Growth, metabolism, and dissolved oxygen tolerance of juvenile burbot

Abstract

The burbot, Lota lota, is being explored as a novel aquaculture species in North America due to its palatability and potential to be grown in areas that currently support rainbow trout, Oncorhynchus mykiss culture. Dissolved oxygen (DO) concentration is a primary limiting factor in fish survival and growth, with tolerance varying among species. We exposed juvenile burbot (19.5 ± 2.2 g) to five dissolved oxygen concentrations (5.0, 5.8, 6.6, 7.4, and 8.3 (control) mg·L −1) for 9 weeks at 15 °C. Size variability was high in all treatments, and food consumption, and growth rates did not differ among DO levels, although fish at 8.3 mg·L−1 grew ca. 29% larger than those at 5.0 mg·L−1. We also measured short-term hypoxia tolerance and resting routine oxygen consumption rates (MO2) of burbot that had been chronically acclimated to the same DO concentrations. Burbot acclimated to 8.3 mg·L−1 lost equilibrium (LOEcrit) at a significantly higher concentration (1.85 ± 0.33 mg·L −1) than that of the 7.4 and 6.6 mg·L −1 acclimated fish (1.50 ± 0.37 and 1.49 ± 0.27; respectively), while all other groups were intermediate (1.67 ± 0.28). The MO2s were not statistically distinguishable among acclimation groups (p-value = 0.25), but MO2 trended lower with decreasing DO concentrations. In summary, juvenile burbot are tolerant to DO concentrations down to 5.0 mg·L −1. We recommend rearing burbot at DO concentrations >7.0 mg·L −1 to optimize growth, especially with the presence of multiple stressors.