Hatching success, survival, growth and behavior were monitored in landlocked Atlantic salmon, Salmo salar, which were exposed as eyed embryos to a 1:1:1:1 suspension (by weight) of Aroclors 1016, 1221, 1254 and 1260. The embryos were immersed in nominal concentrations of 0, 0.0625, 0.625, 6.25 or 62.5 mg/l of the PCB mixture for 48 hours. The ontogeny of phototaxis in alevins, and the avoidance of predation by fry were assessed as neurobehavioral indicators of sublethal PCB toxicity. Average embryonic residues of 1.534, 0.857, 5.594, and 14.163 ug/g (wet weight) PCB were derived from the lowest to highest exposure concentrations, respectively. Control embryos were burdened with a background of 0.33 ug/g PCBs. PCB residues in whole alevins and emergent fry were reduced when compared to the embryonic burdens, because of dilution from growth; there was no appreciable elimination of total PCBs through yolk absorption. Differences in hatching success and survival through 6 months post hatching were not significant. Growth measurements (n = 5/treatment) of wet weight, total length, dorsal, pectoral and anal fin height were taken at two week intervals through yolk absorption (i.e., emergence); wet weight was the most sensitive growth parameter of those utilized in this study. Significant differences were observed between treatments in the wet weight of alevins at 50% hatch (r = (-0.97)) and at four weeks post hatch (r = -0.72). The inverse dose-response relationships observed at these time points, and at emergence (r = (-0.96)), were not detected at two weeks post hatch. On the final sample date, 176 days post PCB exposure, wet weight and length were significantly reduced (n ⩾134/treatment) in fed-fry exposed embryonically to the two highest PCB concentrations.

Results from one through four weeks after hatching indicate that PCBs may retard the development of negative phototactic behavior initially after hatching, thereby delaying the subsequent shift to phototropic behavior which occurs in-situ just prior to alevin emergence. Fry exposed to the highest embryonic PCB concentration were significantly less successful at avoiding predation upon a novel encounter with a smallmouth bass, Micropterus dolomieui.