Growth in adult gilthead sea bream (Sparus aurata L) as a result of interference in sexual maturation by different photoperiod regimes

Abstract

Gilthead sea bream (Sparus aurata L) pass through the period of sexual maturation while being intensively reared for commercial purposes. This process affects growth and food conversion efficiency. In an attempt to reduce this problem several lighting regimes have been utilized which impede gonad development by increasing the length of the day. A four hour increase in natural day length three months before reaching sexual maturation in fish of 390 g, improves growth in comparison to the control by about 15% (means SD of 606.2 +/- 10.6 and 526.5 +/- 12.7 g, respectively) towards the end of the natural reproductive season. However, these differences are subsequently compensated since the sexual maturation process is only delayed (rather than being permanently halted). The manipulated groups reached maturity and then stopped growing between three and four months after the control groups. For this reason, it would appear advantageous to manipulate sexual maturation through photoperiod alteration in those groups which go to market either during or towards the end of the reproductive season since greater fish weights will be achieved in addition to an improved food efficiency.