The impact of petroleum derivatives derived from fuel drums dumped into McMurdo Sound during the period before environmental management practices were regarded was examined on fish in Winterquarters Bay (McMurdo Sound). Experimental fish were captured from a relatively pristine site (Backdoor Bay, Cape Royds) and transported to Winterquarter Bay (heavily polluted) and Cape Armitage (minimally ... impacted) where they were held in cages. The fish were sampled from both sites after periods of 2 and 4 weeks and examined for physiological condition. Naturally resident fish were also collected from Backdoor Bay and Winterquarters Bay to provide a second, independent set of data. The physical condition of each fish was noted on gross examination and morphometric data was gathered to provide further information on health status. Internal organs (gills and liver) were then sampled for histopathological and biochemical analysis (measurement of cytochrome P450 content and activity). Bile was also removed from the gall bladder for subsequent analysis of petroleum derivative content by fluorimetry. These methods test for correlations between the amount and activity of cytochrome P450 in exposed fish and the quantity of contaminating petroleum contaminants.