This project proposes to continue a study to investigate the utility of yearling Chinook enhancement as a conservation tool for West Coast Vancouver Island (WCVI) Chinook salmon. An experimental group of Chinook from Robertson Creek will be reared for ~18 months and released at the yearling stage to compare marine survival, maturation rate, marine distribution and exploitation rate to the traditional subyearling Chinook release that is used at DFO hatcheries. This project will fund the rearing and coded wire tagging of 100K Chinook juveniles for brood years 2017 and 2018, which will be compared to the traditional subyearling release strategy that is currently employed on WCVI. As the Stamp River is currently the WCVI PST exploitation rate indicator, terminal assessment capability is very high. This strategy has been proposed as a tool for extreme conservation situations where maximizing the total return from a limited number of available eggs is desired. It has also been hypothesized that by utilizing multiple release strategies, that brood year failures due to poor ocean entry conditions in any one year can be avoided. There is little recent empirical information on this strategy and its potential utility or risk as a tool for Chinook conservation. This project will address that gap and allow for improved decision making to fully understand the risks and benefits of this strategy as a component of a comprehensive conservation plan for Chinook populations of concern.
