Evaluation of Ovaprim and human chorionic gonadotropin doses on spawning induction and egg and larval quality of pinfish, Lagodon rhomboides

Abstract

The use of exogenous hormones to induce final oocyte maturation (FOM), ovulation, and spawning has become commonplace in the reproductive protocols for many species. Dose efficacy can be highly variable among species and factors such as temperature and stress may further obfuscate the hormone's perceived efficacy. The pinfish, Lagodon rhomboides, is a marine baitfish species with great potential for commercial development. This species readily undergoes vitellogenesis in captivity, however progression through FOM is unreliable. Therefore, the objectives of this investigation were to assess the effects of various doses of Ovaprim® (sGnRHa+domperidone) and human chorionic gonadotropin (HCG) on ovulation and spawning in pinfish.Two experiments were conducted to determine efficacious doses of Ovaprim and HCG in pinfish. Ovaprim dosages investigated were 0.25, 0.50, 1.00, and 2.00mL/kg, injected into the dorsal musculature of female pinfish. Male pinfish received one half the dosage (0.125, 0.25, 0.50, and 1.00mL/kg) administered to females to ensure spermiation. Experimental HCG doses of 500, 1000, 2000, and 4000IU/kg were administered to female pinfish with male pinfish once again receiving half the dosage (250, 500, 1000, and 2000IU/kg). Spawned eggs were collected over a 72hour period post injection and enumerated and assessed for fertilization, hatching percentage, and survival to first feeding. Additionally, eggs and larvae were photographed and a suite of morphological parameters was evaluated.Doses of 0.25 and 0.50mL/kg Ovaprim were efficient at induction of FOM and spawning in pinfish. Superior fecundity, fertilization and 3day post hatch (DPH) survival rates, as well as larger 3 DPH larvae support lower Ovaprim doses as the preferred choice for use with this species. Conversely, the 4000IU/kg HCG dose performed the best of all HCG doses evaluated eliciting the greatest spawning frequency from female pinfish.