Effect of water temperature on off-season reproduction of pacific white shrimp (Litopenaeus vannamei)

This project covers investigations on how to control off-season maturation and spawning of an American shrimp species Pasific white shrimp (Litopenaeus vannamei), of which post-larvae were brought into our country for the first time by Ç.U., Faculty of Fisheries from Thailand in 2008, by using various maturation techniques. For the experiment, the broodstock were separated into three groups (Group 1: Control, Group 2: Ablated, and Group 3: Temperature fluctuated) in April 2009. Each group was stocked into a 2-m diameter round tank at density of 9.55 shrimps/m2 (2:1, female/male). Eyestalk-ablated group developed their gonads faster than the other groups but first spawnings were achived on 25-28th days of the experiment in all the groups. Throughout the experiment, the highest spawning rate (55%) and fecundity (79.778 eggs) were obtained from the eyestalk-ablated groups (P<0.05). Cyclic temperature fluctuation (Group 3) stimulated ovarium maturation in 39% of the females with a fecundity of 28.500 eggs per female (P<0.05). Mean egg fertility rates ranged from 86.25% to 88.37%, and hatching rates from 8.53% to 31%. The results of this study has demonstrated that, under Mediterranean climatic conditions, the broodstock of this non-indigenous shrimp species can be readily matured and spawned out of season in recirculating systems.