Umatilla River Basin Avian and Non-Native Fish Predation II

We propose to estimate the annual impact of avian and non-native fish predators on ESA-listed Mid-Columbia River steelhead smolts and reintroduced spring Chinook salmon smolts in the Umatilla River. Continue evaluating American white pelican predation of smolts during 2024. We propose to work with non-native fish predators in subsequent years. Effects of predation on salmon and steelhead were identified as a critical uncertainty in the Columbia River Anadromous Fish Restoration Plan of the Nez Perce, Umatilla, Warms Springs, and Yakama Tribes.



Will determine if pelicans contribute significantly to the high mortality of summer steelhead smolts and spring Chinook salmon within the Umatilla River (79 river miles). A significant increase in the number of pelicans observed in the Umatilla Basin occurred after the creation of Badger Island in the Columbia River in 1993. Subsequently, the artificial island became the location of a pelican breeding colony with an estimate of 5,594 breeding pelicans in 2018.



Our original plan was to examine the stomach contents of pelicans feeding in the Umatilla River each week during the smolt migration season. The US Fish and Wildlife Service did not approve our first lethal take permit application. We submitted an updated lethal take permit application in March of 2023. The permit is not expected to be available for the 2024 field season. The collection of pelican stomachs for fish and parasite content will begin in March of 2025 at the earliest and thus is not included in this project.



In the interim, we propose to determine the deposition rates of PIT-tagged fish consumed by pelicans in the Umatilla River that are detected on the colony islands. We plan to feed 1,500 PIT-tagged fish to pelicans next spring. Five hundred PIT-tagged fish will be fed to pelicans at each of three locations (Three Mile Falls Dam, river mile 4; Westland Dam, river mile 27; Pendleton Mainstreet Bridge, river mile 53). PIT tag data detections from the bird colony islands surveys conducted by Real Time Research will be available on PTAGIS for our use by early December. We will calculate a PIT tag deposition rate by pelicans consuming fish in the Umatilla River. Combining estimates of PIT tag deposition rates, smolt tagging rates, and smolt abundance, we will estimate total consumption of hatchery and wild smolts by pelicans annually in the Umatilla River for the period of record.



We propose to document pelican’s spatial and temporal distribution in the Umatilla River throughout the year. Weekly pelican counts will be made from fixed-winged aircraft during the primary smolt out-migration periods from March through June. Monthly pelican counts will be made in the off-season (July through February). Until stomach samples are collected and analyzed, we will provide estimates of smolt consumption based on assigned ratios of 10, 50, and 90 percent to provide managers with a range of potential impacts to smolts by pelicans feeding in the Umatilla Basin.



Worksite #1 Proposed Work:



Individually feed 1500 PIT-tagged fish to pelicans during the spring of 2024 in the Umatilla River to determine the deposition rates of PIT tags on the colony islands. We propose to feed 500 PIT-tagged fish to pelicans at each of three locations listed above. Conduct weekly bird counts from the air (with GPS location) to estimate the number of pelicans using the Umatilla River for feeding and resting during the primary smolt out-migration season (March through June). Monthly bird counts will be conducted during the off-season (July through February). Use pelican counts to document their temporal and spatial distributions in the Umatilla Basin. Employ PIT tag deposition rates onto bird islands, smolt PIT tagging numbers and smolt tagging ratios to estimate the consumption of steelhead and salmon smolts by pelicans in the Umatilla River Basin.

Provide fisheries managers with empirical data regarding the impact of pelicans on smolts in the Umatilla Basin. Determine if American white pelicans contribute significantly to the high mortality of ESA-listed Mid-Columbia summer steelhead smolts and reintroduced spring Chinook salmon within the Umatilla River (79 river miles). The intent is to examine the potential impacts of pelicans on smolt survival before transitioning to examining the potential impacts of non-native predatory fish on smolt survival in subsequent years.