Indirect selection for growth and life-history traits in Indian carp aquaculture: 1. Effects of broodstock management

Artificial selection for genetic improvement is not carried on in Indian fish hatcheries. However, the process of selection of potential breeders and artificial propagation involves indirect selection, the nature of which will be determined by the type of breeders selected for breeding.The present study is focused on females belonging to two carp species, Labeo rohita and Cirrhinus mrigala, from two fish farms in Karnataka State, south India. Quantitative estimates of pre-reproductive growth rate, age at first spawning and size at first spawning were obtained by a confirmatory factor analysis of measurements made on fish scales. Phenotypic correlations and the resulting correlated selection intensities during a single episode of selection have been estimated. The intensity of indirect selection was negative for pre-reproductive growth rate and positive for age at first spawning. This indicates an undesirable tendency to breed slower growing and later maturing individuals in both farms.