Genetic quality deterioration in captive developed broodstocks of Macrobrachium rosenbergii revealed by allozyme electrophoresis

Abstract

Broodstocks were produced in captive condition (Project developed broodstock, PB) by rearing
river origin juveniles of M. rosenbergii and their performance was compared with Halda river origin
broodstock (HB) and Gher developed broodstock (GB). Berried females from all the broodstocks were bred in
a hatchery and their F1 progenies (F1HB, F1PB and F1GB) were produced. Genetic variation of the three
broodstocks and their F1 progenies of M. rosenbergii were assessed by allozyme electrophoresis. Genetic
variability was higher in two wild origin broodstocks (HB and PB) than others. Genetic variability reduced in
all F1 progenies. The values of pairwise Fst (0.0355) and genetic distance (0.047) between two wild origin
brood-stocks (HB and PB) were lowest indicating their close relationship which was also evident through
dendrogram. Separation of their F1 progenies (F1HB and F1PB) by forming another sub-cluster in dendrogram
supports the occurrence of genetic change in F1 generation. Decline of effective breeding number (Ne) in
F1HB and F1GB as compared to their parents indicated occurrence of inbreeding in F1 generation. The present
study revealed that hatchery managers should not use captive origin broodstocks year after year rather broods
should be produced in every year by rearing wild PL or juveniles with appropriate brood management
techniques.