Plasma vitellogenin levels in male common carp Cyprinus carpio and crucian carp Carassius cuvieri of Lake Kasumigaura

In order to investigate the possible influence of estrogenic environmental endocrine disruptors on the reproductive activity of fish in Lake Kasumigaura, plasma levels of vitellogenin (VTG), a biomarker of estrogen exposure, were measured in wild and cultured male common carp Cyprinus carpio and wild crucian carp Carassius cuvieri . Testicular histology and plasma steroid hormone levels were also examined. Fish were collected from June 1998 to August 1999. Plasma VTG levels in most fish examined were below a detection limit (40 ng/mL) throughout the sampling period, and a small amount of VTG (43.5 ng/mL–1680 ng/mL) compared to that in females was detected in some fish. Active spermatogenesis in the testis and increased levels of plasma sex steroids were observed in most of the fish examined. Thus, no marked influence of estrogenic chemicals was detected in the reproductive activity of male common carp and crucian carp in Lake Kasumigaura collected from the sampling sites in the present investigation.