Study on propagation and breeding of Hamoun fish (shizothoraxzarudnyi) to one gram weight in earthen pond

Abstract

Hamoun fish, Schizothorax zarudnyi, is an indigenous species of the eastern waters of Iran, which is exclusively found in this region. However recently drought occurrence in the Chahnimeh reservoirs (a semi natural water body) making them vulnerable to extinction. As an appropriate action to address this problem and according to the 3 side contract between Italian Government – UNDP - Islamic republic of Iran Government and the Italian government financial support to reduce poverty in the Province of Sistan-Baluchestan through the reinforcement and dissemination of aquaculture activities the project was developed at the Hamoun Research Unit by the Chahbahar Fisheries Research Center to record the breeding normative of 1 g weight larvae for restocking and other researching purposes. 331 broodstocks of the indigenous species Shizothorax zarudnyi weighing 800-2450 g were collected from the Chahnimeh reservoirs in early autumn, 2006. From 5/3/2007 ( the project is supported and communicated on 2010) , Ovulation was stimulated with three stimulators; pituitary extract (3-6 mg kg-1 body weight), GnRH-A (20-30 mg kg-1 body weight) and anti dopamine (10-15 mg kg-1 body weight) that was given in 2-3 doses to breeders. Of 169 injected breeders , some were injected On mid March of 2007 (12-13 ºC water tempreture) responded to the injection 25% ,while the rest were injected On April of 2008 (14-16 ºC water tempreture) responded to the injection 65%. In the present project of 167 breeders 82 were female and 87 male. Totally 30 female breeders released their eggs in different stages. 20 female breeders released their eggs completely, 3 breeders released half of their eggs and 7 released 1/3 of their eggs. The male breeders just injected in the final dose of hormontrapy and all were ready for releasing sperms however the ovulation in female breeders occurs between 353-428 h ºC and after the final dose of injection. Ripe eggs were stripped from the females and fertilization was done by the dry method. Fertilized eggs were transferred to veis incubators and troughs. Incubation period for eggs differs and larvae hatch out after about 910 days at an average water temperature of 12.5 °C. Maintained at 13-14 °C, complete absorption of yolk sac in Shizothorax zarudnyi larvae occurred after 5-8 days. Larvae were fed with a mixture of powdered milk and egg yolk in this stage followed by decapsulated Artemia cysts and nauplii of Artemia and then on formulated starter diets used for carps . Because the ponds were not ready, larvae were maintained in troughs for about ten days before they were transferred to two 1200 m2 earthen ponds where they reached a body weight of about 1 g. They were then handed over to the Iranian Fisheries department in the region. Larvae were fed with the starter feed SFCO in the earthen ponds. About 350 thousand larvae were stocked in two earthen ponds. Based on the results of present study and other studies we may conclude that artificial breeding in Schizothorax can be successfully achieved at 14-16 ºC in flow through systems using hormone therapy (combination of GnRha and anti dopamine) and larvae could be easily cultured in earthen ponds. However this species exhibits lower growth rates as compared to carps its high expenses could have an important role in economical feasible.