Reduced growth of Atlantic cod in non‐lethal hypoxic conditions

Abstract

Growth in length and mass, improvements in condition, as well as final condition of c. 700 g Atlantic cod Gadus morhua were significantly less at 45% and 56% O 2 saturation than at 65%, 75%, 84% and 93% O 2 saturation. Hypoxia decreased food consumption. In turn, food consumption explained 97% of the variation in growth. Conversion efficiency varied slightly, but significantly, with level of dissolved O 2 , except that the group reared at 93% O 2 had a lower than expected conversion efficiency. Slow growth in low O 2 was not due to increased activity, because activity decreased in hypoxia. In the Gulf of St Lawrence, waters deeper than 200 m usually are <65% saturated in O 2 , and thus should impact negatively on cod growth.