Comparative analyses of contaminant levels in bottom feeding and predatory fish using the National Contaminant Biomonitoring Program data

Using a Two Sample-t test, no significant differences could be found in the mean residue levels between bottom feeders and predators for 16 of the 18 pesticides and PCB analysed. Significant differences in tissue residue levels between bottom feeders and predators were only found for trans-chlordane and Aroclor 1260. For trans-chlordane, the mean residue level in bottom feeders was greater than in predators while the reverse was true for Aroclor 1260. Results of the Two Sample-t tests for metals showed significant differences in tissue levels for mercury, cadmium and zinc out of the 7 metals surveyed.