452 



Fishery Bulletin 89(3), 1991 



in Figure 9 for males, females, and unknown sex com- 

 bined. Length and weight-at-age, absolute growth rates 

 (AGR, cm or kg/day), and relative growth rates (RGR, 

 percent body length or weight/day) were computed for 

 the first 495 days using the appropriate growth equa- 

 tion (Table 3). The maximum AGR for blue marlin 

 (sexes combined, 1.66 cm/day) occurred at a length of 

 39 cm and an estimated age of about 50 days (Table 3). 

 The AGR then decreased continuously to about 0.09 

 cm/day at 495 days. Relative growth rates decreased 

 continuously from about 21% at 10 days to 0.04% at 

 495 days (Table 3). 



The change in length-weight relationships which 

 we detected at about 140 cm occurred later than the 

 change in form of the length-at-age relationship (about 

 110 cm). Thus, our weight-at-age curves for fish 

 > 110 cm are composites derived from lengths of mostly 

 immature fish (110- 140 cm) where no differences in 

 length-weight relationships were found, and adults 

 where sexual dimorphism was evident. As a result, they 

 show a small difference in growth rates for young 

 males and females in the length range 110-140cm, 

 even though the data in this range do not indicate 

 significant differences in either length-at-age or the 

 length-weight relationship. 



Our results show a slight decrease and then increase 

 in AGRs for weight from 80 to 150 days, but this is 

 probably an artifact of the estimation procedure. 

 Parameter estimates are very highly correlated, indi- 

 cating that growth in weight is essentially linear 

 beyond the maximum relative growth rate for weight 

 which occurs at about 70 days. 



E 

 u 



■z. 



LL) 



1 



cr 

 O 



250 



200 



100 



Gompertz (<_ 110 days) 

 P, - 115.50 

 P 2 - 7.7310 

 P 3 - 0.0392 



von Bertalanfty (>110 days) 



-54.93 



100 200 300 400 500 



TOTAL INCREMENT COUNT (days) 



Figure 9 



Length-at-age data fitted to the Gompertz equation (to the 

 left of the vertical line) for the first 100 days of life (24 larvae 

 and juvenile Atlantic blue marlin Makaira nigricans). 

 Parameters (P u P 2 , and P 3 ) are given; R 2 = 0.98. Length-at- 

 age data fitted to the von Bertalanffy equation (to the right 

 of the dashed vertical line) for the age range 110-495 days 

 (71 young adult/adult blue marlin). Parameters (P, , P 2 , and 

 P 3 ) are given; i? 2 = 0.77. 



