Notes on hatchery spawning methods for bigmouth sleeper Gobiomorus dormitor

Abstract

The bigmouth sleeper Gobiomorus dormitor, a popular sport fish within its native range, offers a management alternative to exotic species currently managed for recreational fishing. Hatchery production and stocking are needed to create reservoir sport fisheries because this species usually requires access to marine environments for recruitment. Bigmouth sleepers have not been spawned previously in a hatchery, and hence we used natural, artificial and semi-natural spawning techniques. No egg deposition or propagation resulted from natural pond spawning. Artificial spawning techniques using Ovaprim® and Chorulon® injections followed by hand stripping were more successful. Semi-natural (hormone injections plus volitional spawning) spawning trials using Ovaprim® and Chorulon® displayed the greatest potential, and three consecutive evening injections (1.0 mL kg⁻¹) of Chorulon® appeared most conducive. High-fecundity spawning was achieved by injecting bigmouth sleeper pairs and allowing volitional spawning in aquaria with spawning cavities. Initial success in 2007-2008 was isolated to wild-caught fish, but captive broodstock were spawned using these techniques in 2009. Eggs hatched in <20 h at 23-24 °C. The resulting larvae, 1.0-1.5 mm in length, displayed large yolk sacs, unpigmented eyes and no apparent mouth. These hatchery propagation efforts suggest that hormone-induced semi-natural spawning has the greatest potential for bigmouth sleeper propagation.