Cultivated brown mussel (Perna perna) size is reduced through the impact of three invasive fouling species in southern Brazil.
Invasive species reduce the productivity of shellfish mariculture worldwide. Brown mussel culture harvests were examined for invasive species in the state of Santa Catarina – the most important region for shellfish mariculture in Brazil. For the first time, we describe here the impact of the three most abundant invasive species on harvested Perna perna. The ascidian Didemnum perlucidum, the barnacle Megabalanus coccopoma, and the bryozoan Schizoporella errata were all associated with smaller mussel size. Fouled mussels were 19–36% smaller and weighed ~ 60% less than non-fouled mussels. Reductions in mussel size were greatest for shell weight and size when associated with D. perlucidum and tissue dry weight for M. coccopoma. This large reduction in productivity indicates that management of these fouling species should be prioritized to protect the mussel fishery.