I. INTRODUCTION 



The objective of this worlc is to 

 review and summarize available infor- 

 mation on the fisheries, distribution, 

 and other aspects of the Hfe history of 

 the Atlantic bluefm tuna, Thunmts 

 thynnus thyimus (Linnaeus 1 758) (Fig- 

 ure 1). The need for such a review is 

 emphasized by the concern over the 

 staUis of the Atlantic bluefin tuna stocks 

 and the recent enactment of measures 

 for the conservation of this species by 

 the International Commission for the 

 Conservation of Atlantic Tunas 

 (ICCAT). 



The wastefulness of harvesting 

 Atlantic bluefin tuna at extremely small 

 sizes was recognized intuitively by 

 d' Amico ( 1 8 1 6, cited by Pavesi 1 887). 

 Sicilian laws of 1 796 and 1 80 1 prohib- 

 ited the catching of small bluefin tuna 

 (Avolio 1805 in Parona 1919). This 

 restriction was apparently dropped dur- 

 ing revisions of Italian fishery regula- 

 tions in 1877 and 1882 (Pavesi 1887), 

 but a minimum size limit of 60 cm was 

 imposed in 1927 (Mussolini and 

 Belluzzo 1927). In the 1960s, a mini- 

 mum size limit of 90 cm was in effect 

 in Italy (Sara 1968, Miyake 1976, 

 Maldura 1965). 



The effect of harvesting bluetln 

 tuna at small sizes was estimated theo- 

 retically by Shingu et al. (1975) and 

 empirically by Mather (1974). Both 

 works indicated that the capture of one 

 thousand tons of young bluefin tuna 

 precluded the subsequent capture of 

 many thousand tons of larger individu- 

 als. 



Action in 1 975 by ICCAT in regu- 

 lating the bluefin tuna fisheries finally 

 recognized in principle the need to man- 

 age the fisheries for this economically 

 important species. The regulations 

 which became effective August 10, 

 1975, are as follows (Miyake 1975): 



First — That the contracting par- 

 ties take the necessary measures to pro- 

 hibit any taking and landing of bluefin 

 tuna (Thunnus thynnus thynnus) weigh- 



ing less than 6.4 kg. Notwithstanding 

 the above regulation, the contracting 

 parties may grant tolerances to boats 

 which have incidentally captured blue- 

 fin tuna weighing less than 6.4 kg, with 

 the condition that this incidental catch 

 should not exceed 15% of the number 

 offish per landing of the total bluefin 

 tuna catch of said boats or its equiva- 

 lent in percentage by weight. 



Second — That as a preliminary 

 step, the contracting parties that are 

 actively fishing for bluefin tuna 

 ( Thunnus thynnus thynnus) or those that 



ment (National Marine Fisheries Ser- 

 vice, 1975, 1976) Canada, France, and 

 Japan have also put the ICCAT regula- 

 tions into effect (Caddy and Burnett 

 1976, Kume 1976, 1977). 



Whether these regu lations were en- 

 acted in time, and are adequate to re- 

 store the Atlantic bluefin tuna fisheries 

 to their potential and former impor- 

 tance, is questionable. It is certain, hovy- 

 ever, that better knowledge of the life 

 history of the bluefin tuna is a prerequi- 

 site to effective management of its fish- 

 eries. By general consensus, knowl- 



Figure 1. Atlantic bluefin tuna {Thunnus thynnus thynnus). 



incidentally catch it in significant quan- 

 tities shall take the necessary measures 

 to limit the fishing mortality of bluefin 

 tuna to recent levels for a period of one 

 year. At the 1975 meetings of the 

 ICCAT Commission, this second item 

 was extended for an additional two 

 years, with provision for its review at 

 the 1976 meetings of the ICCAT Coun- 

 cil. 



The member nations are respon- 

 sible for enforcement of ICCAT regula- 

 tions within their territorial waters. For 

 the United States, the Atlantic Tunas 

 Convention Act of 1975 empowered 

 the Secretary of Commerce to imple- 

 ment regulations established by ICCAT. 

 The National Marine Fisheries Service 

 (NMFS) drew up a set of regulations, 

 and is responsible for their enforce- 



edge of stock identity and migratory 

 patterns is of prime importance. 



The aspects of the fisheries and 

 life history herein discussed include: 

 age and growth information; catch sta- 

 tistics; size, sex, and age composition 

 of the landings in various areas; spawn- 

 ing and development; migration; and 

 stock identification. Environmental pa- 

 rameters and their possible influences 

 on the distribution, migrations and 

 spawning of the species are also con- 

 sidered. Hypotheses on the migrations 

 of bluefin tuna and stock identity are 

 discussed. Finally, we state our own 

 conclusions in regard to these matters 

 and make some recommendations for 

 future research. 



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