Grabowski, T. B., S. P. Young, L. A. Libungan, A. Steinarsson and G. Marteinsdóttir. 2009. Evidence of phentotypic plasticity and local adaption in metabolic rates between components of the Icelandic cod (Gadus morhua L.) stock. Environmental Biology of Fishes 86:361-370.
Phenotypic plasticity and local adaptations are important considerations in delineating population structure of marine fishes and critical to their conservation and management. We compared the weight-specific oxygen consumption rates (VO2/M) of juvenile cod from the northern and southern components of the Icelandic stock acclimated to 4.0°C, 8.5°C, and 12.6°C and their metabolic response to abrupt temperatures changes within this range. Southern individuals exhibited VO2/M up to 50% higher than their northern counterparts when tested at their acclimation temperature. However, northern fish generally experienced greater changes in VO2/M, three to six-fold increases, relative to that expected at acclimation when moved to higher temperatures. Southern cod showed a greater decrease in VO2/M when exposed to lower temperatures. Our results indicate physiological differences exist between the northern and southern components of the Icelandic cod stock and warrant considering them as two distinct populations.