Heritability estimation for okadaic acid algal toxin accumulation, mantle color and growth traits in Mediterranean mussel (Mytilus galloprovincialis)

Mediterranean mussel (Mytilus galloprovincialis) is one of the main species of the European aquaculture, Galicia being (NW Spain) the main productive region (~ 200,000 t/year). The main problem for mussel production is the accumulation of toxins coming from microalgae blooms, which have even increased in recent years determining the banning of commercialization for long periods. We estimated the heritability and correlations (genetic and phenotypic) for toxin concentration after a toxic episode related to the main diarrheic toxin, okadaic acid, and after a depuration period at indoor facilities using a large amount of full-sib (170) and half-sib families (above 600 both via father and via mother). We took advantage of the experimental design to estimate the same parameters for other relevant traits for mussel production like growth-related traits and color. Heritabilities were moderate and significant after both the accumulation and detoxification periods (h2 ~ 0.35), suggesting the possibility of reducing toxin concentration through breeding programs in mussels. Growth-related traits also showed moderate heritabilities (~ 0.30), while color showed a very high heritability (~ 0.90), making them suitable for selection depending on producer and consumer demands. Interestingly, growth-related traits showed negative and significant genetic and phenotypic correlations with toxin concentration, while color showed positive ones, strongly suggesting that bigger and whitish mussels may accumulate less toxin. The results of our study support the viability of breeding programs to face the main problems of mussel industry, but this approach will determine a change in seed production, the wild seed being replaced or complemented with hatchery-produced seed.