FIELD STUDIES OF REPRODUCTIVE SUCCESS AND BIOINDICATORS OF MATERNAL CONTAMINANT EXPOSURE IN ENGLISH SOLE (PAROPHRYS-VETULUS)

Our studies have shown that early stages of the reproductive process in female English sole (Parophrys vetulus) are disrupted by contaminant exposure. To determine the potential for contaminants to affect later stages of the reproductive cycle, we examined the effects of maternal contaminant exposure on egg and larval viability in this species, in a field study conducted on running ripe fish collected for two consecutive years from spawning grounds. Maternal contaminant exposure was assessed by measuring levels of polychlorinated biphenyls (PCBs) in ovarian and hepatic tissue, biliary levels of fluorescent aromatic compounds (FACs), and hepatic aryl hydrocarbon hydroxylase (AHH) activities. Additionally, the presence of significant liver disease or ovarian atresia was documented, and levels of plasma estradiol were measured. Stepwise multiple regression of the data showed that contaminant exposure was only a minor factor in determining both egg and larval viability. Hepatic AHH activity showed a slight negative correlation with fertilization success, explaining only 4% of the variability. Increased levels of PCBs in ovaries of spawning female English sole were not associated with reduced reproductive success. However, because the range of contaminant exposure in the spawning fish did not encompass the high levels seen in non-spawning fish captured from contaminated areas, it can be hypothesized that female English sole exposed to substantial levels of contaminants might be at least partially excluded from the spawning population.