Comparative analysis of Byssal thread production, mechanical properties, and composition in diploid and triploid Mytilus edulis

Mussel fall-off continues to pose a major challenge for suspension-culture farming, leading to substantial crop losses. Although studies on juvenile mussels (<30 mm) have indicated that triploids may exhibit enhanced byssal thread attachment and reduced fall-off, their performance in adult mussels remains insufficiently explored. In this study, we investigated the production, mechanical strength, biochemical composition, and structural features of byssal threads in diploid and triploid mussels of commercial size (>50 mm). We also calculated metabolic and filtration rates, as well as scope for growth. Our results revealed that triploid mussels produced 25 % more byssal threads with significantly enhanced mechanical properties. Triploid mussels conditioned at 20 °C exhibited a 48 % higher clearance rate, a 57 % greater scope for growth, and a 40 % stronger valve (breaking strength) compared to diploids. These findings suggest that triploid mussels over 50 mm have superior attachment strength relative to wild mussels, primarily due to increased thread production. • Triploids mussels conditioned at 20 °C showed 48 % higher clearance rate and 57 % greater scope for growth. • Triploids mussels had 40 % stronger valve (breaking strength). • Triploids mussels (>50 mm) produced 25 % more byssal threads than diploids. • Threads from triploid mussels had significantly enhanced mechanical properties.