Effects of water temperature and flow on adult salmon migration swim speed and delay
adult, migration, salmon, chinook, steelhead, Columbia River, transponder, upstream, Lower Granite Dam, dams, models
Journal or Book Title
Transactions of the American Fisheries Society
The effects of temperature and flow on the migration of adult Chinook salmon(Oncorhynchus tshawytscha) and steelhead (O. mykiss) through the Columbia River hydrosystemwere determined with a novel technique that fits a broken linear model of swim speed versustemperature and flow by partitioning data into speed ranks. Using the migration times of passiveintegrated transponder (PIT)-tagged adult Chinook salmon upstream between Bonneville andLower Granite dams (462 km) over the years 1998-2002, we found that a maximum swim speedof about 1 body length/s occurred at 16.38ºC. Speed was less above and below this optimumtemperature. For PIT-tagged steelhead, migration speed uniformly decreased with increasingtemperature, suggesting that the fish migrated at temperatures above the optimum. Migrationdelay was also a unimodal function of temperature, the minimum delay occurring around 16-178ºC. The broken linear model was compared with seven alternative models of unimodal andmonotonic speed versus temperature and flow. The unimodal models fit the data better than themonotonic models (when ranked by the Akaike information criterion), and the broken linear modelfit the data best. Flow was insignificant in all of the monotonic models and only marginallysignificant in the unimodal models. The findings of this study have significance in evaluating theeffects of hydrosystem operations and climate change on salmon and steelhead fitness.