Genetic parameters and genotype-environment interactions for skeleton deformities and growth traits at different ages on gilthead seabream (Sparus aurata L.) in four Spanish regions.

One of the most important problems of fish aquaculture is the high incidence of fish deformities, which are mainly skeletal. In this study, genetic parameters on gilthead seabream (Sparus aurata L.) for skeleton deformities at different ages (179, 269, 389, 539 and 689 days) and their correlations with growth traits were estimated, as were as their genotype × environment interactions (G × E) at harvesting age. A total of 4093 offspring from the mass spawning of three industrial broodstocks belonging to the PROGENSA(®) breeding programme were mixed and on-grown by different production systems in four Spanish regions: Canary Islands (tanks and cage), Andalusia (estuary), Catalonia (cage) and Murcia (cage). Parental assignment was inferred using the standardized SMsa1 microsatellite multiplex PCR. From three broodstocks, 139 breeders contributed to the spawn and a total of 297 full-sibling families (52 paternal and 53 maternal half-sibling families) were represented. Heritabilities at different ages were medium for growth traits (0.16-0.48) and vertebral deformities (0.16-0.41), and low for any type of deformity (0.07-0.26), head deformities (0.00-0.05) and lack of operculum (0.06-0.11). The genetic correlations between growth and deformity traits were medium and positive, suggesting that to avoid increasing deformities they should be taken into account in breeding programmes when growth is selected. The G × E interactions among the different facilities were weak for length and deformity and strong for growth rate during this period. These results highlight the potential for the gilthead seabream industry to reduce the prevalence of deformities by genetic improvement tools.

Development of the first standardised panel of two new microsatellite multiplex PCRs for gilthead seabream (Sparus aurata L.).

The high number of multiplex PCRs developed for gilthead seabream (Sparus aurata L.) from many different microsatellite markers does not allow comparison among populations. This highlights the need for developing a reproducible panel of markers, which can be used with safety and reliability by all users. In this study, the first standardised panel of two new microsatellite multiplex PCRs was developed for this species. Primers of 138 specific microsatellites from the genetic linkage map were redesigned and evaluated according to their genetic variability, allele size range and genotyping reliability. A protocol to identify and classify genotyping errors or potential errors was proposed to assess the reliability of each marker. Two new multiplex PCRs from the best assessed markers were designed with 11 markers in each, named SMsa1 and SMsa2 (SuperMultiplex Sparus aurata). Three broodstocks (59, 47 and 98 breeders) from different Spanish companies, and a sample of 80 offspring from each one, were analysed to validate the usefulness of these multiplexes in the parental assignation. It was possible to assign each offspring to a single parent pair (100% success) using the exclusion method with SMsa1 and/or SMsa2. In each genotyped a reference sample (Ref-sa) was used, and its DNA is available on request similar to the kits of bin set to genotype by genemapper (v.3.7) software (kit-SMsa1 and kit-SMsa2). This will be a robust and effective tool for pedigree analysis or characterisation of populations and will be proposed as an international panel for this species.