Diet, feeding behaviour, activity and predation of the temperate blue-throated wrasse, Notolabrus tetricus

Abstract

Notolabrus tetricus is a generalist carnivore with a preference for molluscs and crustaceans—small molluscs and amphipods at small wrasse size, and larger molluscs and crabs with increasing size. Dietary overlap between three adjacent 10 cm size groups is high. No-choice, two-species-choice and multiple-choice field experiments showed that, within the Mollusca, the wrasse prefers chitons and abalone to other gastropods and limpets;crabs and shrimps are high, and echinoderms are low, on the preference list.

A comparison of prey consumed with the relative abundance of prey groups shows that the wrasse takes prey more or less in proportion to its abundance, with variation in this pattern attributed to prey defences and predator choice. A long-term study showed that per capita consumption of cryptic abalone increased with increasing abalone density, suggesting a functional response of wrasse to the density of a preferred prey. The wrasse is a diurnal predator with a defined home range that increases with increasing size of wrasse. Foraging activity commences soon after dawn, reaches a peak during mid morning, declines during the afternoon, and ceases at dusk. Inter-and intra-specific agonistic interactions are few and size-related. The functional importance of this wrasse in rocky shore systems is considered.