Upper Yakima Bull Trout Restoration and Monitoring Project

Project abstract:

What We Know About Upper Yakima Bull Trout Populations: Isolated populations of bull trout living in the Upper Yakima Basin face significant challenges such as blocks to adult migration, degraded instream habitats, and invasive species. Sensitive to warming temperatures, they are also increasingly challenged by a changing climate. As a result, Yakima Basin bull trout populations currently consist of low numbers of adult spawners. Extreme seasonal dewatering presents an additional challenge, resulting in frequent stranding and desiccation of juveniles. The Yakama Nation's Yakima Basin Bull Trout Restoration and Monitoring Project currently consists of two phases, Phase I is considered a life boat strategy. The process of juvenile capture, rearing and release needed to be proven before additional phases could be implemented. Phase II consists of rearing and releasing bull trout into tributaries that offer hope for self- sustainability. These new populations may prove vital in buffering the Yakima Basin population from extinction.

During Phase 1 of the project, conducted during 2019, Yakama Nation Fisheries (YNF) was assisted by Washington Department of Fish and Wildlife (WDFW) in expanding current rescue operations in Gold Creek and the Upper Kachess River. YNF finalized permitting and initiated captive rearing, releasing fish back into their native reservoir habitats. YNF also installed and operated PIT (passive integrated transponder) tag arrays to monitor fish movement, and assisted WDFW with annual redd surveys. PIT tag arrays are receivers that help our biologists to monitor tagged fish over time to determine movement, survival, and spawning success. Focal areas for monitoring include Gold Creek, the Upper Kachess River, and Box Canyon Creek.

During Phase 2, YNF has been planning our expanded project implementation and obtaining permits to reintroduce bull trout back into their historic habitats, utilizing the South Fork Tieton River as a potential donor population. Our biologists have also been working on a pilot study to eradicate brook trout (a non-native invasive competitor and hybridizer with bull trout) using YY-male technology, which negatively impacts brook trout reproductive success.

Funding for this project is secured through the Yakima Basin Integrated Plan (YBIP) and provided by the U.S. Bureau of Reclamation and Washington State Department of Ecology. In addition to the YNF staff listed, recognition is due to Richard Visser, Reseach Scientist with the U.S. Bureau of Reclamation, and Jeff Tayer, former WDFW Region 3 Director, for their contributions to the project.

Project goals:

Goals for this project include increasing current bull trout population size and range by rescuing stranded juvenile bull trout during low water conditions, rearing the juveniles for up to 1 year to increase survivability, and reintroducing the reared fish back into good quality historic habitats, thus reducing future losses and increasing natural reproductive potential. In addition, deleterious genetic and competitive impacts to the populations will be diminished by reducing or eliminating brook trout and hybrid populations.

Captive rearing goals include rescuing, transporting, and rearing up to 1,250 young of the year bull trout from each population each year, rearing them for up to 1 year on a natural diet and in 55 degree well water, and releasing the juveniles when they are approximately 150mm in length. During captivity they are tested for genetic diversity, fitness, and potential diseases, and they are tagged prior to release in June-August each year. The captive bull trout diet consists of daphnia, brine shrimp, mysid shrimp, blood worms, and salmon or trout fry.

Project plan:

Currently, the Yakama Nation is working in coordination with Bull Trout partners WDFW and USFWS to formulate a 10 year vison. This vision will include expanding “life boating” populations, and beginning the supplementation and reintroduction of Bull Trout below the reservoirs. Permitting is scheduled to begin in late winter 2022, and reintroductions to begin in 2024.

Project progress:

Bull Trout Life Boat Strategy 2020-2021

Bull Trout captive rearing operations were extremely successful during this performance period. By using adaptive management, survival was increased significantly from the 2019-2020 rearing cycle. Gold Creek survival was 98% (up from 74%), with 63 released into Keechelus Reservoir. Kachess River survival was 89% (up from 14%) with 531 released into Kachess Reservoir. All fish were PIT tagged and length, weight, and DNA were collected. Acoustic tags and/or Pinger tags were surgically implanted in the largest fish from each population (11 Gold Creek & 24 Kachess River) by the USFWS to monitor movement and behavior throughout Kachess and Keechelus Reservoirs.

Bull Trout rescue and transport operations for the 2021-2022 rearing cycle were also successful during this performance period. A total of 87 YOY were rescued from Gold Creek in August and are currently rearing at LaSalle with zero mortality to date. A total of 471 YOY were rescued from the Kachess River during the same time period and successfully transferred to LaSalle. Only 3 mortalities have been documented in the Kachess population since they arrived. We did not meet the goal of transporting 600 Kachess YOY to LaSalle due to the lack of YOY present. This is likely a result of the low redd counts (approx. 2) observed in Fall 2020. Both populations are currently growing at the same rate as the previous rearing cycle.

See this article on the Bull Trout Project in The Daily Record (Feb. 6, 2021): Bull trout reintroduction project aims to reinvigorate species in Upper Yakima Basin

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