Distribution and Survival of Adult Hatchery Spring Chinook Salmon Radio-Tagged and Released Upstream of Warm Springs National Fish Hatchery in 2008. Progress Report

摘要

The Warm Springs River supports the largest population of wild spring Chinook salmon Oncorhynchus tshawytscha in the Deschutes River Basin. Located on the Warm Springs River in north-central Oregon, the Warm Springs National Fish Hatchery was constructed in 1978 and produces spring Chinook salmon for sport and tribal harvests. Current hatchery practices intend to minimize disturbance to upstream wild fish populations by limiting the number of hatchery fish passed upstream. Concerns over the low numbers of wild fish returns, increasing pre-spawning mortality, and significant reductions in wild genetic integration into hatchery broodstock have led to inquiry over the fate of spring Chinook salmon passed above Warm Springs National Fish Hatchery. Increasing the number of hatchery fish allowed upstream of the hatchery has been suggested as a potential management action to compensate for the low wild fish numbers. The ecological and genetic consequences of this potential management action are currently unknown. To gain further insight on these management concerns, 35 hatchery-origin spring Chinook salmon were radio-tagged during the spring and summer of 2008 and released upstream of the hatchery to study their movement patterns, identify potential holding areas, estimate survival, and approximate their contribution to spawning.