Hormonal stimulation of reproduction and development of intensive juveniles production techniques in the red claw crayfish Cherax quadricarinatus in recirculation systems

This study was carried out in four different experiments in order to develop the red claw crayfish (Cherax quadricarinatus) cultivation in Turkey. In the 1st Experiment; in an attempt to control reproduction, two different hormone injections (Methyl Farnesoate (MF) and Serotonin) and unilateral eyestalk ablation were tested on the reproductive performance of this crayfish. In the 2nd Experiment; feeding live Artemia or fresh minced feeds were tested to decrease mortality in the new offspring. In the 3rd Experiment; production efficiency at different stocking densities (20, 40, 60 and 80 pcs/m2) were investigated, while in the 4th Experiment; a three-stacked tank design operating with a recirculation system (RAS) was studied to produce a large amount of offspring from the unit production area. In the 1st Experiment; the highest GSI values were obtained in MF (1.88), eyestalk ablation (1.62) and serotonin groups, but these values were not different from the control groups (1.28-1.47) (P>0.05). The ovary weight per gram of female was found to be highest in the MF, serotonin and eyestalk ablation groups (18.29, 15.71 and 15.44 g, respectively) (P>0.05). Estradiol, progesterone, total testosterone, total protein, triglyceride and lactate as well as ALP, AST and ALT levels were similar in all groups (P>0.05). In the 2nd Experiment; the highest survival rate was sustained by live Artemia (83.81%) and artificial feed (80%) and the lowest by minced squid (58.10%) (P<0.05), indicating that the crayfish juveniles can directly be fed successfully with only artificial feed. In the 3rd Experiment; the survival rate for all stocking groups were high ranging from 72.08% to 81.67%, and the increase in stocking density decreased the survival rate, weight and specific growth rates (SBO). In the 4th Experiment; a three-stacked tank system operating in RAS was demonstrated to produce offspring with a survival rate of over 90% even under super intensive culture conditions. Thus, it was shown that, in cold winter months, using the vertical volume of the greenhouse in RAS can yield a higher number of offspring at more economical costs. In the last two trials, total protein, triglyceride, lactate, ALP, AST and ALT values were not affected by stocking densities (P>0.05).