Seasonal reproductive health of flounder Platichthys flesus exposed to sewage effluent

Indicators of environmental oestrogen exposure in male and female wild flounder Platichthys flesus were followed over the annual reproductive cycle. Fish were obtained from the Tyne estuary, UK, which receives effluent from a large sewage treatment works and several other anthrophogenic sources and the Solway Firth, UK, which receives only low levels of sewage effluent. Vitellogenin (vtg), a female-specific protein, was present in the plasma of up to 94 % of males from the Tyne and was accompanied by inhibited spermatogenesis and the incidence of pathological testicular abnormalities. The vtg levels in males are independent of the seasonal cycle. Female flounders from the Tyne exhibited increased vtg levels and a higher proportion of degenerating oocytes than Solway Firth females. This study provides limited evidence that wild populations of flounders showing oestrogenic responses are also suffering reproductive disturbances but the degree of alteration varies during the seasonal reproductive cycle.