Spawning induction of fat snook, Centropomus parallelus, throuth injection and LHRHa implant

Abstract

The efficiency of the use of luteinizing hormone-releasing hormone analogue (LHRHa) was tested for the spawning induction of the fat snook, Centropomus parallelus. From January to May 1999, two experiments were carried out. Forty-two females, 525-1,580 g, and 84 males, 324-1,041 g, were submitted to three treatments: injection of 50 µg/kg of LHRHa diluted in saline solution, implantation of a cholesterol pellet with the same dose of the hormone and control, with implantation of a cholesterol pellet without LHRHa. Fish normally spawned once, 35 - 42 h after the hormone was taken. Two females, with cholesterol pellets implanted, spawned twice in a 24 h interval. Considering treatments, there were no significant differences (P>0.05) between the production of eggs and fertilized eggs, and the rates of fertilization and hatching. In the first experiment, the pellet treatment resulted in a mean egg production of 42.27 x 10⁴/kg, a mean fertilization rate of 75.8% and hatching rate of 89.5%. The injection treatment resulted in a mean egg production of 87.11 x 10⁴/kg in a single spawning, with fertilization and hatching rates of 99.0% (spawning of one single female). In the second experiment, the pellet treatment resulted in an average egg production of 45.12 x 10⁴/kg, and average fertilization and hatching rates of 93.8% and 88.0%, respectively. With the injection treatment, average egg production was 41.01 x 10⁴/kg and average fertilization and hatching rates were 94.5% and 80.5% respectively. These results suggest that the methodologies used in this work are promising to the induced reproduction of fat snook.