Growth and Survival of Juvenile June Suckers in Enclosures in Utah Lake: Feasibility of Modified Cage Culture for an Endangered Species

An objective of the recovery program for the federally endangered June sucker Chasmistes liorus is to produce large numbers of artificially propagated individuals to augment the wild population and offset recruitment deficits. We tested the feasibility of modified cage culture in Utah Lake, Utah, as a cost-effective addition to the current hatchery program. Specifically, we examined the survival and growth of age-0 June suckers from July to September at two densities (62 and 187 fish/m3) in two cage types (fixed and floating; n = 12 cages total) in a complete factorial design and compared the cost of production with hatchery costs of production. June suckers were not given supplemental feed during the study but instead preyed on zooplankton that drifted into the cages. Mean survival of June suckers was 45.5% and was not significantly different between cage types or density. Cage design significantly affected growth of June suckers, with fish growing larger in floating cages (mean standard length [SL] = 56.7 mm) than in fixed cages (mean SL = 49.6 mm). Density significantly affected growth in fixed cages (mean SL = 52.5 and 46.6 mm in low- and high-density cages, respectively) but did not significantly affect growth in floating cages. Comparison of costs of production between cage and hatchery production indicates that cage culture would be a cost-effective addition to the current June sucker augmentation program.