Variation in migration pattern, broodstock origin, and family productivity of coho salmon hatchery populations in British Columbia, Canada, derived from parentage‐based tagging

Abstract

In salmonid parentage‐based tagging (PBT) applications, entire hatchery broodstocks are genotyped, and subsequently, progeny can be nonlethally sampled and assigned back to their parents using parentage analysis, thus identifying their hatchery of origin and brood year (i.e., age). Inter‐ and intrapopulation variability in migration patterns, life history traits, and fishery contributions can be determined from PBT analysis of samples derived from both fisheries and escapements (portion of a salmon population that does not get caught in fisheries and returns to its natal river to spawn). In the current study of southern British Columbia coho salmon (Oncorhynchus kisutch) populations, PBT analysis provided novel information on intrapopulation heterogeneity among males in the total number of progeny identified in fisheries and escapements, the proportion of progeny sampled from fisheries versus escapement, the proportion of two‐year‐old progeny (jacks) produced, and the within‐season return time of progeny. Fishery recoveries of coho salmon revealed heterogeneity in migration patterns among and within populations, with recoveries from north and central coast fisheries distinguishing “northern migrating” from “resident” populations. In northern migrating populations, the mean distance between fishery captures of sibs (brothers and sisters) was significantly less than the mean distance between nonsibs, indicating the possible presence of intrapopulation genetic heterogeneity for migration pattern. Variation among populations in productivity and within populations in fish catchability indicated that population selection and broodstock management can be implemented to optimize harvest benefits from hatcheries. Application of PBT provided valuable information for assessment and management of hatchery‐origin coho salmon in British Columbia.

Insights on the concept of indicator populations derived from parentage‐based tagging in a large‐scale coho salmon application in British Columbia, Canada

“…As outlined by Beacham et al. (2019b), water temperatures at the Puntledge River hatchery become too high during the summer for juvenile rearing, so approximately 85% of the production from the 2014 and 2015 broodstocks was released as fry and was not adipose‐fin‐clipped. Fry survival would be lower than for smolts released from other EVCI hatcheries, potentially accounting for the lower productivity of the population.…”

“…Beacham et al. (2019b) previously outlined jack PBT assignments for the 2016 hatchery broodstocks, and jack and adult PBT assignments for the 2017 hatchery broodstock and escapement samples, with PBT assignments made to parents in the 2014 and 2015 hatchery broodstocks. The current study incorporates this previous information and adds to it the 2018 fishery PBT assignments and the 2018 hatchery broodstock and escapement PBT assignments, with PBT assignments made to parents in the 2014, 2015, or 2016 hatchery broodstocks.…”

“…As noted by Beacham et al. (2019b), the typical hatchery spawning design was to cross a single male with a single female, but in practice some males produced offspring from more than one female, presumably as a result of carryover of viable sperm in a fertilization bucket even with intervening rinsing and drying between fertilizations. Population distributions were compared statistically via Fisher's exact test.…”

“…(2019a) provided evidence that PBT‐GSI‐based assessment and management of hatchery origin and wild coho salmon were a practical approach, as demonstrated by a large‐scale application to fisheries management and assessment in BC. Population‐ and family‐specific distributions among fisheries, origins, and productivity of hatchery broodstocks and associated stray rates among populations were also evaluated via PBT (Beacham et al., 2019b). As well as providing improved estimates of stock composition from mixed‐stock fisheries, PBT allows evaluation of family‐specific productivity and exploitation, evaluation of productivity in specific components (differentiated by life‐history type, spawn times, or rearing environment) of a hatchery broodstock, assessment of hatchery–wild interactions in salmonids (Araki, Berejikian, Ford, & Blouin, 2008, McClure et al, 2008, Jones & Wang, 2010), and the genetic basis for salmon migration and marine residency.…”

Large-scale parentage-based tagging and genetic stock identification applied in assessing mixed-stock fisheries and hatchery brood stocks for coho salmon in British Columbia, Canada

“…Beacham et al (2019a) provided evidence that GSI-PBT-based assessment and management of hatcheryorigin and wild coho salmon was a practical approach, as demonstrated by a large-scale application to fisheries management and assessment in British Columbia (BC). In addition, population-and family-specific distributions among fisheries, origins, and productivity of hatchery brood stocks and associated stray rates among populations were evaluated via PBT (Beacham et al 2019b). These approaches showed large potential, providing an impetus to continue genotyping brood stocks and to increase the number of participating hatcheries.…”