A. BLUE MARLIN. B. STRIPED MARLIN C. SAILFISH 



D. SHORTBILL 



SPEARFISH 



Figure 5. — Head profiles of larvae of four species of Indo-Pacific billfishes, with emphasis 

 on the pterotic and preopercular spines. (Top row — about 4 mm: middle — about 6 mm; 

 bottom — about 8 mm.) 



effective diagnostic characters for larvae generally 

 under 12-13 mm in total length. 



The spines are occasionally found broken on 

 specimens, but this should not deter their use since 

 striped marlin can be reliably identified if there are at 

 least one-half of the pterotic spine and one-third of 

 the preopercular spine left for examination. 



THE LARVAE OF 

 ATLANTIC BILLFISHES 



Although detailed studies were not possible due to 

 the small numbers of larvae available from the Atlan- 

 tic Ocean, it was. however, noted that the features of 

 the pterotic and preopercular spines of the Atlantic 

 species closely resembled those of the related 

 Indo- Pacific species. Namely, the spines on the lar- 

 vae of the Atlantic blue marlin, M. nigricans (Fig. 6), 

 resembled those of the Indo-Pacific blue marlin; 

 those of the Atlantic white marlin. T. albidus (Fig. 

 7). resembled those of the Indo-Pacific striped mar- 

 lin; those of the Atlantic longbill spearfish, T. pflue- 

 geri (Fig. 8). resembled those of the Indo-Pacific 

 shortbill spearfish; and those of the Atlantic sailfish. 



/. albicans (Fig. 9), resembled those of the Indo- 

 Pacific sailfish. Thus it appears that the differentia- 

 tion between the larvae of the Atlantic blue marlin 

 and white marlin can also be made on the basis of 

 these spines. 



VARIATIONS IN PIGMENTATION 



OF THE LOWER JAW 



OF SAILFISH 



Based on five specimens, Ueyanagi (1963) pre- 

 sented a preliminary report on sailfish larvae which 

 lacked the characteristic pigmentation on the pos- 

 terior half of the lower jaw. Since then, additional 

 studies have resulted in the examination of 37 such 



Figure 6. — Larva of the Atlantic blue marlin, Makaira 

 nigricans, 9.0 mm in total length. 



76 



