15^th Asia-Pacific Biotechnology Congress

Crustacean monosex aquaculture is advantageous since most species exhibit dimorphic size variation between males and females. In the case of the freshwater prawn, Macrobrachium rosenbergii, intensification of mixed cultures encounters difficulties due to the complex social structure, in which large dominant males are territorial and inhibit the growth performance of the rest of the population. Females on the other hand are less aggressive, less territorial and are suggested to exhibit a relatively homogenous size which does not require selective harvests during or in the end of the grow-out period. In the present study, a novel biotechnology to achieve M. rosenbergii monosex female populations was developed. Our biotechnology includes the following three steps: (1) a single injection of suspended hypertrophied androgenic gland cells (hAG cells) induced fully functional sex-reversal of females into ‘Neo-Males’ bearing the feminine WZ genotype; (2) crossing neo-males with normal females (WZ), yielded progeny containing ~25% WW females as validated by specific DNA sex markers and (3) WW females were crossed with normal males (ZZ) and gave rise to all-female progenies. This biotechnology enabled the first ever large-scale field study showing better performance for all-female prawn culture than mixed culture in all parameters including: Higher survival rate, higher yield per hectare and uniformity of marketable product size. Additionally, no males or egg carrying females were found while examining the harvest of tenth of thousands animals in the all-female ponds. The latter result points at the reliability of our technology to achieve all-female populations and its sustainability with respect to the non-reproductive nature of the monosex culture securing both protection of proprietary elite lines and avoiding environmental invasions by escapees.