Bull Trout population monitoring in the Oregon portion of the mid-Columbia recovery unit

The Bull Trout recovery plan calls for the use of a threats assessment tool for evaluating the threats to the species in recovery units for 5-year status reviews and potential delisting. To some extent, those threats evaluations and status assessments will be dependent on demographic and

ecological information related to characteristics of a “recovered” recovery unit. Demographic and ecological data for most Bull Trout populations in the Oregon portion of the mid-Columbia recovery unit have not been collected consistently or extensively. A monitoring strategy for Bull Trout populations in the mid-Columbia recovery unit was recently developed (Howell et al. 2018). Our aim is to implement parts of that strategy by undertaking such activities as PIT tagging juvenile Bull Trout in rearing areas to take advantage of data generation provided by existing PIT tag detection sites downstream (e.g., in the Imnaha River), conducting electrofishing surveys to confirm results obtained from eDNA sampling efforts (presence/absence and distribution), and conducting electrofishing, snorkeling, and spawning ground surveys in streams supporting Bull Trout that are surveyed annually (abundance or relative abundance and distribution), or have not been surveyed in many years. In addition, we will participate in cooperative investigations (with the Oregon Department of Fish and Wildlife [ODFW] and Pacificorp) expanding on past work conducted in the Wallowa River drainage upstream from Wallowa Lake involving the genetic and demographic characteristics of Bull Trout, Brook Trout, and Bull Trout x Brook Trout hybrids.