Genetic monitoring of broodstocks of the marine shrimp Litopenaeus vannamei in a closed rearing system in Pernambuco, Brazil

Abstract

Loss of genetic variability can be detrimental to apopulation’s survival traits and ¢tness. These e¡ectsare likely to be maximized in shrimp closed brood-stock rearing systems where post-larvae are oftenproduced from crosses of breeders collected from anassociated grow-out farm after mass selection. Long-time broodstock management in closed systems isalso expected tolead to reduction inorevencompleteeradication of genetic variability. The present workaimed at monitoring the genetic variability of aLitopenaeus vannameihatchery in the state of Per-nambuco (Brazil), during three successive replace-ments, using microsatellite markers. No signi¢cantgenetic diversity losses have been observed throughthe values of mean heterozygosity (Ho50.460 andHe50.660 in the ¢rst sample;Ho50.420 andHe50.620 in the second sample; andHo50.600andHe50.660 in the third sample). However, somealleles appear to have been lost after three replace-ments. The diversity level was considered to be highand is comparable to those reported for wild popula-tions, suggesting that the original imported founderstock of BrazilianL. vannameiis likely to have hada high genetic diversity, possibly due to multipleorigins