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    Effect of Orally-Administered 17?-Methyltestosterone at Different Doses on the Sex Reversal of the Nile Tilapia (Oreochromis niloticus, Linneaus 1758)
    (Medwell Online, 2011) Celik, Ihsan; Guner, Yusuf; Celik, Pinar
    In order to obtain all male population, the Nile tilapia (Oreochromis niloticus) larvae which just finished the yolk sac were fed with feed containing 17 alpha-Methyltestosterone at five different doses (0, 20, 30, 40, 50 and 60 mgMT kg(-1) feed) for 28 days. As a result of the experiment repeated twice, it was found out that the sex reversal rates among the groups were at the levels of 57.1, 69.8, 69.4, 70.9, 86.1 and 93.7%, respectively. Furthermore, it was observed that the highest sex reversal rate occurred in the group to which 60 mgMT kg(-1) feed dose was applied.
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    Öğe
    Spawning and Larval Rearing in Hybrid Striped Bass (Morone chrysops ? X Morone saxatilis ?) in Turkey
    (Foundation Environmental Protection & Research-Fepr, 2016) Guner, Yusuf; Kizak, Volkan; Altunok, Muhammet; Celik, Ihsan
    This study is the first spawning and larval rearing of the F-1 hybrid striped bass (Morone chrysops female X M. saxatilis male) grown in culture conditions in Turkey. The F-1 Hybrid striped bass was fed with commercial pellet feed in floating net cages. They reached the sexual maturity at two years old. Female brood fish were given 30 mu g/kg of LHRH-a (Lutenizing hormone releasing hormone analogue) and male fish given 10 mu g/kg; of CHP(Dried carp pituitary), 4 mg/kg was used for the female and half that amount for the male for induced breeding. The fish injected LHRHa were successfully induced to both strip spawning and tank spawning by a single hormone injection. However, fish injected CPH and saline, untreated control did not spawn. Latency period was found to be 20.41 +/- 0.91 hour. In term of fertilization rate, larval deformity rate no significant difference was found between tank spawning and strip spawning (p>0.05). Fertilization rates ranged from 56.3% to 85.4% and hatch rates were between 0.99% and 46.88%, whereas the level of larval deformities ranged between 81.25% and 100%. Hatched larvae were placed into 400-liter rectangular tanks with water discharge of 4 liter/minute at a stocking density of 30 larvae/liter. After larvae hatching, they were given artemia nauplii for 5-19 days. Trout granule feed (300-500 micron) also started to be given in addition to artemia nauplii afterwards. Granule feed was started eating completely 24 th days. The larvae obtained from a single hatch in the production season reached 2.87 cm length in 32 days with 2.7% survival rate. Of this study was terminated due to white spot disease (Ichtyophthirius multifilis) arising from sudden change in water temperature. The F-2 progenies were not deemed to be available for aquaculture due to poor fertilization, poor hatching, low survival rate and high deformity rate. For the progenies of the hybrid striped bass that grow in natural water, it was suggested that their ecology in waters in Turkey be first studied and brought into aquaculture afterwards.