Synchronous Hermaphroditism and Self-Fertilization in a Captive Shortnose Sturgeon

Abstract

The shortnose sturgeon Acipenser brevirostrum is a federally listed endangered fish species endemic to the East Coast of North America, where captive fish are cultured for recovery efforts. During routine evaluations of broodfish for spawning potential, a single hermaphroditic shortnose sturgeon was discovered. Motile sperm and approximately 7,600 eggs were manually stripped from the individual simultaneously. Eggs were fertilized with the fish's own sperm (self-fertilized) and with the sperm of two unrelated males (cross-fertilized). Both self- and cross-fertilization procedures were successful. Viable fry hatched from 9% of the eggs produced by self-fertilization and from 2% of those produced by cross-fertilization. Fry survival through 180 d posthatch was 1% in the self-fertilization treatment and 11% in the cross-fertilization treatment. Endoscopic evaluation of gonads confirmed the presence of ovotestes with discrete regions of active testicular and ovarian tissues. The present account provides empirical evidence including gross anatomical and histological photodocumentation that advances knowledge of this rare condition in a fish species threatened with extinction.