Benjamin Sandford, Jesse Lamb, Gordon Axel

NOAA Fisheries, 3305 E. Commerce St, Pasco, WA 99301

PIT-tagging is a tool to assess survival, movement, migration and other performance metrics for salmon, lamprey, and sturgeon and other fishes that has been used in the Columbia River Basin for over three decades by an increasingly diverse set of federal, state, tribal, and private organizations. Once PIT-tagged, fish have the potential to be detected while in their natal streams all the way to passage through the hydropower system (FCRPS). Detection in natal streams is currently feasible due to the increasing availability and performance of instream arrays.  These are placed in smaller streams and rivers spanning most or all of the wetted width, often resulting in moderate to high PIT-tag detection rates.  These rates vary depending on various factors such as tag detection range, flow depth, and fish behavior.  Instream array detections can help us more accurately assess survival and migration timing metrics to downstream locations.

NOAA Fisheries has been a key player in developing and implementing instream arrays since the installation of the array in Valley Creek, ID in 2002.  Wild Chinook salmon tagged in eight Salmon River Basin streams feeding into the lower Snake River have migrated past pertinent instream arrays and provided temporal survival and migration timing information to the hydro-system beginning at Lower Granite Dam.

The most recent addition that benefits our long-standing research monitoring wild Snake River Chinook salmon is the Marsh Creek array located 8 km above the Middle Fork of the Salmon River which began service in October 2019.  We captured, PIT-tagged, and released wild Chinook salmon parr in the summers of 2019 and 2021-2023 a few kilometers above this array.  These fish migrated downstream past the array over the following nine-ten months, and we examined detections at the array and at Lower Granite Dam.  Objectives evaluated (and major findings) for two years include:

 (1) Detection rate at the array (range 86-95%);

 (2) Survival from release to the array (57-68%);

 (3) Passage distributions at the Marsh Creek array (many in the first couple weeks, most of the rest before December, but some trickled out over the winter through May), and at Lower Granite Dam (late April through early June);

 (4) Overall survival from the array to Lower Granite Dam (31-32%); and

 (5) “Seasonal” survival from the array to Lower Granite Dam as determined by passage date at the Marsh Creek array (28-29% in fall, 34-55% in winter, and 45-78% in spring). 

We will present multiple methods to estimate these metrics for consistency and examination of assumptions.