HOBSON: FEEDING RELATIONSHIPS OF FISHES 



or evening. It was only occasionally seen at night, 

 perhaps because it avoided our diving lights after 

 dark. 



Six specimens (337: 245-570 mm) were collected 

 at various times of the day. The only one (248 mm) 

 that contained relatively fresh prey (three larval 

 fishes, about 10 mm long, and a number of mysids) 

 was collected 3 h after sunrise. A second indi- 

 vidual (315 mm), taken shortly after noon, con- 

 tained in its stomach, an unidentified fish (about 

 80 mm) and a shrimp, both moderately digested. 

 Three other individuals (245-330 mm) were col- 

 lected late in the afternoon, and their stomachs 

 contained well-digested fragments — in at least 

 one, the fragments of a fish. The last specimen 

 (570 mm) behaved as if sick when speared early in 

 the afternoon, and its gut was empty. Hiatt and 

 Strasburg (1960) found only fishes in the two 

 specimens of this species that they examined from 

 the Marshall Islands, as did Randall ( 1955) in the 

 four specimens that he examined from the Gilbert 

 Islands. 



CONCLUSION. — Caranx melampygus preys 

 on free-swimmirig fishes and crustaceans, 

 probably most often early and late in the day. 



General Remarks on Jacks 



Jacks are major predators on many widespread 

 tropical reefs (e.g. Marshall Islands: Hiatt and 

 Strasburg, 1960; Gulf of Cahfornia: Hobson, 1965, 

 1968a; Florida Keys: Starck and Davis, 1966; 

 West Indies: Randall, 1967). The larger piscivor- 

 ous jacks, like Caranx hippos caninus, are primar- 

 ily crepuscular in the Gulf of California (Hobson, 

 1965, 1968a) and in the Florida Keys (Starck and 

 Davis, 1966). 



Family Lutjanidae: snappers 



As is true of the sea basses, Hawaiian inshore 

 reefs lack native species of snappers, a family 

 whose members are prominent on shallowwater 

 reefs elsewhere in the tropical Pacific (Gosline and 

 Brock, 1960; Randall and Brock, 1960). Only one 

 species of this family was seen regularly on the 

 Kona study reefs during this project. 



Aphareiis fiircatus (Lacepede) — giirutsu 



During the day this solitary predator swims 

 slowly, 1 to 2 m above the reef, with never more 



than a few individuals in any one place. It was not 

 seen at night during this study, perhaps because it 

 avoided our lights. Only once did I see one attack 

 prey: 5 min before sunrise this individual sud- 

 denly broke from its patrolling attitude 2 m above 

 the reef and dived among a cluster of small fishes, 

 mostly pomacentrids, that were in the process of 

 emerging from their nocturnal shelters (see Hob- 

 son, 1972). The success of the strike was undeter- 

 mined, but at the instant of attack all small fishes 

 within a radius of about 15 m shot under cover. 

 Three specimens (253: 244-262 mm) were 

 speared for study. One taken during midafternoon 

 contained a Plagiotremus goslinei, a blenny that 

 swims above the reef only in daylight (see account 

 for this species, below); because this prey was rela- 

 tively fresh, it almost certainly was captured ear- 

 lier that day. Another A . furcatus collected during 

 midafternoon contained moderately digested crab 

 megalops and gammaridean amphipods; although 

 megalops are more typically food of nocturnal 

 predators, the relatively good condition of these 

 small prey indicated they had been collected ear- 

 lier that day. The third A. furcatus, speared 

 during midmorning, was empty. Randall (1955) 

 examined four specimens of this snapper in the 

 Gilbert Islands, and the two with prey contained 

 only fishes. 



CONCLUSION. — Aphareus furcatus preys 

 on free-swimming fishes and crustaceans during 

 daylight. Its habits at night remain unknown. 



General Remarks on Snappers 



\{ Aphareus furcatus hunts prey mostly in day- 

 light, it would seem an atypical lutjanid. Gener- 

 ally lutjanids are described as nocturnal fishes 

 (e.g. Hobson, 1965, 1968a: Gulf of California; 

 Starck and Davis, 1966: Florida Keys; Randall, 

 1967: West Indies). 



The efforts that successfully introduced the sea 

 bass Cephalopholis argus into Hawaiian waters 

 (see account for that species, above) also included 

 the snapperLu(/araus vaigiensis, which now too is 

 well established in Kona. Although L. vaigiensis 

 was not numerous in the study area during this 

 work, one school was seen consistently during 

 daylight on irregular visits to a location in 

 Kealakekua Bay, and soHtary individuals occa- 

 sionally were encountered on the reef after dark. 

 Thus, the habits of this fish appear to be similar to 

 those of certain other species of Lutjanus 



955 



