UCfflYAMA and STRUHSAKER: AGE AND GROWTH OF SKIPJACK AND YELLOWFIN TUNAS 



-2 



-3 



-I 



YEARS 



Figure 3. — Plot of residuals from von Bertalanffy growth curve 

 and linear growth stanzas of central Pacific skipjack tuna shown 

 in Figure 2. 



and 65 cm FL. Growth curves determined from 

 tagging data (Schaefer 1961; Joseph and Calkins 

 1969) showed slower growth. 



The sagittae of five skipjack tuna from Papua 

 New Guinea waters were examined (Figure 6). 

 These fish grew more slowly than those from the 

 central Pacific area. 



Central Pacific Yellowfin Tuna 



Two distinct stanzas of growth are evident for 

 the sample of 14 central Pacific yellowfin tuna 

 (Figure 7). Linear growth is apparent for about the 

 first 14 mo of life, after which time the data suggest 

 either the beginning of another linear growth 

 phase or an asymptotic growth process. A seg- 

 mented model with two linear phases was fitted to 

 the data (Table 3). A von Bertalanffy growth equa- 

 tion was also fitted to the data and the following 

 growth parameters were obtained: L 

 = 170.3 cm; K = 0.3864, and ^o = 0.0366 yn 

 Plots of residuals on age for both the segmental 

 model and the von Bertalanffy growth curve were 



90 



80 



70 



X 



I- 



o 



60 



50 



40 



n r 



12 



THIS STUDY (51 POINTS) 



SKILLMAN { MALES ONLY ) 



ROTHSCHILD ( UNCORRECTED) _ 



SKILLMAN ( MALES 8 FEMALES ). 



BROCK 



ROTHSCHILD ( CORRECTED ) 



Loo K 



102. Ocm 0.55 



101. 1 cm 0.39 



90.6cm 0.59 

 92.4cm _0.47 



85.5cm 0.92 



82.3cm 0.77 



'0 



-0.02yr 



18 



24 

 MONTHS 



30 



36 



Figure 4. — a comparison of von Bertalanffy growth curves determined for central Pacific skipjack tuna (for full 



references, see text). 



157 



