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

Abstract

AbstractBurbot 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.