Snake River Fall Chinook Salmon Life History Investigations, Annual Report 2007.
- U.S. Geological Survey
- U.S. Fish and Wildlife Service
- Pacific Northwest National Laboratory
In 2007, we used radio and acoustic telemetry to evaluate the migratory behavior, survival, mortality, and delay of subyearling fall Chinook salmon in the Clearwater River and Lower Granite Reservoir. Monthly releases of radio-tagged fish ({approx}95/month) were made from May through October and releases of 122-149/month acoustic-tagged fish per month were made from August through October. We compared the size at release of our tagged fish to that which could have been obtained at the same time from in-river, beach seine collections made by the Nez Perce Tribe. Had we relied on in-river collections to obtain our fish, we would have obtained very few in June from the free-flowing river but by late July and August over 90% of collected fish in the transition zone were large enough for tagging. Detection probabilities of radio-tagged subyearlings were generally high ranging from 0.60 (SE=0.22) to 1.0 (SE=0) in the different study reaches and months. Lower detection probabilities were observed in the confluence and upper reservoir reaches where fewer fish were detected. Detection probabilities of acoustic-tagged subyearlings were also high and ranged from 0.86 (SE=0.09) to 1.0 (SE=0) in the confluence and upper reservoir reaches during August through October. Estimates of the joint probability of migration and survival generally declined in a downstream direction for fish released from June through August. Estimates were lowest in the transition zone (the lower 7 km of the Clearwater River) for the June release and lowest in the confluence area for July and August releases. The joint probability of migration and survival in these reaches was higher for the September and October releases, and were similar to those of fish released in May. Both fish weight and length at tagging were significantly correlated with the joint probability of migrating and surviving for both radio-tagged and acoustic-tagged fish. For both tag types, fish that were heavier at tagging had a higher probability of successfully passing through the confluence (P=0.0050 for radio-tagged fish; P=0.0038 for acoustic-tagged fish). Radio-tagged fish with greater weight at tagging also had a higher probability of migrating and surviving through both the lower free-flowing reach (P=0.0497) and the transition zone (P=0.0007). Downstream movement rates of radio-tagged subyearlings were highest in free-flowing reaches in every month and decreased considerably with impoundment. Movement rates were slowest in the transition zone for the June and August release groups, and in the confluence reach for the July release group. For acoustic-tagged subyearlings, the slowest movement rates through the confluence and upper reservoir reaches were observed for the September release group. Radio-tagged fish released in August showed the greatest delay in the transition zone, while acoustic-tagged fish released in September showed the greatest delay in the transition zone and confluence reaches. Across the monthly release groups from July through September, the probability of delaying in the transition zone and surviving there declined throughout the study. All monthly release groups of radio-tagged subyearlings showed evidence of mortality within the transition zone, with final estimates (across the full 45-d detection period) ranging from 0.12 (SE not available) for the May release group to 0.58 (SE = 0.06) for the June release group. The May and September release groups tended to have lower mortality in the transition zone than the June, July, and August release groups. Live fish were primarily detected away from shore in the channel, whereas all dead fish were located along shorelines with most being located in the vicinity of the Memorial Bridge and immediately upstream. During the May detection period, before the implementation of summer flow augmentation, temperatures in the Clearwater River and Snake River arms of Lower Granite Reservoir and the downstream boundary of the confluence ranged from 8 to 17 C. During the June-August detection periods, however, temperatures in the Clearwater River arm ranged from 10-16 C down to 7 m and the Snake River arm was above 20 C down to a depth of 9 m. Incomplete mixing between the two water sources resulted in significant vertical temperature variation at the downstream boundary of the confluence during a large portion of the June-August detection periods. This variation diminished during the September and October detection periods when temperatures once again fell to 17 C and lower and eventually became uniformly distributed throughout the water column in the confluence.
- Research Organization:
- Bonneville Power Administration (BPA), Portland, OR (United States)
- Sponsoring Organization:
- USDOE
- DOE Contract Number:
- 41809
- OSTI ID:
- 966362
- Report Number(s):
- P113134; R&D Project: 2002-032-00; TRN: US200921%%417
- Country of Publication:
- United States
- Language:
- English
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