HILL ET AL.: ANALYSIS OF GROWTH ZONES IN PACIFIC BLUE MARLIN 



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200 



100 



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Males 



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 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 



Females 



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300 



5 200 



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2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 



Anal Spine Band Count 



Figure 11. — Mean LJFL at age for male and female Pacific Makaira nigricans based on 

 anal spine corrected band counts. Vertical lines terminated by narrow horizontal lines 

 represent 959c confidence intervals (male n = 149; female n = 48). Closed diamond indicates 

 estimated age of largest female sampled (748 kg) based upon dorsal spine and sagitta 

 counts. 



sagittal growth patterns is more subjective com- 

 pared with the interpretation of spines. 



Based on preliminary age estimates in this 

 study, Pacific blue marlin males have a longevity 

 of at least 18 years and females of at least 27 

 years of age. The largest female reported in this 

 study was estimated to be 22 years of age based 

 upon both dorsal spine and sagitta counts. The 

 largest male sampled in this study (170.3 kg) was 

 estimatd to be only 14 years of age and the oldest 

 male (estimated age 18) was just above mean 

 size. Wilson's (1984) study of Pacific blue marlin 

 provided similar age estimates and sizes for each 

 sex. 



CONCLUSION 



1) Anal fin spines, dorsal fin spines, and sagit- 

 tal otoHths contained gi-owth information which 

 we assumed to be annual in nature and to hold 

 promise for age estimation of this species. Incre- 

 mental patterns in caudal vertebrae, possibly 

 related to some other envu'onmental or gi'owth 

 stimuli, were not useful for age estimation at this 

 time. 



2) Anal and dorsal fin spines are simpler to 

 collect and process than sagittae, and to provide 

 more precise (although not necessarily more ac- 

 curate) age estimates for this species. The prob- 



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