Reproductive performance in induced and spontaneous spawning of the mangrove red snapper, Lutjanus argentimaculatus: a potential candidate species for sustainable aquaculture

Abstract

A reliable breeding technique was developed for the mangrove red snapper, <i>Lutjanus argentimaculatus</i> (Forsskal 1775), to help sustain the aquaculture of this immensely popular species in Southeast Asia. Using standardized indices of female maturity (based on mean oocyte diameter of ≥0.40&nbsp;mm), time of injection (1000–1130) and sex ratio (one female to two males), a single injection of 100&nbsp;μg&nbsp;kg⁻¹ luteinizing hormone-releasing hormone analogue (LHRHa) (<i>n</i>=16 fish), but not 50&nbsp;μg&nbsp;kg⁻¹ (<i>n</i>=five fish), successfully induced egg (62.5% success rate) and larval (43.8%) production. Human chorionic gonadotropin (hCG) at 500&nbsp;IU&nbsp;kg⁻¹ (<i>n</i>=five fish) also failed to induce spawning, but doses of 1000 (<i>n</i>=22 fish) and 1500&nbsp;IU&nbsp;kg⁻¹ (<i>n</i>=15 fish) gave spawning (77.3% and 80.0% respectively) and hatching success rates (72.7% and 60.0% respectively) that were not significantly different from those of 100&nbsp;μg&nbsp;kg⁻¹ LHRHa. No spawning was observed in saline-injected controls (<i>n</i>=seven fish). While mean spawning latency, egg diameter, egg production per spawn, percent egg viability, hatching rate, percent of normal larvae and cumulative survival of eggs to normal larvae did not differ significantly among the effective hormones and doses, 1000&nbsp;IU&nbsp;kg⁻¹ hCG had a higher percentage (76.5%) of total spawns with egg production per spawn in excess of one million than those of 1500&nbsp;IU&nbsp;kg⁻¹ hCG (50.0%) and 100&nbsp;μg&nbsp;kg⁻¹ LHRHa (40.0%). Mangrove red snapper spontaneously spawned from March–April to November–December with a peak of egg collection and spawning in May–June. Egg collection per spawn ranged from 0.05 to 6.35 million. Spontaneous spawning of mangrove red snapper exhibited lunar periodicity with spawns mostly occurring 3 days before or after the last quarter and new moon phases and occurred consistently between 02:00 and 04:00 hours. High fecundity and good egg quality, coupled with the ability to respond to induce spawning or natural spawning in captivity, provide a sound basis for improving the sustainability of red snapper aquaculture in Southeast Asia.