Caddy et al. (1976), using otoliths 

 from 225 large (over 220 cm long 

 and 230 kg in weight) bluetm tuna 

 taken in Canadian waters in the sum- 

 mer and fall of 1975, produced pre- 

 liminary size for age data for fish up 

 to 15 years old. They also calculated 

 the following parameters for von 

 Bertalanffy growth curves (Figure 

 5) for males and females: 



Males Females 



K 0.134 0.116 



L 286.64 277.315 



CD 



t 0.3278 0.7999 



Additional growth and size at 

 age data have been obtained from the 

 lengths at release and recapture for 

 three tagged fish which had been at 

 liberty for periods of 13-14 years. 

 (Table 3) (Mather 1980). Points cor- 

 responding to these sizes have been 

 plotted with the growth curves of 

 Butler et al. ( 1 977) (Figure 5). All of 

 the points lie very near the curve of 

 Butler et al. (1977) for male bluefin. 

 Although the sexes of these recap- 



Table 3. Growth and sizes of three tagged fish recaptured after periods of 13-14 

 years at liberty. 



Return 

 Number 



Release 



Length 

 (cm) 



Age" 

 (years) 



^■ears at 

 Liberty 



Recapture 



Age 



(years) 



Length 



(cm) 



Weight 



(kg) 



' Assuming birth date June 1 (Richards 1976) and ages as estimated by Mather 



andSchuck 1960. 

 Estimate coinciding with modal size of 2 1 fish caught on same longline set. 

 Measurements converted to "caliper" length from "tape" length, assuming: 



caliper length = .958 tape length. 



tured t1sh were not determined, the 

 agreement between results obtained 

 mainly by direct methods and those 

 obtained from counts of age marks 

 on otoliths is good. 

 The results of some of the more im- 

 portant studies of the sizes at ages of 

 Atlantic bluefin tuna are shown in 

 Table 4. 



Age (Ytort) 



JO 



Figure 5. Fits of von Bertalanffy growth curves to mean fork length at age (as 

 determined from otolith readings) for male and female bluefin tuna taken in 

 Canadian waters in 1975 (bracketed values omitted). Mean sizes at age (series 

 combined) from Mather and Schuck (1960) for ages 1-4 (closed squares) were 

 used in fitting both curves (from Butler et al. 1977). Paints in circles represent 

 lengths of three tagged fish at ages when recaptured. 



Berry et al. (1977) did not pro- 

 vide size for age data, but they pre- 

 sented age ranges and average ages 

 for selected weight ranges of bluefin 

 tuna captured off Massachusetts in 

 1975 (Table 5). 



2. Growth of Bluefin Tuna in Its 

 First Year of Life 



There has been much interest in 

 determining the growth of the blue- 

 fin tuna during its first year of life, 

 since this information is a prerequisite 

 for validating the determinations of 

 all older ages. Data on this subject, 

 starting with the early observations 

 of d'Amico (1816) have been reca- 

 pitulated in detail by Scaccini et al. 

 (1975). The less extensive data from 

 the eastern Atlantic (Fumestin and 

 Dardignac 1 962) and the western At- 

 lantic (Rivas 1954, Mather and 

 Schuck 1960) are in good agreement 

 with those from the Mediterranean. 



The growth in weight of larval 

 and small juvenile bluefin (upto 1400 

 g, or about four months of age) 

 spawned in the central Mediterranean 

 has been described by Piccinetti and 

 Piccinetti Manfrin ( 1 970) (Figure 6). 

 These authors estimated growth by 

 assuming that the largest individuals 

 in each collection made as the season 

 progressed represented the group 

 which was hatched earliest (about 

 June 15). Thus it is possible that their 



