Lemhi Effectivenes Monitoring, P2

This contract is for the second phase of the Lemhi River Intensively Monitored Watershed (IMW), which began with PCSRF project #002 11 SA.

WS#1 Abundance, distribution, movement, and migration of juvenile spring/summer Chinook salmon & steelhead was monitored using remote-site juvenile capture/tagging/recapture surveys, rotary screw traps, and in-stream PIT tag detection systems (IPTDS). Juvenile distribution & movement was correlated to habitat pairing habitat metrics with juvenile abundance estimates.

Juvenile abundance in the mainstem & tributaries were estimated with capture/mark/recapture surveys. Estimates for sampled reaches were generated using a Darroch/Plante maximum likelihood estimator & extrapolated to unsampled areas. Abundance estimates are reported by stratum & location.

Sex & age-structured natural-origin Chinook and steelhead escapement to the Lemhi R. was estimated by PIT tagging a fraction of natural-origin individuals as they ascend the adult ladder at Lower Granite Dam (LGR). Detection of adults as they pass PIT tag arrays and are recovered during carcass surveys is used with a branch-occupancy model to estimate total escapement. Total escapement is then parsed by sex and age by analysis of tissue & scale samples collected during tagging at LGR. Spatial distribution of spawning is assessed from redd count data. From this work about 26% of Chinook spawning occurred in Hayden Cr.; the remaining occurred in the upper-mainstem Lemhi R. PIT tag detections were insufficient to assess spatial distribution of steelhead spawning.

Habitat condition was monitored at 4 restoration projects, pre and post-implementation, these sites included the Amonson Reach/Lemhi River, Lee & Little Springs creeks and Eagle Valley Ranch.

Time-series water temperature data from IPTDS located on Hawley, Eighteenmile, lower Hawley, Big Timber, Big Springs, Lee, Big Eightmile, Wimpey, Carmen, Hayden, Bear Valley & Agency creeks were used to calibrate a continuous temperature model (McNyset et al. 2015); temperature criteria from Carter (2005) was used to evaluate the temporal fraction of key life history stages for which water temperatures were below minimum, within optimum ranges, or above maximum ranges established for Chinook. These data suggested winter temperatures may be too low, and temperatures are higher than optimum for spawning, incubation, and summer parr in the Lemhi River.

Worksite 2: The East Fork Salmon River in-stream PIT tag detection system (IPTDS) was installed in November 2016 approximately one kilometer upstream from the confluence with the Salmon River. The IPTDS will provide estimates of adult spring/summer Chinook salmon and steelhead escapement for the East Fork Salmon River.

Worksite 3: The North Fork Salmon River in-stream in-stream PIT tag detection system (IPTDS) was installed in November 2015 about one kilometer upstream from the confluence with the Salmon River. The IPTDS will provide estimates of adult spring/summer Chinook salmon and steelhead escapement for the North Fork Salmon River.

Within the Lemhi River watershed, the primary benefit of the program will be a quantitative evaluation of whether habitat restoration actions achieved improvements in freshwater productivity for steelhead and spring/summer Chinook salmon, respectively, as identified in the 2008 Biological Opinion on the Federal Columbia River Power System (NOAA 2008). Furthermore, effectiveness monitoring results generated from these studies will support an adaptive management approach within the Lemhi and will inform future restorative actions. We also intend to capitalize on the intensive sampling conducted in the Lemhi River to develop fish/habitat relationships, associated tools, and response designs that can be applied to other watersheds with planned restoration actions.