Estimated run size of winter steelhead in Oregon coastal streams, 1980-85

Populations of winter steelhead (Oncorhynchus mykiss) exist in virtually every watershed along the Oregon coast. Actual run size of these populations are unknown. The purpose of this report is to present estimates of the run size of wild and hatchery winter steelhead in Oregon coastal streams. Fishery managers in Oregon have previously estimated run sizes of steelhead in Oregon streams. As part of a statewide fish and wildlife planning effort, begun in 1970 by the Oregon State Game Commission, a fish resource inventory was created by estimating the distribution and abundance of fish in individual streams. Passage counts, where available, were used to determine the total combined escapement in streams above the counting facility. In areas where total escapement was not counted, estimates of escapement were derived using steelhead recreational catch statistics. Estimates of the proportion of hatchery and wild stocks in the catch, and estimates of exploitation rate (25% and 50% for wild and hatchery steelhead, respectively). Spawning escapement within individual streams was apportioned using the best judgement of the district biologist. These estimates are generally referred to as the 1977 planning forms. The variable methodology used in different basins and the general lack of documentation of estimation parameters has limited the use of these planning forms. New information regarding recreational catch composition and fishery exploitation rates warrant another attempt at estimating run size. Fishery managers will be able to use this information for basin planning and the fishery management programs contained therein. (21pp.