50 



'A 





«j?. 







Oan 



100 



BODY LENGTH 



200 



Figure 3. — Relationship between spread of caudal fin and 

 body length in sailfish. Open circles show data from the 

 Atlantic sailfish and solid circles show data from the 

 Indo-Pacific sailfish. Data from Vick (1963) and Royce 

 (1957) are included. 



200 cm body length of both species are difficult to 

 observe, because the lateral line system is covered 

 under the thick skin and scales. For specimens less 

 than 100 cm body length of both species, the charac- 

 teristic patterns of the lateral line systems are easily 

 recognized. In the Yaizu Fish Market, which is rec- 

 ognized as the world's largest landing market for 

 tuna longliners, I observed and was able to separate 

 many specimens of M. mazara and M . nigricans on 

 the basis of different patterns in the lateral line sys- 

 tem. With large specimens in which the lateral line 

 was covered, I could not distinguish the species. I 

 consider that the differences in the lateral line sys- 

 tem are important enough to warrant recognition of 

 both species. 



Tetrapturus georgei Lowe was recognized by de 

 Sylva (1972) as a valid species distributed in the 

 western Mediterranean and off Spain and Morocco. 

 Because of lack of specimens I have omitted consid- 

 eration of T. georgei in this paper. 



DISTRIBUTION OF BILLFISHES 



The distribution of the billfishes discussed in the 

 following sections is based primarily on unpublished 

 data obtained from the Japanese longline catches 

 made in the Pacific, Indian, and Atlantic Oceans. 

 These data were made available by the Far Seas 

 Fisheries Research Laboratory, Shimizu. Japan. 

 The fishing grounds of the Japanese longliners ex- 



tend from lat. 50°N to lat. 45°S in the Pacific Ocean, 

 from the northern sectors of the Arabian Sea and 

 Bay of Bengal to lat. 50°S in the Indian Ocean, and 

 from lat. 50°N to lat. 50°S in the Atlantic Ocean. 



Xiphias gladius 



This species is distributed in the tropical and 

 temperate waters of the Pacific, Indian, and Atlantic 

 Oceans. Good commercial fishing grounds are lo- 

 cated in the northwestern Pacific, off the Pacific 

 coast of Mexico, off Ecuador, in the Arabian Sea, off 

 Newfoundland, off southern Brazil, and the Gulf of 



A. 

 B 

 C 



D 





.y 



y— ••.. — "5 — "■" 



3^^;3z:> 



c:~X':: 



E 

 G 



H 



•Y-~ — .^..-.^„.---. 



,.7;« 



•■••\" 



.1- J.. 



Figure 4. — Variations with growth of the lateral line sys- 

 tems of the Indo-Pacific blue marlin (A-G) and the Atlantic 

 bluemarlin(H-J). Body length: A. 17.7 cm, B. 81.0 cm, C. 

 84.3 cm, D. 1 12.9 cm, E. 1 19.5 cm, F. ca. 185 cm, G. ca. 260 

 cm, H. ca. 140 cm, I. 188.0 cm. J. ca. 205 cm. 



49 



