Gill rakers 31-40, more numerous than in any 

 other species of Thunnus except T. thynnus. 



Liver with striations on ventral surface, its three 

 lobes subcfjual in length, and with vascular cones on 

 its dorsal side (as in T. alalunga, T. obrsus, and T. 

 Ihynnvs). Spleen located on right side, and stomac-h 

 on left (as in all except T. alalunga). Kidney with 

 a very short "tail," reaching to the level of vertebra 

 8-12 (as in T. Ihynnus). 



Cutaneous arteries originating at level of vertebra 

 4-5, passing laterally between ribs 2 and 3 or 3 and 4, 

 and dividing between intermuscular bones 4 and 5 

 (as in T. alalunga and T. thynnus). Two rows of 

 arterioles and venules arising from each main lateral 

 cutaneous branch (as in T. obcsus and T. thynnus). 

 Post-cardinal vein absent (as in T. alalunga and T. 

 thynnus). 



Posterior parasplienoid margin forming an angle, 

 becoming acute in large specimens (as in T. alalunga, 

 T. thynnus, and, to a lesser tlegree, in T. obcsus), 

 occasionallj- rounded in small specimens. Alisphe- 

 noids extending far ventrad into orbital cavity; dis- 

 tance from most ventral part of alisphenoid to near- 

 est point on parasphenoid goes into greatest height 

 of anterior part of orbit two times or more (only T. 

 thynnus and larger specimens of T. tonggol have a 

 similar condition). Alisphenoids not known to fuse 

 with parasphenoid as is the case in some T. thynnus. 

 Subopercle relatively slender, its upper anterior mar- 

 gin usually almost vertical in its lower two-fifths or 

 more, sloping jjosteriad in its upper portion (as in 

 T. thynnus); rarely, there is no vertical portion. 



Vertebrae 18 + 21 (as in all except T. atlanlicus). 

 First ventrally directed parapophysis on vertebra 9 

 (as in all except T. thynnus and T. tonggol). First 

 closed haemal arch on vertebra 10 (as in T. alalunga, 

 T. thynnus, and, rarely, all others except T. tonggol). 

 Anterior haemal prezygapophyses arising high on 

 haemal arch (as in T. alalunga, T. thynnus, and T. 

 obcsus). All haemal postzygapophyses short, less 

 than half centrum length (as in T. alalunga, T. 

 thynnus, and T. obesu.s). \>ntrolateral foramina 

 small, not more than one and one-half times width 

 of haemal spine (as in T. alalunga, T. thynnus, and 

 7'. obcsus). 



C'omijarisons with T. thynnus are given in table 5. 



Range 



Thunnus maccoyii is apparently mainly restricted 

 to the Southern Ocean, although it is impossible to 

 evaluate many records. This species is best recog- 



nized at present by skeletal characters, although the 

 yellow caudal keel is also diagnostic. We have 

 examined skeletal material from Tasmanian waters 

 reported bj' Godsil and ?Iolmbcrg (1950); from west- 

 ern South Africa, reported by Talbot and Penrith 

 (19(33); additional specimens from the Sydney, Aus- 

 tralia, market; from west of southern Australia; and 

 from off the coast of Chile. The presence of T. 

 maccoyii in the Pacific and Indian oceans off both 

 sides of southern Australia and off Chile, and in the 

 Atlantic off South .\frica is thus definitely estal)- 

 lished. The geographic distril)ution summarized 

 by Robins (19G3) included waters north of New 

 Zealand and areas off western Australia north almost 

 to the Indonesian Islands. These records are prob- 

 ably correct, but need confirmation through osteo- 

 logical studies. Southeastern Pacific catches arc 

 reported by Jajmnese expeditions (Japan Fishery 

 Agency, 1964). If these unconfirmed records are 

 accepted, it seems likely that T. maccoyii will be 

 found throughout the Southern Ocean south of 30° S. 



THUNNUS THYNNUS (Linnaeus, 1758) 

 BLUEFIN TUN.\ 



The synonymy of each of the two subspecies is 

 presented separately. The diagnosis of the species, 

 discussion of nominal species and subspecies, and 

 summary of the range consider both subspecies. 



THUNNUS THYNNUS THYNNUS (Linnaeus, 1758) 

 ATLANTIC BLUEFIN TUNA 



Scomber pinnulis oclo ncl novem, in extremo dorso ex 

 sulco ad pinnus vrntralcs Artedi, 1738a: 31 (descrip- 

 tion) and 1738b: 141-142 (references to Aristotle, 

 Ovid, Pliny, etc.). 



Scomber thynnus Linnaeus, 1758: 297-298 (original 

 description; based on Artedi, 1738). Bonnaterre, 

 1788: 139, pi. 58, fig. 228. Gmelin, 1789: 1330- 

 1331 (description, synonymy). LacC'pede, 1800: 

 598, ()05-()32 (description, synonymy). Ilisso, 

 1810: 163 (Nice). 



Thymius thynnus, Cuvier, 1817: 313 (Mediter- 

 ranean). Giinther. 1860: 362-363 (synonymy, 

 description; Atlantic and Mediterranean). 



Thynnus mediterraneus Risso, 1826: 414-415 (substi- 

 tute name for Scomber thynnus Linnaeus, 1758; 

 Nice). 



Thynnus vulgaris Cuvier in Cuvier and Valenciennes, 

 1831 : 42-71 (substitution of new name for Scomber 

 thynnus Linnaeus, 1758), pi. 210. 



116 



U.S. FISH AND WILDLIFE SERVICE 



