The Pacific Fishery Management Council meets in Seattle this week and will likely vote to impose the most severe restrictions ever on West Coast salmon fishing. Only about 90,000 adult chinook salmon returned to the Sacramento River Valley in California last fall. The number is projected to fall to a record low of 58,000 this year. By contrast, 775,000 adult chinook were counted in the Sacramento River and its tributaries as recently as 2002. The California Salmon Council has asked state and federal scientists to research 46 possible causes, including water diversions, habitat destruction, dam operations, agricultural pollution, marine predators and ocean conditions. Many fishermen and environmentalists believe the main problem lies in the Sacramento-San Joaquin Delta. They say too much water is being diverted to farms and water districts in the San Joaquin Valley and Southern California. Some scientists also point to unusual weather patterns that disrupted the marine food chain along the Pacific Coast in 2005. In that year thousands of seabirds washed up dead or starving because they couldn't find enough to eat.