CONTAMINATION OF FOOD BY CRUDE-OIL AFFECTS FOOD SELECTION AND GROWTH-PERFORMANCE, BUT NOT APPETITE, IN AN ARCTIC FISH, THE POLAR COD (BOREOGADUS-SAIDA)

The polar cod (Boreogadus saida) is recognized as a key species in Arc tic marine food webs and it may, therefore, be important for the trans fer of xenobiotics from lower trophic levels to its main predators, bi rds and sea mammals. The present work examines the effects of foods co ntaminated with 200 or 400 ppm crude oil on food selection patterns an d appetite-growth relationships in polar cod using X-radiography. It i s shown that sexually mature polar cod consumed mixtures of uncontamin ated and oil-contaminated foods, and did not show a reduced overall ap petite as compared with fish provided with uncontaminated food only. F ood selection was, however, influenced by both sex and individual appe tite. Male fish selected uncontaminated food when appetite was low, wh ereas females ingested contaminated and uncontaminated foods equally, irrespective of appetite level. The ingestion of oil-contaminated food led to a significant depression in growth performance in both male an d female fish. Food contaminated with oil at a concentration of 500 pp m was completely rejected by both sexes.