FISHERY BULLETIN: VOL. 79, NO, 2 



in 



CM 



CO 



120 



I.CX) 



.80 



.60 



.20 



o GROUP A, Y'.ZSIA 

 * GROUP B+C, 9=.I85A 



125 



250 



375 



500 



625 750 



DAYS OUT 



875 



1000 



1125 



1250 



1375 



1500 



YEARS OUT (A) 



Figure 2. — Regression of growth variable, Y, on years between release and recapture for albacore of Groups A (221 fish) and B + C 

 (189 fish). The slopes are estimates of the von Bertalanffy growth parameter, K, and they are significantly different. 



Table 3. — Estimates of von Bertalanffy growth parameters for North Pacific albacore by 

 recapture group and estimation method, assuming stock boundary at lat. 40° N. 



Hawaiian longline fishery, which harvests the 

 largest North Pacific albacore known, specimens 

 >125 cm are extremely rare. With L^ fixed at 125 

 cm. Group A had the highest growth rate esti- 

 mate, Ka = 0.231/yr (Table 3). Group B and 

 i^B = 0.193, and Group C had the lowest growth 

 rate estimate, itc = 0.184. When Groups B and C 

 were pooled into a "North" category, the result- 

 ing /t^ was 0.185. The estimate of K for all three 

 groups combined was 0.199. 



Table 3 also shows the statistics on average 

 time between release and recapture. Group A fish 

 were at liberty an average of 313 d, while Group 

 B fish were out 400 d, and Group C fish, 588 d. 



Tagged fish from Groups B and C combined were 

 at large an average of 513 d. 



The estimates suggest that the North fish. 

 Groups B and C, had a lower growth rate than the 

 South fish of Group A. Such a difference might 

 arise if, as we suppose, the North fish budget more 

 of their available energy for migration compared 

 with the South fish, and relatively less energy for 

 growth. Tag release and recovery results indicate 

 that the North fish make longer migrations, 

 traveling between coastal waters off the United 

 States Pacific Northwest and coastal waters off 

 Japan, while the South fish undertake shorter 

 migrations between coastal waters south of Cape 



298 



