The stillaguamish tribe has conducted spawning ground surveys on the north fork of the stillaguamish river since 2001 with the objective of producing escapement estimates based on redd count expansion…

The stillaguamish tribe has conducted spawning ground surveys on the north fork of the stillaguamish river since 2001 with the objective of producing escapement estimates based on redd count expansion estimates and to recover coded-wire tags (cwts) and scales from chinook spawner carcasses on the spawning grounds. Tribal staff will read cwts and scales to determine hatchery of origin and age structure to provide a stock specific assessment of stillaguamish chinook. In 2008, the tribe incorporated tissue sample collection from spawner carcasses to establish a genetic baseline for a tran-generational mark-recapture (tgmr) project in collaboration with washington department of fish and wildlife. In tgmr, genotyped spawner carcasses are marks, genotyped out-migrating juveniles are captures and juveniles that assign back to a spawner parent are RE-captures. Tribal staff will determine a preliminary chinook escapement using redd data, adjusted by a linear regression calibration factor estimated from a direct comparison of tgmr and redd census abundance estimates. These data collection efforts and results will produce annual return estimates of total population size, hatchery/natural origin ratio, SEX ratio, and age class data. This proposal is requesting funding to support stillaguamish staff time and project needs to conduct stillaguamish river spawning ground surveys and collect spawner carcass genetic samples. Project objectives include: 1) coded-wire tag (CWT) recovery: collect scales from chinook carcasses in the north fork stillaguamish (RM 0 to RM 30) to determine age structure and recover cwts detected on the spawning grounds to evaluate stock composition. 2) spawning assessment: conduct a complete redd census in the north fork stillaguamish (RM 0 to RM 30) to further improve escapement estimates and gather information on spatial diversity of spawning ground habitat. 3) genetic stock identification: sample tissue of chinook carcasses for genetic analysis of stock identification (stillaguamish fall or summer population assignment) and tgmr abundance estimates to be compared with redd based estimates. We propose to meet the bilateral data standards for estimating the number of natural origin spawners including: 1) individual estimates of spawning escapement will have on average an estimated coefficient of variation (CV) of 15% or less; and 2) these specific estimates shall be consistent because the methods used to produce them are asymptotically unbiased. The tgmr project has received six years of funding from the sentinel stocks committee of the pacific salmon commission and four years of funding from the southern fund. Each year the project tasks were completed on schedule and within budget.