A Meta-Analysis of Factors Potentially Influencing Contribution of Stocked Largemouth Bass to a Year-Class

We reviewed 135 stocking events from 21 published studies to identify factors that influence enhancement of largemouth bass populations with hatchery fish.  Factors examined included system type and size, how hatchery fish were fed, size at stocking, stocking density, and marking and sampling methods.  We used logistic regression to determine which factors resulted in a high contribution of hatchery fish to the year-class in the fall and spring following stocking, and whether these factors contributed to investigators deeming their stocking event successful. System size ranged from 1-8484 ha.  Stocking size ranged from 23-315 mm. Stocking density ranged from 1-645 fish/ha.  Contribution of hatchery fish to a year-class ranged from 0-100% and from 0-90% in the fall and spring, respectively. Median stocking contributions were 15% and 14% for the fall and spring, respectively.  Logistic regression indicated that stocking fish raised on minnows was more likely to result in high fall contributions to the year-class, but this relationship disappeared by spring.  Stocking larger fish was more likely to result in high fall contributions to the year-class, but again, this relationship disappeared by spring. How fish were marked and sampled were not related to year-class contribution.  Stocking size and density were both related to whether an investigator felt the stocking event was successful.  Events with high stocking density and relatively large stocking size were more likely to be deemed unsuccessful.  Furthermore, mean stocking contributions did not differ significantly between events deemed successful and unsuccessful.  Careful consideration of hatchery rearing methods and stocking program goals may aid in realizing stocking program success.