M.T. Ridha, E.M. Cruz, A.A. Al-Ameeri, A.A. Al-Ahmed-1998
Aquaculture Research, 29: 403-410
Abstract:
An experiment was conducted to compare the seed production of tilapia, Oreochromis spilurus (Gunther), under ambient water temperature and photoperiod, and under controlled water temperature (29.0 +/- 2.0 C), and photoperiods of 13 and 14 h/day. Male and female breeders with average weights of 155.4 and 78.7 g, respectively, were stocked in nine 1.04 x 1.04 x 0.40 m (L x W x H) fibreglass tanks. Each tank was stocked with two males and six females. Seed collection was carried out biweekly for 300 days. The results showed that the seed/kg female/day, seed/m2/day, total seed production per tank and spawning rates of females were highest during the 14h/day photoperiod (112.4, 77.4, 24 724 and 42.1%, respectively), followed by ambient spawning conditions (104.0, 57.9, 18 356 and 36.6%, respectively), and lowest during the 13h/day photoperiod (49.5, 36.5, 12 021 and 25.7%, respectively). Under ambient spawning conditions, peak spawning occurred in May. Monthly seed production was affected by changes in temperature and light duration. In both controlled photoperiods, the peak of seed production was observed during the first month after stocking. In all treatments, spawning declined gradually after the peak, which can be attributed to exhaustion of the breeders. The findings of this study indicate that seed production of O. spilurus in Kuwait can be extended beyond the restrict spawning season of 6-7 months by maintaining water temperature at 29.0 +/- 2.0 C and a photoperiod at 14h/day.
(Mariculture and Fisheries Department, Food Resources Division, Kuwait Institute for Scientific Research, P.O.Box 1638, 22017 Salmiya, Kuwait)