Spawning induction of the mangrove snapper, Lutjanus griseus Linnaeus (Pisces: Lutjanidae ), maturated in captivity

Abstract

The mangrove snapper Lutjanus griseus is one ftsh species that has been sucessfully cultured at the experimental farm. This species has a commercial importance and it is priced at $ 6.0/kg. A total of 5,200 juveniles, with a weight from 34.1±8.9 to 53.3±17.7 g, were caught and reared in ponds. After seven months in captivity, with average weights from 159.7±33.7 to 301.3±48.9g anda survival rate of 86% some individuais were detected to be sexually mature. In this research, two groups of mangrove snapper were selected with averages weight of 330 and 1,150 g. Females were treated with HCG (1.0; 3.4; 4.4; 5.6 and 6.3 Ul/g). The spawnings were detected at 51 and 31 hours after the injection, respectively. The eggs were spherical and pelagic with average diameters of 740.2±19.1 and 760.1±59.6 mm anda oi! drop of 139.3
to 133.0 mm diameter. In the first experiment, 36% of fertility was observed, however ali the eggs died at neurula stage. In the second experiment 174,950 eggs (411.6 eggs/g of jish) were spawned, with a fertilization of 85.85%. The hatchout rate was 68.04%. The survival rate in the first 24 h was 79.16%. A total of 80,896 larvae have been cultured in tanks