Figure 3.— Distribution of Tetrapturus angustirostris, occurrence by 1° square (Howard and Ueyanagi, 1965). Shaded lines for 

 delimitation from combined shortbill spearfish and sailfish data from Japanese longline fishery in 1970. 



fishery. This makes it impossible to separate these 

 species and to delineate areas of their distribution in 

 detail. The approximate geographical range in dis- 

 tribution of T. angustirostris is shown in Figure 3. 



2.2 Differential Distribution 



2.21 Spawn, larvae, and juveniles 



Areas of occurrence and seasonal 

 variation: Nakamura (1937) reports that the fish 

 taken in waters adjacent to Taiwan in November 

 released ripe eggs and assumed that spawning of T. 

 angustirostris takes place in winter in warm offshore 

 currents with surface water temperature of about 

 26° C. Fish with ripe ovaries are also reported to occur 

 in the central Pacific Ocean by Royce (1957) and in 

 the western Indian Ocean by Merrett (1971). 



Ueyanagi (1962, 1963a, 1964) assumes from the oc- 

 currence of larvae and mature fish that spawning of 

 this species is more active in winter than in summer, 

 although fish are reported to spawn in the tropical and 

 subtropical waters between lat. 25° N and 25° S. The 

 distribution of larval fish from the western to the cen- 

 tral Pacific Ocean as determined by Ueyanagi is in 

 Figure 4. The larvae were collected from May through 

 February or almost throughout the entire year. The 

 sites of capture of larval fish are concentrated in an 

 area between lat. 15° and 25°N in the western Pacific 

 Ocean, reflecting the increased effort (tows) in this 

 region. From the Indian Ocean, two larval specimens 

 presumably identified as T. angustirostris were 

 reported. They were collected at the Dana station 

 3855 southwest off Sumatra (Jones and Kumaran, 

 1964). Ueyanagi (1962) provides a comparison of the 

 seasonal occurrence of larvae of the shortbill spearfish 



with that of the blue marlin in the western subtropical 

 Pacific Ocean (Table 3). 



For the western Indian Ocean, Merrett (1971) 

 provides some data to indicate spawning of T. 

 angustirostris and states that this species is more 

 abundant during the southeast monsoon season, when 

 the maturity of females is more advanced and the sur- 

 face temperatures are at the lowest (mean 25.5°C). He 

 mentions that this tends to confirm the suggestion by 

 Ueyanagi (1964) that spawning activity is greater dur- 

 ing the winter months. 



2.22 Adult 



Areas of occurrence and seasonal and annual 

 variation: No information on annual variation is 

 available. For seasonal variation, see 2.1. 



Figure 4.— Distribution of larval shortbill spearfish. Black 

 dots from Ueyanagi, 1963a; open circle from Jones and 

 Kumaran, 1964. 



44 



