SAN FRANCISCO—Diners: The time has come to say goodbye to low-priced salmon. This week, the Pacific Fishery Management Council, the federal agency that regulates the fishing industry on the West Coast, announced that it was canceling the entire fishing season for chinook salmon in California and Oregon, the first time the agency has taken such a step since it was established 22 years ago. The council has been wrestling since January with the mysterious disappearance of a huge number of salmon in the Sacramento River, where most of the fish on the Pacific Coast go to spawn. This fall, fewer than 70,000 fish were counted in the river, down from more than 800,000 six years ago. Experts still don't know exactly why the salmon population has dropped so precipitously, but most think it is due to a combination of temperature changes in the ocean and man-made water diversions in the Sacramento Delta. There are expected to be about 50,000 fish in the river this fall.