Juvenile Greenland halibut (Reinhardtius hippoglossoides) growth in the context of rising temperature in the Estuary and Gulf of St. Lawrence

Abstract

In a context of climate change, understanding the influence of temperature on fish species growth is important for the management of fisheries. The effect of increasing temperature on the growth of juvenile Greenland halibut (Reinhardtius hippoglossoides), a cold-water species, circum-continental in the Arctic, was investigated on juveniles that had been captured in the wild and kept in captivity. Mortality rate increased with higher temperature, from 4.5 % at 4.0 °C to 15.2 % at 7.5 °C. Relative growth (normalized in degree-days) was lower at 7.5 °C than at the two other temperatures tested. Food conversion efficiency, muscle energy content, and the Fulton condition index were not influenced by temperature, but food intake significantly increased over time at 5.5 °C. No clear difference in growth trajectories between sexes was highlighted. Overall, the results suggest that optimal temperature conditions were exceeded at 7.5 °C and that any further increase in temperature would significantly decrease survival and impair juvenile growth. With the current deep-water warming trends in the Estuary and Gulf of St. Lawrence, recruitment and commercial fishing of Greenland halibut may be impaired in the near future.