GASTRIC EVACUATION RATES AND DAILY RATIONS OF ARCTIC COD (BOREOGADUS-SAIDA) AT LOW-TEMPERATURES

Gastric evacuation rates were determined for different sizes of Arctic cod (Boreogadus saida) at subzero temperatures (-1.4 and -0.5 degrees C). These temperatures represent ambient conditions for Arctic cod in the Canadian high Arctic. Evacuation half-times, the time required fo r half of the content of the stomach to be evacuated, were longer (36- 70 h; mean = 51h) than those reported in studies carried out on other fish species. Gastric evacuation rates at low temperatures were equal to, or below, those predicted by extrapolation from experiments conduc ted at higher temperatures. There were no significant differences in e vacuation rates among fish size-groups or diets, but evacuation rates were slower for fish that had been starved prior to experiments. Estim ated daily rations for Arctic cod in Resolute Bay, N.W.T., were 0.51% body weight for small fish (4.5 g) and 1.13% body weight for large fis h (51 g). Slow stomach evacuation rates at low temperatures may limit daily food intake when food is seasonally abundant. This may contribut e to slow growth rates and limited maximum size of Arctic cod in Canad ian high Arctic waters.