Influence of temperature on gonadal maturation of the male common snook Centropomus undecimalis

Abstract

 The objective of the present study was to verify the influence of the temperature on gonadal maturation of the common snook, Centropomus undecimalis, in laboratory. Natural photoperiod was simulated using fluorescent lamps (1,000 lux). Water temperature was controlled with heaters. The fish (n=54), with 2,348 ± 488 g in weight and 642 ± 40 mm in length, were distributed in six experimental units. These consisted of 8,000-L tanks containing a biological filter and sea water renewal. Two treatments with three replicates were applied: T1 = temperature varying from 19.9°C at the beginning to 26.0°C in March (natural variation) and T2 = constant temperature of 26.0°C from October to May. Maturation was followed taking bimonthly samples from September to May (2006/2007). There were no significant differences (p >0.05) between treatments in weight, length, condition factor, specific growth rate, volume of semen and on the number of spermiating fish. However, optimum period of sperm production was the March month. The results had not allowed to define optimum thermal regime between the two tested. It was observed that a precocious increment for the temperature of 26.0°C, still in the spring, did not favor the gonadal maturation. Therefore, new experiments are necessary to determine the action of the temperature and other ambiental parameters, in way to obtain a better control of the gonadal maturation of the common snook in captivity.