II. METHODS AND DEFINITIONS 



A. METHODS AND MATERIALS 



Personal research by the authors 

 during 1950-1976 has produced much 

 of the knowledge which is summarized 

 herein. Extensive additional informa- 

 tion was obtained from the literature, 

 by participation in meetings, and 

 through correspondence and conversa- 

 tions with scientists, fishery experts, 

 and fishermen. 



The authors and their colleagues 

 obtained a great mass of data and infor- 

 mation on the species and its fisheries 

 directly. They examined the landings 

 and often observed or participated in 

 the operations of various commercial 

 and recreational fisheries over a great 

 geographical range. They also partici- 

 pated in many exploratory fishing 

 cruises of U.S. and foreign research 

 vessels. 



The Cooperative Game Fish Tag- 

 ging Program of the Woods Hole 

 Oceanographic Institution (a joint pro- 

 gram with the National Marine Fisher- 

 ies Service since 1973), initiated by the 

 senior author in 1954, has provided 

 much of the information on migrations 

 and mortality rates of Atlantic bluefm 

 tuna. Exchange of information and co- 

 operation with marking programs of 

 other nations has been extensive. 



Also, much information has been 

 obtained through participation in meet- 

 ings of a variety of groups. These in- 

 clude international regulatory agencies 

 and advisory groups, such as ICCAT, 

 the Panel of Experts for the Facilitation 

 of Tuna Research of the Food and Ag- 

 riculture Organization (FAO) of the 

 United Nations, and national, regional 

 and state fishery agencies. We have 

 also attended numerous meetings of 

 non-governmental research and fish- 

 ery groups or associations. 



Further knowledge was obtained 

 by correspondence and conversations 

 with representatives of agencies of the 

 types mentioned above, and with indi- 



viduals concerned with the Atlantic 

 bluefm tuna in many areas and several 

 nations. 



An important additional source of 

 information was a thorough search of 

 the literature. This was most intensive 



B. DEFINITIONS 



1. Bluefm Tuna 



The subject of this paper is the 

 Atlantic bluefin tuna, Thunnus thynnus 

 thynnus, as distinct from the southern 



Fork Length 



Figure 2. Fork length measurement. 



at the initiation of our studies and has 

 been continued since then to the extent 

 that time has permitted. This experi- 

 ence has enabled us to locate many 

 important and little known references. 



Our extensive contacts and data 

 sources, increasing over the years, have 

 enabled us to maintain close connec- 

 tion with the entire Atlantic bluefin 

 tuna situation. 



In the course of our investigations 

 it became increasingly apparent that 

 this species cannot be studied success- 

 fully on a piecemeal or limited area 

 basis. Our approach, therefore, has been 

 an attempt to observe and describe the 

 species and its fisheries over its entire 

 geographic range and during each stage 

 of its life cycle. Our methodology has 

 been a combination of original research 

 and a review of the findings of other 

 investigators in all the nations con- 

 cerned with Atlantic bluefin tuna. 



bluefin tuna, Thunnus maccoyii 

 (Castelnau 1872) and the Pacific blue- 

 fin tuna, Thunnus thynnus orientalis 

 (Temminck and Schlegel 1844). The 

 ranges of the Atlantic and the southern 

 bluefins overlap off South Africa and 

 in the South Atlantic, whereas those of 

 the Atlantic and the Pacific bluefins are 

 apparently separate (Gibbs and Collette 

 1 967, Talbot and Penrith 1 968, Fisher- 

 ies agency of Japan 1974, 1975, 1976, 

 1977). 



Throughout this report, the terms 

 Atlantic bluefin tuna, bluefin tuna, blue- 

 fin, tuna, fish, and individual refer to 

 Thunnus thynnus thynnus unless other- 

 wise identified. 



a. Length 



The most widely used measure- 

 ment of length for bluefin tuna over 1 2 

 cm is fork length (FL). This is the 

 straight line length, measured by cali- 

 pers or equivalent instruments, from 



