lier age determinations had ascribed 

 fish smaller than 245 cm to age group 

 8, whereas their own determinations 

 indicated that 245 cm was roughly 

 equivalent to ages 14-15 for males 

 and age 18 for females. They also 

 asserted that apparent underestimates 

 of the ages offish more than 240 cm 

 long had resulted in estimates of L^ 

 based primarily on data from fish 

 less than 12 years old, which were in 

 excess of any sizes recently recorded 

 for Atlantic bluefin tuna. If their re- 

 sults should be validated, consider- 

 able revisions of recent estimates of 

 the age composition of the Atlantic 

 bluefin tuna stocks (Sakagawa and 

 Coan 1974) would be required. 



Berry et al. (1977) questioned 

 previous age determinations for large 

 Atlantic bluefin tuna. In the size 

 ranges for which they provided aver- 

 age ages (136-181 kg, 181-226 kg. 



227-272 kg, 272-317 kg and 318- 

 362 kg), their ages were 2-3 years 

 less than those of Mather and Schuck 

 (1960), 3-4 years less than those of 

 Butler ( 1 975), and 4-5 years less than 

 those of Caddy et al. (1976). They 

 attributed these discrepancies to the 

 interpretation of growth marks on oto- 

 liths and vertebrae, mainly in fish 

 more than 10 years old. In these older 

 fish, they often found double or mul- 

 tiple markings which, they believed, 

 represented subdivisions of a single 

 year's growth. They assumed that 

 other workers had counted each such 

 mark as representing a year's growth, 

 resulting in a tendency to overesti- 

 mate ages. 



It is most important that the ac- 

 tual age composition of the "relict" 

 population (as described by Caddy et 

 al. 1976) of giant Atlantic bluefin 

 tuna be determined. 



It is also important that the lin- 

 ear growth rate of the early stages of 

 bluefin tuna be determined for the 

 various spawning areas. This infor- 

 mation is needed in terms of length, 

 rather than weight, to permit better 

 estimates of spawning dates and lo- 

 calities from the collection data for 

 these stages of the bluefin tuna. 



Seasonal variations in the growth 

 rates of bluefin tuna up to 4 years old 

 are reasonably well known (Mather 

 and Schuck 1960, Furnestin and 

 Dardignac 1962), but the data now 

 available should permit extension of 

 this knowledge to older ages. The 

 possibility that the growth rate of the 

 Atlantic bluefin tuna has increased 

 as the size of the stock has decreased 

 should also be investigated. This pos- 

 sibility is suggested by the remarkable 

 number of extremely large bluefin 

 caught since 1970 (see Section IV). 



14 



