بررسي امكان جايگزيني تانن به جاي خاك رس در فرايند تكثير مصنوعي تاس ماهي ايراني ( acipenser persicus borodin , 1897)

The examination of Tanoan replacement to Clay in artificial propagation process of (Acipenser persicus)

Acipenser persicus is endomic and more abundance sturgeon fish in Caspian Sea. Artificial propagation of Acipenser persicus has significantly emerged in recent years due to the prolonged maturation age and destroied breeding grounds .One of the artificial propagation stage of Acipenser persicus is eggs removed adhesiveness by using clay . utilize some water to make 10 percent clay suspension , then washed the fertilized eggs for 45 minutes to removed eggs adhesiveness . this process takes a lot of time in propagation . Tanoan can be a material as a suitable replacement for clay. In this study 2 brooder females of Acipenser persicus used in propagation season 2008. After breeding and artificial propagation, each eggs of brooder divided in to 8 portion. A treatment(0.625grTanoan per 1.25 liter water ) and an control (10 percent clay suspension ) and each one washed with 4 replicate . According to the results, washing time for Tanoan is 1 minute and 30 seconds but for clay is 45 minute. Thus, for tanoan and clay the fertilization rate in washed eggs in Gastrula stage are 94.36 and 91.28 percent respectively. Fungal infected percent are 1.81 and 5.04 respectively, hatching rate 92.82 and 89.49 , larvae survival rates to yolk sac resumption are 93.49 and 89.94 respectively. The replacement of Tanoan would save time and economical evaluation in the process and also a few number of fertilize eggs re exposed to the possible threat of being damaged. It will also increase the larvae survival rates in propagation.