LONG-TERM EFFECT OF DOPAMINE INJECTION ON OVARY MATURATION AND SOMATIC GROWTH OF Cherax quadricarinatus FEMALES (DECAPODA: PARASTACIDAE)

TROPEA, C. Y LOPEZ GRECO, L.S.

Congreso; WORLD AQUACULTURE SOCIETY MEETING 2011; 2011

Cherax quadricarinatus is a freshwater crayfish native of Australia and Papua New Guinea, which is cultured with commercial purposes. As in this species males grow faster and reach a larger size than females, one of the culture strategies are aimed at the increase of female somatic growth, in order to obtain greater meat yields. A possible way to achieve this purpose could be the inhibition of vitellogenesis, a process that competes from an energetic point of view with somatic growth. In this sense, dopamine was demonstrated to inhibit vitellogenin synthesis in the freshwater prawn Macrobrachium rosenbergii and to reduce the gonadosomatic index (GSI) in C. quadricarinatus females weighing 4 g. The objective of the present study was to evaluate the effect of dopamine injection over a long period (90 days) in females initiating ovary maturation (initial weight: 9.65±0.10 g). Females were randomly assigned to one of the following treatments: dopamine injection three times a week (DOPA group); physiological solution injection (group C). The animals were weighted twice a month, and at the end of the experiment they were sacrificed, measured and dissected. The ovaries were weighed and processed for histological analysis. The degree of ovary maturation tended to differ between treatments, with the majority of DOPA females presenting yellowish ovaries; mature olive green ovaries were seen only in the C group (Fig. 1; Table 1). Accordingly, the GSI was significantly lower (p<0.05) for the DOPA group. On the other hand, no significant differences were observed between groups for the final weight, growth increment (GI), cephalothorax length (CL) and the relative weight and width of the pleon (RWeP and RWiP, respectively) (Table 1). These results show that the injection of dopamine produce smaller and less mature ovaries, probably through the inhibition of vitellogenin synthesis. However, this process did not result in an enhanced growth, which could be due to the stress associated to the injection of this neurotransmitter. It would be interesting to evaluate alternative ways of dopamine supply as a next step to eliminate the stress factor.