Maturation Spawning and Larviculture of Atlantic Croaker (Micropogonias undulatus) at Low Salinity

Atlantic Croaker is a popular baitfish among anglers targeting a variety of gamefish in the Gulf of Mexico. Aquaculture of this species could help meet the demand for Croaker, especially during winter when wild-caught Croaker are unavailable. Currently, Croaker aquaculture involves broodstock maturation, spawning, and larval culture at high salinity. This protocol prevents the direct use of coastal water for culture along the Mississippi Gulf coast where salinity is low. This study examined the feasibility of performing hatchery production of Atlantic Croaker at low salinity. Culture of Croaker broodstock at 10, 20, and 30 psu during the maturation period was compatible with the completion of gametogenesis in both sexes. Results of hormonal induction of spawning revealed that sperm production, ovulation rates, fecundity, and fertility of spawns were reduced at 10 psu and maximized at 20 psu. Neutral buoyancy of Croaker eggs was reached at 25 psu in all groups indicating that embryos should be incubated at this salinity or higher. In a second experiment, larvae cultured at 30 psu (typical of wild spawning conditions) were transferred at 1, 5, 12, 18, and 25 days post hatch (dph) to 2, 10, 20, and 30 psu. Larval survival duration post-transfer increased with age, in particular following development of the gills, and was highest when larvae were transferred to 10 psu, suggesting that stress and maintenance energy needs are reduced in iso-osmotic conditions. Practical culture at low salinity for early stage Atlantic Croaker may be possible, but also limited by the buoyancy of larvae