THE IMPORTANCE OF SELECTING FOR SURVIVORSHIP IN GENETIC YIELD IMPROVEMENT PROGRAMS IN CRUSTACEAN AQUACULTURE

Abstract

ABSTRACTMortality between “seeding” and harvest can cause serious loss of production in crustacean aquaculture. When a species is brought under cultivation for its complete life cycle, genetic changes inevitably result from natural selection in the controlled environment (domestication selection). Such changes can, in a properly designed program, lead to a reduction in the variability that is the source of much of the economic loss. Domestication selection resulted in a two‐fold increase in productivity in a model aquaculture program which involved cultivating the estuarine amphipod Gammarus lawrencianus in the laboratory. Approximately 75% of this gain was due to increased survivorship, the remainder to increased growth rate. Domestication selection will be beneficial in any crustacean with similar genetic relationships among the quantitative traits which determine yield. In aquaculture programs designed with genetic stock improvement in mind, it may be advantageous to reduce mortality by domestication selection before beginning conventional selection or inbreeding for individual traits such as growth rate. If this is not done, conventional programs may be counter‐productive because of their concentrating effect on “unfit” genes which are present in the population. Domestication can be accomplished by systematic feedback of progeny from the outgrowth ponds into the broodstock, and/or selection for lifespan, and/or selection for survivorship on a family basis.