ASPECTS OF REPRODUCTION AND LARVAL BIOLOGY OF ARCTIC COD (BOREOGADUS-SAIDA)

Arctic cod (Boreogadus saida) were captured from Resolute Bay, Northwe st Territories, shipped to Vancouver and reared in holding tanks for u p to three years. Spawning and development of larvae were monitored in two separate years. Fish that were in the laboratory for less than on e year spawned during the normal spawning period for wild fish, Januar y to February. The timing of spawning was altered by water temperature and light regime. Elevated water temperature caused spawning to occur earlier, and increased mortality and rate of deformity in larvae. The absence of ''light'' and ''dark'' seasons may have caused spawning to deviate from the predicted time in successive years. Larvae hatched a t 87-91 degrees C days. The newly hatched planktonic larvae were 5-6 m m long (total length), non-pigmented, and had poor swimming ability, l ikely because of the large yolk sac (1.5 mm in length). Even though sw imming ability remained poor for the entire rearing time (up to 100 da ys), it improved as the yolk dissipated. Yolk nutrition lasted 20 to 4 0 days after hatching. Healthy larvae remained within the top 15 cm of the water column, and fed on brine shrimp and barnacle nauplii, and o yster trochophores. Growth rate under laboratory conditions was simila r to those for fish sampled from the field. Fish that were not near th e surface did not grow.