The environmental tolerances and metabolic physiology of sablefish (Anoplopoma fimbria)

Given the potential impacts of global warming, such as increases in temperature and the frequency/severity of hypoxia in marine ecosystems, it is important to study the impacts of these environmental challenges on sea-cage reared aquaculture species. This study focuses on the sablefish (Anoplopoma funbria), an emerging aquaculture species that has a unique ecology in the wild. For instance, adults inhabit oxygen minimum zones and cool waters at depths up to 1500 m. Using Atlantic salmon (Salmo salar) (similar to 1132 g adults) as a comparative species, we used intermittent-flow respirometry to characterize the tolerance and metabolic response of sablefish (similar to 10 g juveniles and similar to 675 g adults) to acute increases in temperature (2 degrees Ch(-1)) and decreases in oxygen level (similar to 10% air saturation h(-1)). Adult sablefish were much more hypoxia tolerant than adult salmon [O-2 level at loss of equilibrium similar to 5.4% vs. similar to 24.2% air saturation, respectively]. In addition, sablefish could withstand upper temperatures only slightly lower than salmon [critical thermal maximum (CTmax) similar to 24.9 degrees C vs. similar to 26.2 degrees C, respectively]. Sablefish juveniles were both less hypoxia and thermally tolerant than adults [critical O-2 tension similar to 18.9% vs.similar to 15.8% air saturation; CTmax similar to 22.7 vs. similar to 24.9 degrees C, respectively]. Interestingly, many of these differences in environmental tolerance could not be explained by differences in metabolic parameters (aerobic scope or routine metabolic rate). Our findings show that sablefish are tolerant of high temperatures, and very tolerant of hypoxia, traits that are advantageous for an aquaculture species in the era of climate change.