Hatchery Contribution to a Natural Population of Chinook in the Hanford Reach of the Columbia River, Washington
This paper is an attempt to quantify the contribution of Priest Rapids Hatchery to the productivity of Upriver Bright stocks in the Hanford Reach natural production area. Analysis of coded-wire tag recoveries from approximately 200,000 Upriver Bright fall chinook reared at Priest Rapids Hatchery (Oncorhynchus tshawytscha), marked annually since 1973, indicates a significant contribution to the natural spawning on the Hanford Reach. The population structure of returning runs, escapement estimates, number of hatchery smolts released, number of hatchery smolts marked with coded-wire tags, returning hatchery fish, and coded-wire tag (CWT) recoveries were evaluated to estimate natural production of smolts and the proportion of natural production attributable to hatchery progeny. It was found that on average 29.83% of the Priest Rapids Hatchery returns spawn on the Hanford Reach, and that hatchery-reared fish contribute up to 33.05% of adult returns to the Hanford Reach spawning grounds in any one year, averaging 8.63% over the 20 years surveyed. Our results show that fisheries managers should consider the potential for hatchery-reared fish to contribute to the productivity of natural stocks in the development of recovery goals and management practices, and that the fraction of the returning population from the hatchery must be considered when estimating natural population parameters.
Evenson, D.F., D.R. Hatch, and A.J. Talbot. 2002. Hatchery Contribution to a Natural Population of Chinook in the Hanford Reach of the Columbia River. Columbia River Inter-Tribal Fish Commission Technical Report 02-03, Portland, Oregon. 13p.