The effect of different initial size distributions on the growth of Atlantic halibut

Growth rate of individually tagged medium-sized (249 +/- 6.9 g) juvenile halibut was 18% lower when medium sized fish were reared alone (treatment Mm) as compared with rearing with either large/dominant (382 +/- 12.1 g) (Ml) or small/subordinate (158 +/- 3.1 g) (Ms) conspecifics. The coefficient of variation of weight of medium-sized fish increased with weight in both the Mm and the Ml group whereas it was stable in the Ms group. Size rank correlation between initial and final weight was highest in the Mm group and lowest in Ms. A negative rank correlation was found also between initial weight and overall growth rate for the Ms treatment groups but not the other groups. It is hypothesized that interactions between similar-sized individuals in the Mm treatment group had an inhibiting effect on growth as social hierarchies were being resolved. (C) 2000 The Fisheries Society of the British Isles.