Parentage assignment, estimates of heritability and genetic correlation for growth-related traits in meagre Argyrosomus regius

Abstract Meagre is a relatively new aquaculture species with great potential in large scale European aquaculture. The primary objective of the study was to describe, for the first time, parentage allocation and assign offspring to their parents for an industrial scale production system. A total of 800 meagre fish were sampled from two large cages in January and May 2016, both part of a commercial farm site in Valencia, Spain. All fish originated from the same spawning event obtained from a broodstock of 6 females and 13 males. However, due to differential growth during the juvenile stage the fish were graded into two groups, a group of larger juveniles that was transferred to one cage (batch 1) and a group of smaller juveniles that were transferred to the second cage (batch 2). Total length and weight was measured for all fish that were genotyped with a 10 microsatellite loci multiplex to infer parentage based on parental genotypes. Parentage assignment rate was high (87.5% for batch 1 and 95% for batch 2) and provided evidence that offspring belonged to 20 families. Half of the broodstock was identified as probable parents of the offspring (five females and seven males).Between the two sea-cages, a slight differential composition for the same families was encountered. The fifteen shared families that the offspring were assigned to, were analyzed for statistical significant differences concerning body weight and total body length, differences which were observed in 3 families for both batches. We estimated the heritability for body weight and total body length, as well as the genetic and phenotypic correlations for these two traits. Batch 1 showed higher heritability estimates than batch 2 with the genetic and phenotypic correlation estimates being almost the same for both batches. Certain parents contributed more offspring and exhibited dominance in spawning. Similarly, the growth related traits of body weight and total body length of the dominant parents correlate, putatively, with the statistical important differences that are observed in these three families.