Investigation of some hormones effecting osmoregulation of Van fish (Alburnus tarichi) reproductive migration

Lake Van is one of the largest soda lakes in the world. The extreme characteristics of the lake greatly limit the living life. Van fish (Alburnus tarichi) is the only vertebrate species adapted to in this environment the which is fatal to other acuatic animals. Van fish migrate to fresh water every year for breeding. The fish return to the lake environment, which they have completed their breeding. Fish are exposed to different aquatic areas during migration. Physiological regulation of fish is under the endocrine control system as well as multicellular organism. In this study, pH, temperature and ion levels (Na, K, Cl) of the water in the lake, downstream, river inlet and upstream regions that Van fish were exposed during the reproduction migration were determined. Cortisol, Free Triiodotronin (FT3), Free Thyroxine (FT4), Insulin-like Growth Hormone (IGF-I), Growth Hormone (GH), Prolactin Hormone (PRL) levels were also investigated. It was observed that the sampled ions decreased in freshwater localities compared to lake localities and serum ion levels were kept at a certain level. It was determined that the hormone levels differed in the upper regions of the river where the reproduction was completed from the lake environment where the reproduction started. As a result, it was determined that the measured hormones had direct and indirect effects on osmoregulation in Van fish as in other teleost species.