Influence of sex on growth of juvenile Greenland halibut (Reinhardtius hippoglossoides) in the Estuary and Gulf of St. Lawrence

Abstract

Understanding growth in early life stages is fundamental for commercial fisheries management, but there are few studies dealing with growth trajectory divergences occurring during the juvenile stage. We monitored the growth of individually tagged two-year-old juvenile Greenland halibut captured in the wild and maintained at 4 °C for 17 months. The animals were still at the juvenile stage (no ovary or testis development through the maturation stage) at the end of the experiment. In the absence of energetic allocation to gonad development, female juveniles were larger than male juveniles, with a greater gain in mass and length. Female juveniles rapidly reached a higher Fulton’s condition index compared to male juveniles. However, no difference in glycogen, lipid, or protein liver composition or muscle energy storage was found between the sexes. Plasma cortisol was higher in male juveniles, suggesting males were more sensitive to captivity than females. Pre-maturation divergences in juvenile growth could result in or accentuate the size-related sexual dimorphism observed in nature among adults.