Hydrogen Peroxide Treatments Administered to Hatchery-Reared Burbot: Assessing Treatment Regimes from Embryonic Development through Juvenile Rearing

Abstract

Burbot Lota lota is an emerging aquaculture species, in which fungal infestations during early life stage development are common. In this study, the tolerance of Burbot to external hydrogen peroxide (H₂O₂) treatment regimes was examined during four early life stages to determine species and life stage-specific sensitivity. Yolk-sac larvae tolerated three 1-h treatments up to 250 μL/L H₂O₂ without significant reduction in survival. Preflexion larvae tolerated only 100 μL/L H₂O₂ before survival was affected. In both cases, decreased survival was only observed after administration of three consecutive treatments. Flexion larvae tolerated up to 250 μL/L H₂O₂, but by the juvenile stage sensitivity again increased to 100 μL/L H₂O₂ before survival was affected. In these latter stages, decreased survival was observed immediately following the first H₂O₂ treatment, suggesting a mechanism for toxicity that is different than that in previous life stages. As has previously been shown, H₂O₂ can be effective for controlling aquatic bacteria and fungus at or below 250 μL/L, and our results indicate that H₂O₂ concentrations currently used during Burbot egg incubation may be extended into the larval rearing stage for effective fungal control without negatively affecting survival of either eggs or newly hatched larvae. Additionally, treatment regimes may be continued through juvenile development for the purpose of controlling external pathogens in the hatchery production of Burbot.

Received June 17, 2012; accepted September 1, 2012

ACKNOWLEDGMENTS

Funding for this research was provided by the Kootenai Tribe of Idaho and the Bonneville Power Administration (contracts 30729, 37267; project 198806400). We thank the British Columbia Ministry of Environment and Kootenai Valley Resource Initiative for their ongoing cooperation, as well as Josh Egan and Ryan Johnson for their help during this study. We also thank Neil Ashton for his involvement and supervision for applying this research to a production scale.