EFFECTS OF SIZE ON OPTIMAL TEMPERATURE FOR GROWTH AND GROWTH EFFICIENCY OF IMMATURE ATLANTIC HALIBUT (HIPPOGLOSSUS-HIPPOGLOSSUS L.)

The aim of this study was to determine the optimal temperature for gro wth and growth efficiency for different size-classes of immature halib ut. In experiment A, lasting for 99 days, six groups of fish of initia l mean weight 8 g were reared at 7.3, 10.0, and 12.8 degrees C, two re plicates at each temperature. In experiment B, lasting for 216 days, s ix groups of fish of initial mean weight 140 g were oared at 5.0, 7.4, 9.0, 11.1, 13.0, and 14.9 degrees C. In experiment C, lasting for 189 days, six groups of fish of initial mean weight 2.9 kg were reared at 2.4, 4.6, 7.0, 9.8, 12.6, and 15.1 degrees C, The halibut were fed dr y feed in experiments A and B, and fish (capelin and herring) in exper iment C. In all three experiments growth rate and growth efficiency pe aked at intermediate temperatures. Optimal temperature for growth decr eased with increasing fish size, being approximately 14 degrees C for 10-60 g fish, 11.4 degrees C for 100-500 g fish and 9.7 degrees C for 3-5 kg fish. Optimal temperature for growth efficiency also decreased with increasing fish size, being approximately 14 degrees C for 10-60 g fish, 10.6 degrees C for 100-500 g fish and 5.5 degrees C for 3-5 kg fish. The dome-shaped relationships of growth rate and growth efficie ncy versus temperature became flatter with increased size of fish, sug gesting that thermal sensitivity close to the optimum decreases as fis h size increases.