Size-selective predation of the catfish Pimelodus pintado (Siluriformes: Pimelodidae) on the golden mussel Limnoperna fortunei (Bivalvia: Mytilidae)

Abstract

ABSTRACT. This paper describes the size-selective predation on Limnoperna fortunei (Dunker, 1857) by Pimelodus pintado (Azpelicueta, Lundberg & Loureiro, 2008) fortunei was found to be the most important food item of P. pintado. The variation in length of the mussels (0.7-3.2 cm, with a mode of 1.3 cm) indicates that the species is now fully established in the system. Our data indicates that large individuals of P. pintado incorporate more mussels in their diets than small individuals. However, regardless of their size, P. pintado individuals predate only on small (<1.4 cm) representatives of L. fortunei. This prey size corresponds to a phase when the mussel is more mobile and readily available for fish. Larger, more aggregated prey groups that are attached to hard substrates are avoided by fish predators.