The case for all-female freshwater prawn, Macrobrachium rosenbergii (De Man), culture

The prevailing notion in the prawn (Macrobrachium rosenbergii) culture industry is that the large male prawns that dominate the product value in research and commercial populations should, alone, be the target of commercial mono-sex (all-male) culture. However, studies have shown that the male prawn's response to increasing density (intensification) is controlled by a strong hierarchical dominance-based social structure resulting in a large, disproportionate, increase in low value small animals in the lower modal class of the male prawn size distribution. In contrast, prawn females and other aquatics, such as marine shrimp, display a moderate and uniform response to intensification in all size classes. Indeed, the densities in which prawn male superiority has been demonstrated are well below those used in intensive marine shrimp culture. This article: (1) discusses the background to the issue, (2) discusses the notion that because female prawns appear to be marine shrimp-like with a normal size distribution indicating a lack of a strong social dominance this will render them superior to all-males under intensive growing conditions, (3) presents a rate-of-response-to-density model projecting a female-superior response to high previously untested densities, (4) summarizes results of a pond field test conducted at Auburn University (Auburn, AL, USA) to test the model's results whereby hand-sexed prawns in treatment-replicated in-pond cages at densities of 10, 25, 40 and 55/m2 showed that all-female prawns give higher production and product value than males under intensive conditions, (5) discusses the use of biotechnological methods to sex-reverse brood-stock to produce all-females and (6) discusses the notion that the potential of genetic selection to increase prawn production is only possible using females.