The food and feeding habits of rocky reef fish of north‐eastern New Zealand

Abstract

The gut contents of 50 species of fish that inhabit coastal rocky reefs of north‐eastern New Zealand were examined. Most of the fish were collected in the vicinity of Goat Island, north of Auckland, by spearfishing, handlines, and rotenone. Food items in the gut were analysed by both percentage occurrence and percentage volume for each species. Their feeding habits are briefly described. An index of use (U), based on the intensity of predation and the number of fish taking the food, was calculated for each food type. The most important foods of rocky reef fishes (U≥0.1) were amphipods, crabs, fishes, gastropods, copepods, errant polychaetes, hermit crabs, and small bivalves. Most rocky reef fishes have broadly generalised feeding habits, and foods taken mainly reflect those organisms of suitable size that are abundant and most readily available. Notable exceptions are sponges, hydrozoans, anthozoans, bryozoans, and ascidians, which, although common, are probably largely unpalatable to fishes. Fishes appear to dominate the carnivore trophic levels of rocky reef communities: 44 species (88%) are carnivores; 1 species (2%) is omnivorous; and 5 species (10%) are herbivores. In terms of biomass, however, herbivorous fishes may comprise a significant proportion of the total standing crop of fishes and their impact on the reef community may be as great as that of invertebrate‐feeding carnivores.