A parentage study using microsatellite loci in a pilot project for aquaculture os the European anchovy Engraulis encrasicholus

Abstract

The European anchovy Engraulis encrasicolus L. is in high demand as a fish species, but most fishery stocks are currently at risk of collapsing. A pilot project for anchovy aquaculture was carried out in Spain to explore the potential of satisfying demand for fresh and canned fish and to establish a supportive breeding program that could enhance native populations. We have studied the spawning dynamics in this novel culture using microsatellite loci. Our main aims were to assess the effective breeding number (Ne) and the inbreeding coefficient that would result in use of these fish for an E. encrasicolus closed-cycle culture. A total of 183 wild breeders from the Bay of Biscay were adapted to culture and induced to spawn from November 2009 to January 2010. Two hundred and eighty-eight eggs were collected at four different times. Breeders and eggs were analyzed with two multiplex PCRs that included seven microsatellite loci. Breeders showed extremely high levels of genetic variation (mean number of alleles by locus = 35), but there was a significant reduction in genetic variation in progeny. Breeders were also found to be genetically different from all progeny. Parentage was successfully assigned at a rate of 93%. A total of 105 breeders (55 females and 50 males) took part in reproduction; however, there was significant unequal breeder contribution to progeny. Taking this into account, we found inbreeding coefficients and effective breeder numbers as follows: initial November ∆F = 6.5%, Ne = 8; mid-November ∆F = 2.9%, Ne = 17; December ∆F = 3.2%, Ne = 16; January ∆F = 3.5%, Ne = 14 and overall ∆F = 1.8%, Ne = 27. We have concluded that the partial dominance of some breeders and the high family variance found in this study should be taken into account when establishing closed-cycle cultures of the European anchovy to help guarantee its sustainability. If one of the main goals is establishment of a supportive breeding program to enhance wild stocks, the inbreeding levels found here, which imply significant genetic differentiation between breeders and progeny, should also be taken into account to avoid genetic damage to wild populations over time.