have passed by the weir where Fish and Game officials count the fish. Usually, the creek's run is between 50,000 and 100,000 fish at this time; so far, there have only been 20,000 spawning chinook, said Randy Benthin, a senior fisheries biologist for Fish and Game. 

And on the Yuba River, only 54 salmon have returned so far, down from a total of 3,842 fish in 2003. The Feather River has one-third of the fish it usually has at this time of year, according to state statistics.

The Pacific Fishery Management Council, a regulatory body that sets limits on commercial fishing, had predicted a lackluster year for the Central Valley fall run. Of the four runs in the bay, the fall run is the largest. Fish and Game has set a goal of 120,000 to 180,000 spawning fish every fall, and in recent years has met that goal.

Zeke Grader, executive director of the Pacific Coast Federation of Fishermen's Associations, said the low fish counts are particularly worrisome because of the extra limits placed on fishing in recent years. Those limits were specifically aimed at boosting the number of fish that return to spawn on the Klamath River.

He blamed problems with moving water around the delta. The lack of krill in the ocean may have exacerbated the meager runs, he said.

The Sonoma County Water Agency, which this summer urged growers and residents to cut water use by 20 percent due to dry conditions, issued a statement Monday decrying the dearth of salmon returning to the Russian River, which depends on flows from the Eel River.

"Right now by this time in the year, we should have about 500 fish" passing the counting equipment at Forestville. "In our best year (of record keeping), we had 2,500 at this point. Just now we're just over 100," said Sean White, a county fisheries biologist.

The water agency is concerned that people are fishing at the mouth of the Russian River, capturing the few fish that are heading up to spawn.

Seabird expert Bill Sydeman, who recently founded the Farallon Institute for Advanced Ecosystem Research in Petaluma, said he is working on models that link seabird health with abundance of the salmon. The fish and birds feed on krill, lots of zooplankton and young rockfish attracted by nutrient-rich waters.

The conditions that salmon face in their first and second years have a bearing on whether they live to spawn at age 3.

Krill numbers were lower in 2006 and 2005 than they had been in 2001 and 2002, for example, Sydeman said. "It's not surprising to me that there are low salmon returns in 2007."

Oceanographers at the National Oceanic and Atmospheric Administration have been studying ocean conditions for decades. They link good years for salmon with vigorous upwelling of cold, deep, nutrient-rich water to the ocean's surface and the influx of cold Alaskan waters that bring in krill and other sea life.

This year the upwelling and transport of cold Alaskan waters were strong. Then the mixing slowed down. The surface water has been warmer than usual in the California Current, the swath of water moving between Baja California and British Columbia, and it can hold down the upwelling, the scientists say. And scientists report a relatively poor year for California and Oregon salmon.

"We're trying to understand what's going on out there," said Frank Schwing, an oceanographer with NOAA's Southwest Fisheries Science Center in La Jolla (San Diego County).

The scientists are trying to figure out whether there is a regime of cold and then warmer-water decades - or whether global warming could be throwing off the predicted regimes.

"One of the ideas is that global climate change will introduce greater extremes and much more variability into the climate. In reality, it's going to take a couple of decades. Then we can look back and see what the patterns were," Schwing said. #

http://www.sfgate.com/cgi-bin/article.cgi?file=/c/a/2007/10/30/MNAAT2VTR.DTL

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