Geographic variation in growth and food conversion efficiency of juvenile Atlantic halibut related to latitude

Higher growth capacity and food conversion efficiency was observed in popul ations of juvenile halibut from high Hippoglossus hippoglossus compared low er latitudes. In addition, temperature adaptation shown by the lower temper ature optimum for growth in the Norwegian population (mean +/- S.E. 12.9 +/ - 0.1 degrees C) compared with the Icelandic and Canadian populations (14.2 +/- 0.2 and 13.9 +/- 0.3 degrees C respectively), seems to occur. Overall the data support the hypothesis of countergradient variation in growth. The se results have implications firstly for selection focusing on growth perfo rmance in halibut culture; and secondly, for safe prediction of growth, sin ce if countergradient variation in growth performance occurs one cannot ass ume automatically that a species will respond to the same set of physiologi cal parameters in the same way throughout its range. (C) 2000 The Fisheries Society of the British Isles.