Presentation Abstract
Salmon hatcheries face the challenging task of developing release strategies that attempt to maximize survival and minimize risk to wild populations. Release strategies refer to the size at release, timing of release, nature of release (i.e. forced or volitional), number of releases, release location, and the use of acclimation facilities prior to release. We led an extensive review of hatchery release strategies and how they can be used as a management tool to influence production outcomes (i.e. survival, catch, and return ages). The review consisted of three components: 1) a systematic review of the literature from BC and the western United States, 2) a review of release experiments conducted on coded wire tagged Chinook and Coho salmon at BC hatcheries over the past 20 years, and 3) a Bayesian hierarchical model of the effects of release strategies on survival using over 40 years of coded wire tagged Chinook and Coho data from 21 Chinook and 16 Coho hatcheries in BC. Overall, we found that most hatcheries could improve survival rates by releasing fish larger than the historical average size-at-release. In addition, Chinook survivals improve when released 1-4 weeks earlier, while Coho survivals improve when released 1-4.5 weeks later than the historical average release timing at most hatcheries. The size and timing of releases for maximizing survival rates varies across hatcheries, as does the degree to which altering release strategies can lead to notable improvements. We also found that random year effects can account for large proportions of the variability in hatchery survival rates and may limit the ability to measure the impacts of release strategies in short-term experiments. This research can equip hatchery managers with the best available information and facilitate informed, science-based decision making moving forward.
Session Title
Hatchery, Habitat, & Survival
Conference Track
SSE4: Fish Science and Policy
Conference Name
Salish Sea Ecosystem Conference (2022 : Online)
Document Type
Event
SSEC Identifier
SSE-traditionals-466
Start Date
27-4-2022 1:30 PM
End Date
27-4-2022 3:00 PM
Rights
Copying of this document in whole or in part is allowable only for scholarly purposes. It is understood, however, that any copying or publication of this document for commercial purposes, or for financial gain, shall not be allowed without the author's written permission.
Type
Text
Language
English
Hatchery release strategy effects on production outcomes for Chinook and Coho
Salmon hatcheries face the challenging task of developing release strategies that attempt to maximize survival and minimize risk to wild populations. Release strategies refer to the size at release, timing of release, nature of release (i.e. forced or volitional), number of releases, release location, and the use of acclimation facilities prior to release. We led an extensive review of hatchery release strategies and how they can be used as a management tool to influence production outcomes (i.e. survival, catch, and return ages). The review consisted of three components: 1) a systematic review of the literature from BC and the western United States, 2) a review of release experiments conducted on coded wire tagged Chinook and Coho salmon at BC hatcheries over the past 20 years, and 3) a Bayesian hierarchical model of the effects of release strategies on survival using over 40 years of coded wire tagged Chinook and Coho data from 21 Chinook and 16 Coho hatcheries in BC. Overall, we found that most hatcheries could improve survival rates by releasing fish larger than the historical average size-at-release. In addition, Chinook survivals improve when released 1-4 weeks earlier, while Coho survivals improve when released 1-4.5 weeks later than the historical average release timing at most hatcheries. The size and timing of releases for maximizing survival rates varies across hatcheries, as does the degree to which altering release strategies can lead to notable improvements. We also found that random year effects can account for large proportions of the variability in hatchery survival rates and may limit the ability to measure the impacts of release strategies in short-term experiments. This research can equip hatchery managers with the best available information and facilitate informed, science-based decision making moving forward.
