RESPIRATION OF JUVENILE ARCTIC COD (BOREOGADUS-SAIDA) - EFFECTS OF ACCLIMATION, TEMPERATURE, AND FOOD-INTAKE

Oxygen consumption (VO2) of juvenile Arctic cod (Boreogadus saida) was investigated at low temperatures (six temperatures; range -0.5 to 2.7 degrees C). Small (mean wt. 6-8 g) and large (mean wt. 14 g) fish wer e acclimated, or adjusted to a constant temperature (0.4 degrees C), f or 5 months and then tested for metabolic cold adaptation (elevated me tabolic rates in polar fishes). Short-term (2 weeks) acclimated fish s howed elevated VO2 similar to previously established values for polar fishes, but there was: no such evidence after longterm acclimation. Lo ng-term acclimation caused VO2 values to drop significantly (from 86.0 to 46.5 mg O-2 . kg(-1). h(-1), at 0.4 degrees C), which showed that metabolic cold adaptation was a; phenomenon caused by insufficient acc limation time for fish in respiration experiments. We also measured th e effects of temperature and feeding on VO2. A temperature increase of 2.3 degrees C resulted in relatively large increases in VO2 for both long- and short-term acclimated fish (Q(10) = 6.7 and 7.1, respectivel y), which suggests that metabolic processes are strongly influenced by temperature when it is close to zero. Feeding individuals to satiatio n caused significant increases in VO2 above pre-fed values (34-60% wit hin 1-2 days after feeding). Respiration budgets of starved and fed Ar ctic cod at ambient temperatures in Resolute Bay, N.W.T., Canada, were used to model annual respiration costs and potential weight loss, Low respiration costs for Arctic cod at ambient temperatures result in hi gh growth efficiency during periods of feeding and low weight loss dur ing periods of starvation.