INDUCTION OF GONADAL MATURITY IN THE MUTTON SNAPPER LUTJANUS ANALIS (PISCES: LUTJANIDAE) BY THE APPLICATION OF AN ARTIFICIAL PHOTOTERMAL CONDITIONING CYCLE

Abstract

An experimental group (N=7) of three females and four males of mutton snapper Lutjanus analis captured in the wild, whose gonadal development entered in a state of latency because of its confinement in the lab, was maintained under an artificial photothermal cycle of 10 months between October 2001 and July 2002 in order to unblock and estimulate again their sexual maturation. Another group of equal number of fish was used as a control, being maintained during the same time without manipulation of temperature and photoperiod parameters. After eight months the three females of the experimental group showed positive gonadal development signs, their oocyte mean diameters (Ø) reaching 122 ± 76; 86 ± 40; and 122 ± 87 μm respectively. During the tenth month one female reached the state III of gonadal development (Ø = 327 ± 67 μm) and was induced to final maturation and spawning by a single injection of 1,000 IU/kg of HCG. The spawning occurred 64 h after the injection with approximately 25,000 eggs (Ø = 713 ± 56 μm) which reached the early gastrula stage 4:35 h after fertilization. The artificial photothermal cycle applied showed to be effective to unblock and stimulate gonadal development of the captive fish, preliminary result that must be confirmed by further research and which could constitute an important step in the development of a technology for the artificial reproduction of the mutton snapper.