dorsal spines and fin rays are 51 + 6. The grooves in 

 which the first dorsal fin and the first anal fin are fold- 

 ed are formed throughout the entire base of each fin. 

 The length of the pectoral fin nearly equals the height 

 of the body. The ventral fins are considerably 

 elongated, reaching the vicinity of the anus. The ven- 

 tral groove in which the ventral fins are folded is 

 developed. The spread of the caudal fin is not large 

 compared with that of the adult. The space between 

 the anus and the origin of the first anal fin is large, 

 reaching about 26% of the length of the body cavity. 



The body cavity is extremely long, extending to the 

 first anal fin beyond the anus. The arrangement of the 

 viscera is almost identical with that in the adult. 

 Although completely immature, the left lobe of the 

 gonad is longer than the right lobe, and elongated a 

 little beyond a point at which the right lobe joins. 



Scales cover the opercle and the whole surface of 

 the body. They are cycloid with less exposed portion 

 and appear to be at the early stage of development. 

 The shape of the scales depends on the location of the 

 scales on the body; those on the dorsal and the ventral 

 parts are slender compared with those on the lateral 

 part of the body. The lateral line is simple: it starts 

 above the pectoral fin, being bent downward and run- 

 ning straight along the lateral median line from a 

 point posterior to the pectoral fin to the caudal pedun- 

 cle. 



Sun (1960) reported on a juvenile specimen he iden- 

 tified as T. angustirostris from the Pacific Ocean. 

 Ueyanagi (1962), however, believes this specimen to 

 be the young form of Eumakaira nigra (= Makaira 

 mazara), the Pacific blue marlin, in the light of 

 features such as the remarkable shortness of the 

 snout, the evenly high dorsal fin throughout its entire 

 base and the form of the lateral line. 



3.3 Adult Phase 



3.31 Longevity 



Nakamura (1938) states that fish over 20 kg are 

 rare. Royce's (1957) largest specimen weighs 51 

 pounds (about 23 kg) and measures 1,859 mm from 

 the bill tip to the caudal fork. According to the length 

 composition of the South Pacific shortbill spearfish 

 reported by Koga (1959), the largest fish is in the 151- 

 to 155-cm (eye-fork length) class for males and in the 

 146- to 150-cm class for females. The largest specimen 

 ever reported is a fish of 114 pounds (about 51.8 kg) 

 given in Table 3 of Royce's paper (1957). This fish was 

 landed at the Honolulu market in 1951. 



3.32 Hardiness 



Nothing has been reported on hardiness. Since 

 billfishes are large and active dwellers of the ocean, 

 their life will no doubt be very short in artificially con- 

 fined environments. When hooked on longline gear, 

 they often jump up above the sea surface, thrash 



violently and eventually entangle themselves with 

 branch lines into almost exhaustion before they are 

 landed. 



3.33 Competitors 



Billfishes, together with tunas, constitute a group of 

 apex predators in tropical and subtropical waters. 

 They appear to compete with one another in feeding, 

 since previous reports (Suda, 1953; Yabuta, 1953; 

 Watanabe, 1960; Koga, 1967; Mori, 1967 4 ) indicate 

 that they have no marked food preference and there is 

 no significant differences in their stomach contents. 

 Sharks or other kinds of fishes such as dolphins, 

 barracudas, Spanish mackerels also probably com- 

 pete in feeding with tunas and billfishes. 



3.34 Predators 



When hooked on longline gear, it is well known that 

 tunas and billfishes are frequently attacked by sharks 

 or perhaps killer whales. Although information is 

 lacking, sharks and killer whales probably prey on 

 tunas and billfishes. 



3.35 Parasites, diseases, injuries, and 

 abnormalities 



No information is available. 

 3.4 Nutrition and Growth 

 3.41 Feeding 



Information is scarce on diel feeding habits, 

 manner, frequency, and variation of feeding habits in 

 relation to environmental and physiological con- 

 ditions. Yabuta (1953) notes that different kinds of 

 food organisms tend to appear in stomachs of tunas 

 and billfishes including T. angustirostris as the season 

 changes. It has not been determined, however, 

 whether this difference is due to the difference in fish 

 species from which stomachs were collected or to 

 other reasons. 



3.42 Food 



Types eaten and their relative importance in the 

 diet: The stomach contents of billfishes comprise a 

 very large variety of Crustacea, mollusca, tunicata, 

 pisces, and coelenterata. Of the food items, squid and 

 fishes are the most important in frequency and 

 number (Suda, 1953; Yabuta, 1953; Watanabe, 1960; 

 Koga, 1967; Mori, 1967 (see footnote 4); Koga, 

 Imanishi, and Tawara, 1972). These reports agree in 

 that the billfishes, as do tunas, feed on commonly pres- 



'Mori, K. 1967. Interim report on the investigation of stomach 

 contents of billfishes. Report presented at Tuna Fisheries Research 

 Meeting, 1966, 5 p. 



48 



