Tag Archives: Trans-generational genetic mark and recapture (tGMR)

Abundance Estimates for Stillaguamish River Chinook Salmon Using Trans-generational Genetic Mark Recapture

The primary objective of this trans-generational genetic mark-recapture (tGMR) project is to: 1) estimate the abundance of Chinook salmon spawners and effective breeders in the Stillaguamish River above the smolt trap site using genetic abundance methods. The secondary objectives of this study are to: 2) estimate the natural spawning Chinook salmon abundance by origin (hatchery or natural), sex and age, and 3) estimate a redd expansion calibration factor from historic redd-based escapement estimates and possible future redd counts. The data collected for this project also provide a genetic baseline for these population estimates, a genetic (parentage-based) estimate of the proportion of hatchery-origin spawners, and an estimate of relative reproductive success of hatchery spawners, because carcasses are classified by origin. Genetic sampling will be conducted during the fall spawning period, and smolt trapping will be conducted during the following spring.



Genetic-Based Abundance Estimates for Snohomish River Chinook Salmon

This project, begun in 2012 by the Washington Department of Fish and Wildlife under the Sentinel Stocks Program to estimate the abundance of Chinook salmon spawners and effective breeders in the Snohomish River, continues today in partnership with the Tulalip Tribes of Washington using trans-generational genetic mark recapture (tGMR) and trans-generational rarefaction curve analysis (tRC). Additional objectives are to partition the genetic-based abundance estimate for natural spawning Chinook by origin, sex, and age, and assuming adequate data are acquired, and to develop a redd expansion calibration factor to adjust historical (or future) redd-based escapement estimates.
Funding is requested to collect and genotype subyearling offspring of the previous brood year, and to collect carcass samples from spawners in the fall. The Snohomish River basin is comprised of two Chinook salmon populations: the Skykomish River summer Chinook population (which includes Skykomish, mainstem Snohomish, and Pilchuck River) and the Snoqualmie River fall Chinook population. We expect to deliver tGMR and tRC abundance estimates for both populations for each brood year that is successfully sampled.