GRANTS PASS, Ore. — Commercial salmon fishermen in Oregon and California are seeking federal disaster assistance because of sharp reductions in fishing seasons they blame on continuing water problems in the Klamath Basin.

Claiming commercial salmon trollers from Santa Cruz, Calif., to Florence, Ore., could lose up to $100 million from lost fishing opportunities this summer, the Pacific Coast Federation of Fishermen's Associations has called on the governors of California and Oregon to support a fisheries disaster declaration from NOAA Fisheries.

"This is a disaster of federal making, caused by a policy of letting too little water remain in the Klamath River," said Glen Spain of the federation representing about 2,000 boats, most of them from California. "We may be facing future fisheries disasters for the same reasons."

California Department of Fish and Game biologists have said the likely cause of the low returns this year is the increasing number of young fish succumbing to parasites as they migrate to the ocean. Some scientists think the parasites may be proliferating because low wintertime flows no longer flush them from the river.

Predictions call for plentiful returns of Sacramento River chinook this year, but trollers will not be able to fully exploit them over concerns that too many Klamath River fish swimming among them could be taken.

Last week, the Pacific Fishery Management Council set ocean salmon-fishing seasons sharply shorter than last year to be sure that a mandated 35,000 chinook return to the Klamath River to spawn. Last year, fishing seasons resulted in missing the mark by 10,000 fish.

Farmers, fishermen, Indian tribes and conservation groups in the Klamath Basin have been battling to win a larger share of limited water supplies since 2001, when the bureau cut off water to most of the 1,400 farms on the irrigation project during a drought to meet Endangered Species Act (ESA) mandates for fish.

Irrigation was restored the following year, but untold thousands of juvenile fish died migrating to the ocean and more than 30,000 adults died after returning to the river and succumbing to gill-rot diseases in low, warm-water conditions. Since then, the U.S. Department of Interior has arranged extra cold-water releases from the Trinity River, a Klamath tributary, to help returning adult salmon travel up the lower Klamath.

Facing a drought this year, the U.S. Bureau of Reclamation has reduced water deliveries to farms in the Klamath Reclamation Project as well as flows down the Klamath River for threatened coho salmon.

While the bureau maintains it is meeting ESA mandates for coho, fishermen complain the flows continue to be far below target levels that must be met by 2010 to have any hope of restoring healthy returns of chinook and coho.

NOAA Fisheries, the federal agency that oversees ocean fishing, is in the first stages of seeing whether losses suffered by salmon fishermen qualify for a disaster declaration under the Magnuson-Stevens Act, which governs ocean fishing, said agency spokesman Jim Milbury.

A disaster declaration would qualify fishermen and others for long-term, low-interest loans and other assistance programs, Spain said.

Oregon Gov. Ted Kulongoski is looking into the matter, said spokeswoman Anna Richter Taylor. There was no immediate response from the office of California Gov. Arnold Schwarzenegger.

The basin has struggled with dwindling salmon returns for more than 20 years related to loss of habitat to agriculture, hydroelectric dams, logging and mining. Disasters were declared during an El Niño in 1982-1983 and during an extended drought in the late 1980s and early 1990s.