Genetic diversity and phenotypic variation within hatchery‐produced oyster cohorts predict size and success in the field

Abstract

The rapid growth of the aquaculture industry to meet global seafood demand offers both risks and opportunities for resource management and conservation. In particular, hatcheries hold promise for stock enhancement and restoration, yet cultivation practices may lead to enhanced variation between populations at the expense of variation within populations, with uncertain implications for performance and resilience. To date, few studies have assessed how production techniques impact genetic diversity and population structure, as well as resultant trait variation in and performance of cultivated offspring. We collaborated with a commercial hatchery to produce multiple cohorts of the eastern oyster (Crassostrea virginica) from field‐collected broodstock using standard practices. We recorded key characteristics of the broodstock (male : female ratio, effective population size), quantified the genetic diversity of the resulting cohorts, and tested their trait variation and performance across multiple field sites and experimental conditions. Oyster cohorts produced under the same conditions in a single hatchery varied almost twofold in genetic diversity. In addition, cohort genetic diversity was a significant positive predictor of oyster performance traits, including initial size and survival in the field. Oyster cohorts produced in the hatchery had lower within‐cohort genetic variation and higher among‐cohort genetic structure than adults surveyed from the same source sites. These findings are consistent with “sweepstakes reproduction” in oysters, even when manually spawned. A readily measured characteristic of broodstock, the ratio of males to females, was positively correlated with within‐cohort genetic diversity of the resulting offspring. Thus, this metric may offer a tractable way both to meet short‐term production goals for seafood demand and to ensure the capacity of hatchery‐produced stock to achieve conservation objectives, such as the recovery of self‐sustaining wild populations.

Genome‐wide analysis of natural and restored eastern oyster populations reveals local adaptation and positive impacts of planting frequency and broodstock number

“…However, Hughes et al (2019) did not focus on restoration specifically and the experiments conducted were on a much smaller scale.…”

Reproductive phenology of the eastern oyster,Crassostrea virginica(Gmelin, 1791), along a temperate estuarine salinity gradient

“…Selective breeding for commercially valuable traits can cause reduced genetic diversity and potentially reduced lifetime fitness in a natural environment, making aquaculture lines often the least desirable option for restoring oyster populations (Baggett et al 2014). Enhancing or restoring a population with stocks that do not possess adequate genetic variation, or that have maladaptive variation, could be detrimental to overall population fitness and diversity (Camara and Vadopalas 2009;Morvezen et al 2016;Hornick and Plough 2019;Hughes et al 2019;Hornick and Plough 2022).…”

Individual and population‐level variation in susceptibility to temperature in early life history stages of giant kelp

“…Individuals with different genotypes in a population may fill different niches and increase ecosystem function. Just as species diversity increases ecosystem function (Hooper et al, 2005), an increase in genetic diversity in a population can increase seagrass resistance to disturbance and herbivory (Hughes & Stachowicz, 2004, 2009), oyster settlement and survival (Hanley et al, 2016; Hughes et al, 2019), and litter decomposition and nutrient levels under cottonwood trees (Schweitzer et al, 2005). In fact, intraspecific variability can be as or more consequential for determining ecological outcomes as variation among species (Des Roches et al, 2018).…”