Emigration of Natural and Hatchery Chinook Salmon and Steelhead Smolts from the Imnaha River, Oregon, 1998-1999 Annual Report.

摘要

This report summarizes the results of the Lower Snake River Compensation Plan Hatchery Evaluation Studies (LSRCP) and the Imnaha Smolt Monitoring Program (SMP) for the 1999 smolt migration from the Imnaha River, Oregon. These studies were designed and closely coordinated to provide information about juvenile natural and hatchery chinook salmon (Oncorhynchus tshawytscha) and steelhead (Oncorhynchus mykiss) biological characteristics, behavior and emigrant timing, survival, arrival timing and travel time to the Snake River dams and McNary Dam on the Columbia River. Data collected from these studies are shared with the Fish Passage Center (FPC). These data are essential to quantify smolt survival rates under the current passage conditions and to evaluate the future recovery strategies that seek to optimize smolt survival through the hydroelectric system. Information shared with the FPC assists with in-season shaping of flow and spill management requests in the Snake River reservoirs. The Bonneville Power Administration and the United States Fish and Wildlife Service contracted the Nez Perce Tribe (NPT) to monitor emigration timing and tag 21,200 emigrating natural and hatchery chinook salmon and steelhead smolts from the Imnaha River during the spring emigration period (March 1-June 15) with passive integrated transponder (PIT) tags. The completion of trapping in the spring of 1999 marked the eighth year of emigration studies on the Imnaha River and the sixth year of participating in the FPC smolt monitoring program. Monitoring and evaluation objectives were to: (1) Determine spring emigration timing of chinook salmon and steelhead smolts collected at the Imnaha River trap. (2) Evaluate effects of flow, temperature and other environmental factors on emigration timing. (3) Monitor the daily catch and biological characteristics of juvenile chinook salmon and steelhead smolts collected at the Imnaha River screw trap. (4) Determine emigration timing, travel time, and in-river survival of PIT tagged hatchery chinook salmon smolts released at the Imnaha River acclimation facility to the Imnaha River Trap. (5) Determine arrival timing, travel time and estimated survival of PIT tagged hatchery and natural chinook salmon and natural and hatchery steelhead smolts from the Imnaha River to Snake and Columbia river dams.