An Investigation of the Relationship Between Oregon Coho Salmon (Oncorhynchus kisutch) Hatchery Releases and Adult Production Utilizing Law of the Minimum Regression

Abstract

This study examines aggregate relationships between coho salmon (Oncorhynchus kisutch) adult production and hatchery releases within the Oregon Index Area (OIA). Previous analyses have indicated the presence of density dependence, and concluded with a request for a reduction in hatchery smolt releases. The hypothesis that density dependence is exhibited in the OIA is tested via a broad correlation approach. Several regression models are used including one unique one in fisheries research based on limiting factors.Analysis was done on the fitted regression equations including a simple simulation of release policies. Neither significant density dependence nor a statistically supportable technical maximum for smolt releases was found. The limiting factors regression technique generally gives the best results of all the models employed, and thus appears potentially useful in this type of fisheries work.