Changes in electrolytes and urea of blood according to the reproduction season and body size in the Brown banded Bamboo shark (Chiloscyllium punctatum) from Persian Gulf

Abstract

Cartilaginous fishes were used urea to regulate osmolarity of internal fluids. Despite studies on the regulation of blood osmolytes values, the effect of body size and reproduction on concentration of these materials seems necessary. In this investigation, 36 individual of Brown banded 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 catching sharks, the blood samples were taken from fish and then weighing, biometry and the numbering of sharks. The electrolyte analyzers and auto analyzer was used to measurement respectively of serum electrolytes and urea concentrations. The results showed that there was no significant difference in the concentration of blood osmolytes between males and females (P>0/05), but there was a significant difference between the sharks caught in autumn with sharks caught in spring (P<0/05). On the other hand, with classifying the sharks into different groups becames that the levels of osmolytes were higher in the blood of smaller sharks than larger one (P<0/05). So that, Striking result of this study, the relative reduction in blood electrolytes and urea concentrations are associated with increased body size.