No butts about it: using urogenital disparity in a deep-water snapper, Etelis carbunculus (Lutjanidae), for field-based sexual identification.

In this study, the authors describe a process that consistently identified sex based on differences in the length and characteristics of the urogenital papilla septum of Etelis carbunculus, a deep-water snapper (Lutjanidae, Etelinae). These characteristics, regardless of fish size, were found to be accurate for 96% of 157 specimens evaluated. The application of this external sex determination technique expedites the collection of sex-specific data and may perform well for other morphologically similar lutjanid snappers. The non-invasive method also minimizes damage to the fish, thereby allowing either its return to the ocean or landing as a valuable whole fish.