Validity of an external sex determination method in Atlantic Sturgeon (Acipenser oxyrinchus oxyrinchus)

The validity of the shape of the urogenital opening was tested as a predicable means to determine the sex of Atlantic sturgeon captured in the Saco River estuary, Maine. Evaluation of 121 individuals ranging in size from 107 to 182 cm fork length were compared to non-lethal radioimmunoassay determined sex data previously examined for these individuals within this estuary. The results suggested that using the shape of the urogenital opening is not a reliable means to determine sex as only 51% of Atlantic sturgeon were correctly identified as female. Additionally, there was no significant difference in correctness relative to 10 cm fork length size classes or sampling month.