Thyroid hormones changes in reproduction season of brownbanded bamboo shark (Chiloscyllium punctatum) from the Persian Gulf

Brownbanded Bamboo sharks (Chiloscyllium punctatum) is one of the cartilaginous fish that lives in the Persian Gulf. OBJECTVES: The purpose of the present study is to study the effects of thyroid hormone on reproductive system of this specious. In this investigation, 36 individual of Brownbanded Bamboo sharks (Chiloscyllium punctatum) in both autumn (before reproduction) and spring (period of reproduction) seasons were caught from Dervish’s Creek located at the northern of Persian Gulf. After weighing, biometry, sex determination and the numbering of sharks, (the sex is determined through clasper which is observed in male and not in female), ELISA was used to measure serum thyroid hormone concentrations. The results showed that T3 and T4 hormones were increased dramatically in the reproductive season compared with the non-breeding season (p<0.05). On the other hand, by classifying the sharks into different groups, we found that the levels of thyroid hormone were higher in the blood of larger sharks compared with the smaller ones (p<0.05). It is probable that T4 hormone levels will increase dramatically for the development of eggs in the female shark.