Applications of hepatic mixed function oxidase enzyme activities to northern freshwater fish: 1. Burbot, Lota lota

Burbot Lota lota from the Mackenzie river drainage in northwestern Canada were collected following complaints that the quality of these fish had deteriorated in parallel with expansion of petroleum production at Norman Wells. Petroleum hydrocarbons enter the river there from natural seepage and from refinery operations. In fish, the hepatic cytochrome P450 system is inducible by experimental treatment with petroleum and PCBs; this system should show some response if exposures to these materials were meaningful biologically. Here we report liver microsomal cytochrome P450-related catalytic activities ethoxyresorufin-O-deethylase and aryl hydrocarbon hydroxylase, and levels of cytochrome P450. From the geographic pattern of catalytic activities, there was no suggestion of a linkage with the site of petroleum inputs. PCB residues showed a south-to-north concentration gradient for the less volatile congener classes, but there was no parallel gradient in enzymatic activities.