Intersexes in Mississippi River shovelnose sturgeon sampled below Saint Louis, Missouri, USA

The Missouri Department of Conservation detected high organochlorine levels in tissues of fish from the Mississippi River south of Saint Louis. Chlord ane, which is both a carcinogen and an endocrine disrupter, reached 2960 mu g/kg in fillets of shovelnose sturgeon, Scaphirhynchus platyorynchus, and 1 926 mug/kg in their roe, wet weight basis. Polychlorinated biphenyls (PCBs) and p,p'-dichlorodiphenyldichloroethylene (DDE) in roe have reached 5810 a nd 780 mug/kg, respectively. The purpose of this study was to determine if endocrine disrupters and carcinogens are a potential cause of the significa ntly diminished reproduction capacity and population declines in the endang ered pallid sturgeon, Scaphirhynchus albus. Twenty-four surrogate shovelnos e sturgeons were sampled north of Saint Louis where contaminant levels were lower compared with 17 sampled south of Saint Louis where contaminant leve ls were high. Liver and gonad tissues were formalin-fixed, histologically p rocessed and examined. Neoplasms were not found. The principal finding was that the testes of two of the seven downstream male fish contained ovigerou s lamellae, in addition to mature sperm. Since sturgeons are gonochoristic and intersexes are rare and unusual, the occurrence of intersex in 29% of t he male Mississippi River shovelnose sturgeon examined from a population co ntaminated with chlordane and other chemicals raise concern for human healt h, species biodiversity and preservation of waterway quality. These finding s, however, need to be corroborated by expanded studies with a higher sampl e size. Published by Elsevier Science Ltd. All rights reserved.