Evaluation of Juvenile Salmonid Outmigration and Survival in the Lower Umatilla River Basin, Annual Report 2001-2002.

The year of 2002 represented the eighth year of a multi-year project, monitoring the outmigration and survival of juvenile salmonids in the lower Umatilla River. This project both supplements and complements various ongoing and completed work within the Umatilla River basin. Knowledge gained on juvenile outmigration and survival assists researchers and managers in adapting hatchery practices, flow enhancement strategies, canal and fish ladder operations, and supplementation and enhancement efforts of natural and restored fish populations. Findings from this study also assist in assessment of the success of upriver habitat improvement projects and provide an overall evaluation of the Umatilla River fisheries restoration program. General project objectives include: Evaluation of the outmigration and survival of natural and hatchery juvenile salmonids in the lower Umatilla River, in an effort to enhance the understanding of migration characteristics, survival bottlenecks, species interactions and effects of management strategies. Specific objectives for 2002 included: (1) Operation of the remote interrogation system at Three Mile Falls Dam, West Extension Canal; (2) Design of improved PIT tag detection capabilities at Three Mile Falls Dam east bank adult fish ladder; (3) Estimates of migrant abundance, migration timing and in-basin survival of tagged juvenile salmonids representing various hatchery, rearing, acclimation and release strategies; (4) Monitoring of abundance and trends in natural production of salmon, steelhead and pacific lamprey; (5) Continuation of transport evaluation studies to evaluate the relative survival between transported and nontransported fish; (6) Assessment of the condition, health, size, growth and smolt status of hatchery and natural migrants; (7) Investigation of the effects of canal and fishway operations and environmental conditions on fish migration and survival; (8) Documentation of temporal distribution and diversity of resident fish species; and (9) Participation in planning and coordination activities within the basin and dissemination of results. Key findings for 2002 revealed: (1) Migrant abundance of natural fish was roughly 10% that of hatchery produced fish; (2) An undetermined number of hatchery summer steelhead are residualizing in the upper Umatilla basin and potentially overwintering and migrating out as 2 year old smolts; (3) Transported fish may have a survival advantage over non-transported fish; (4) The later release of hatchery summer steelhead resulted in emigration timing that differed from that of naturally-produced fish; (5) Large-grade summer steelhead released lower in the river displayed improved survival over fish released higher; (6) Extended reared steelhead did not exhibit a survival advantage over standard reared fish; (7) Second year evaluation following reduction in the subyearling fall chinook program revealed survival to be similar to pre-reduction estimates; (8) Migration success was not improved nor in-river residence time reduced by acclimation of coho salmon at RM 56; (9) Early released spring chinook salmon migration and survival was unable to be evaluated due downstream monitoring facilities being in-operable during the early migration