Diet composition and prey selection of the introduced grouper species peacock hind (Cephalopholis argus) in Hawaii

The grouper species peacock hind (Cephalopholis argus) (Serranidae: Epinephelinae), a reef fish predator that is native over most of the IndoPacific region, was introduced to the Main Hawaiian Islands (MHI) in 1956 as part of an introduction program of snapper and grouper species intended to enhance nearshore fisheries (Randall, 1987). Today, this non-native predator occupies a dominant position in the guild of large piscivores on many reefs in the MHI (see Results section). As impacts of piscivores on prey fishes have been demonstrated in a number of studies (e.g., Webster, 2002; Hixon and Jones, 2005), the abundance of C. argus raises the question of how, if at all, it affects native reef fishes in Hawaii. However, the only published study of C. argus feeding in the MHI to date was based on a sample of 10 specimens (Hobson, 1974), which is insufficient to elucidate feeding patterns. Groupers are among the most common predatory reef fishes worldwide (Parrish, 1987). They play an important role in shaping reef communities (Goeden, 1982; Parrish, 1987) and are of large commercial importance in coral reef fisheries (Heemstra and Randall, 1993). However, data on the general feeding ecology of this family remain surprisingly scarce (BeukersStewart and Jones, 2004). In addition, although concern about declines of many grouper species worldwide due to overfishing has led to a renewed research focus on this family (Morris et al., 2000), much of the work to date has concentrated on a limited number of species, e.g., the coral trout (Plectropomus leopardus) in Australia (e.g., Kingsford, 1992; St. John, 1999), the Nassau grouper (Epinephelus striatus) in the Caribbean Sea (e.g., Eggleston et al., 1998), or the dusky grouper (Epinephelus marginatus) in the Mediterranean Sea (e.g., Renones et al., 2002). Most studies of grouper diet have been based on analysis of stomach contents. However, because of the difficulty of obtaining large grouper samples (Beukers-Stewart and Jones, 2004), as well as the high prevalence of empty stomachs due to prey regurgitation during capture and because of the characteristics of grouper feedDiet composition and prey selection of the introduced grouper species peacock hind (Cephalopholis argus) in Hawaii