Yakama Nation Columbia River Basin Predation II

Anthropogenic impacts to the Columbia River and its tributaries have altered the habitats and environment to favor many species of salmon predators. These predators include piscivorous colonial waterbirds (e.g. California gull, Ring-billed gull, American white pelican, Double-crested Cormorant) and native and non-native predatory fish species (e.g. Northern Pikeminnow, Smallmouth Bass, Walleye, Channel Catfish).



We recognize that predation is a keystone agent that controls fish population dynamics. Although predation can be a naturally occurring control mechanism for fish populations, predation management is needed in altered system like the Columbia River. Research over the last three decades has shown an alarming increase in predation on salmonids. As part of the commitment of the Yakama Nation to honor, protect, and restore our sacred fish and water resources, we are proposing to implement solutions that will result in the efficient reduction in predator populations in key locations to increase survival of our salmon and steelhead.



Worksite #1 Proposed Work:

Miller Rocks Islands in The Dalles Reservoir – Avian dissuasion and depredation activities under this proposal will occur at and around Miller Rocks Islands with the objective of eliminating California gulls, Ring-billed gulls, and other colonial water birds from colonizing and breeding on this culturally and environmentally sensitive area.



Worksite #2 Proposed Work:

Lower/Middle Yakima River – Within five reaches of the Yakima River and taken 12-15 weeks during the salmon smolt migration, we will lethally removed 180 American white pelicans annually for three year and analyze diet composition. Arial flights will be conducted to determine pelican abundance and distribution within the Yakima River to help focus future efforts.



Worksite #3 Proposed Work:

Klickitat River Delta – We plan to provide additional support for predator removal a variety of methods including bank and boat based hook and line sampling and/or seining and electrofishing. This support may include planning, permitting and on the ground removal efforts building on ongoing work to investigate species composition, abundance and distribution in the lower Klickitat River delta focusing on predator species both native and non-native.

Avian predation is one of the largest sources of hydro-system mortality for juvenile steelhead and Chinook salmon (Evans et al., 2022). In 2021, the predation/consumption rate of juvenile Upper Columbia River steelhead and Snake River sockeye at Miller Rocks alone was 12.4% and 13.9% respectively (Evans et al., 2022). Estimates of smolt consumption rates by gulls nesting at Miller Rocks in The Dalles Reservoir were the highest of any colony evaluated in 2021 (Evans et al., 2022), yet the Miller Rocks gull colony and most colonial waterbird populations are currently unmanaged. Miller Rocks is located within the Yakama Nation Territories and was created by the construction of the Dalles Dam. Miller Rocks is a culturally important location for the Yakama Nation Tribal members; reducing the gull colony and the associated impacts on migrating juvenile salmon and steelhead is a top priority for the Yakama Nation.



The American white pelican population within the Columbia River basin established in the early 1990s and has growth exponentially since colonizing on Badger Island. This population is also currently unmanaged and is directly responsible for significant impacts to Yakima river salmon smolts. Our most recent PIT tag data revealed similar counts of Yakima River PIT-tagged Coho, Fall Chinook, and Spring Chinook detected at McNary Dam as Badger Island, and Summer Chinook PIT tags recovered at Badger Island actually exceeded the count of PIT-tagged fish detected at McNary (Pandit, unpublished). These numbers are strictly raw numbers and do not account for detection efficiencies at the dam or island, however indicate that pelican predation impacts our salmon population



These extremely high consumption rates or gulls at Miller Rocks and pelicans in the Yakima River result in a direct economic loss to tribal fishers as salmon numbers are reduced by bird predation. The total economic loss to tribal members is not easily quantified, but the loss and ability to fish at usual and accustomed places due to bird predation is a cultural loss that is far greater than its economic value.



Predator dissuasion and removal has a demonstrated effect on reducing predation rates and increasing survival of salmon and steelhead smolts. Given the high predation rates in these locations we would expect to see a commensurate increase in salmon survival from the Yakima River to McNary dam and within the Dalles reservoir in the Columbia River in direct response to the actions for which we are seeking funding.



Predation by non-native invasive piscine predators (e.g. smallmouth bass, walleye) similarly has disproportional impacts on rearing and migrating salmon stocks in the Columba River. Habitat changes in the Columbia River associated with hydroelectric impoundments have altered the riverine habitat into a series of lacustrine systems creating areas that are now more suitable for both native predators. Increasing water temperature as a result of climate change has also allowed piscine predators to expand their range into critical salmon rearing habits.



The Yakama Nation has documented disproportionality low survival rates of salmon and steelhead in the lower 1.5 km of the Klickitat River (Romero and Kuhn, 2021). Water velocities through this reach are drastically reduced by backwater effects which in turn increase smolt travel time and greatly increased predation risk and vulnerability to piscivorous predators (Rieman et al., 1991). After fish composition and abundance data is collected in the lower Klickitat River delta and reservoir influenced reaches, we can assess potential predation impacts on salmonid species and inform managers decisions on how to improve survival of juvenile salmon migrating from the Klickitat River into the Columbia and managing these piscivorous fish species.