Sex reversal and growth performance in juvenile females of the freshwater crayfish Cherax quadricarinatus (Parastacidae): effect of increasing temperature and androgenic gland extract in the diet

Monosex male culture of C. quadricarinatus is proposed for increasing yields because males reach a larger size at harvest than females. An experiment was done to evaluate the effects of androgenic gland extract and temperature on sex reversal and somatic growth in early juvenile females. Females were exposed to the following experimental conditions: C: control food and temperature maintained at 26 +/- A 1A degrees C; HT (high temperature): control food and temperature maintained at 28.5 +/- A 1A degrees C; VHT (very high temperature): control food and temperature maintained at 31 +/- A 1A degrees C; AG: food with enriched with androgenic gland (1/10 dose for each juvenile per day) and temperature maintained at (26 +/- A 1)A degrees C. The juveniles were weighed, sexed, and growth increment (GI) and growth rate (GR) were calculated twice a month. The HT and AG groups differed from the C group in GI and GR indicating a greater somatic growth. At the end of the experiment, the HT and AG groups had similar weight but only the HT group had enhanced oocyte diameter, with some vitellogenic oocytes compared to the C group. In the HT group, there was significant sex reversal, as indicated by development of male and intersex male characteristics in different individuals. Both temperature and AG diet have a high potential for culture of this species because of their enhancement of somatic growth; higher temperature increases the proportion of males, a desirable characteristic of cultured populations.