The Integrated Status and Effectiveness Monitoring Program (ISEMP) is an ongoing collaborative effort to design, test, implement and evaluate Status and Trends Monitoring for salmon and steelhead populations in the interior Columbia River Basin. The use of Passive Integrated Transponders, or PIT tags, is one tool that the Salmon River Basin ISEMP project is using to answer scientific uncertainties regarding adult and juvenile steelhead Oncorhynchus mykiss and Chinook salmon O. tshawytscha. Specifically, PIT tags can be used as a tool by which growth, survival, and migratory patterns of juvenile steelhead and Chinook can be examined and quantified. The ISEMP Salmon study design proposed the use of in-stream extended length PIT tag arrays coupled with representative adult PIT tagging at Lower Granite Dam (LGD) as a means to provide reliable and consistent adult escapement estimates into tributary streams. The study design relies on PIT tag arrays to provide “recapture” data for wild/natural adult salmon and steelhead PIT tagged at LGD. Thus, interrogation of adults passing in-stream PIT tag arrays can be used to decompose the adult run-at-large passing LGD into precise and reliable estimates of adult escapement for stream-type Chinook salmon, and steelhead at the subpopulation, population, and major population group (MPG)/distinct population segment (DPS) spatial scales.. The ISEMP Salmon project currently operates and maintains 31 in-stream arrays within the Clearwater River (4), Grande Ronde River (2), Imnaha River (5), South Fork Salmon River (6), Middle Fork Salmon River (2), Lemhi River (8), and upper Salmon River (4) basins.
For its part, the Nez Perce Tribe is responsible for the operation, maintenance, QA/QC of detection data, and data analysis from in-stream PIT tag arrays and for a rotary screw trap operated in the lower Secesh River, a tributary to the South Fork Salmon River. In 2012 alone, the ISMEP Salmon in-stream arrays recorded over 1 million PIT tag detections. Unique PIT tag detections at ISEMP Salmon in-stream PIT tag arrays accounted for 31.4% of the 2012 spring/summer Chinook and 22.8% of the 2011-12 steelhead wild/natural adults PIT tagged at LGD. In-stream PIT tag detections are further used to assess and quantify adult escapement into tributary streams, describe adult migration and arrival timing, monitor adult straying and dip-in behavior, estimate adult residency time, estimate kelting rate, monitor juvenile abundance and survival, and describe juvenile migration timing and patterns.