ESTIMATES FOR THE HERITABILITY OF SIZE IN JUVENILE PENAEUS-MONODON PRAWNS FROM HALF-SIB MATINGS

Eighteen half-sib groups of the giant tiger prawn, Penaeus monodon, we re obtained using artificial insemination of two females by each male. The total length (mm) and wet weight (mg) of the young were measured at 6 and 10 weeks after hatching. Sire component estimates were approx imately 0.10 for both total length and wet weight at each age. Dam com ponents were greater suggesting large non-additive genetic effects and /or common environment effects that could not be differentiated on the available data. A reduction in the dam component for both total lengt h and wet weight from approximately 0.5-0.6 at 6 weeks to 0.3-0.4 at 1 0 weeks suggested significant maternal effects were present. The resul ts emphasised the strong environmental controls on prawn growth, parti cularly potential maternal effects that are likely to play a role earl ier in development. These influences resulted in highly variable data, emphasising the need for higher degrees of replication of sire and da m groups in order to detect significant sire effects in P. monodon. (C ) 1997 Elsevier Science B.V.