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Fishery Bulletin 101(3) 



Longevity estimates for the blue shark indicate that 

 they may Hve for 26 years when Taylor's ( 1958) method is 

 employed. On the other hand, Fabens" (1965) method for 

 >99% longevity produced an estimate of 20.7 years, which 

 may be more realistic. The maximum age determined from 

 vertebral band-pair counts was 16 and 15 years for males 

 and females, respectively. An analysis of maximum times at 

 liberty for tagged blue sharks supports the notion that this 

 species does not live as long as previously reported for the 

 North Atlantic. Of the 4967 blue sharks recaptured to date. 



99% were at liberty for less than five years. The maximum 

 times at liberty are 9.1 and 8.5 years, despite the 39-year 

 history of the tagging program. The shark at liberty for 9.1 

 years was a male tagged at an estimated 122 cm FL; size at 

 recapture was not reported. According to our growth curve, 

 the shark was tagged at 1* years of age, which would cor- 

 respond to a maximum age of 10+ years at recapture. The 

 shark at liberty for 8.5 years, also a male, was estimated 

 to be 198 cm FL at tagging, which would correspond to 5* 

 years of age. Therefore, at recapture, this fish would be a 

 maximum age of 13.5 years, although its measured 

 FL at recapture actually corresponds to 11 years 

 on our growth curve. The largest long-term recap- 

 ture was a male, 244 cm FL at tagging and 266 

 cm FL at recapture 6 years later. This would cor- 

 respond to an estimated age of 10 years at tagging 

 and 16 years at recapture, which falls well within 

 the values of directly aged vertebrae (Fig. 5). 



The occurrence of sexual differences in growth 

 is well documented in elasmobranchs; females 

 usually grow larger than males (Cortes, 2000). 

 Although the largest blue shark in our study was 

 a 312-cm-FL female, there is little evidence that 

 large females are highly abundant in the North At- 

 lantic. Maximum size male and female specimens 

 in our study, 284 cm FL and 312 cm FL, respective- 

 ly, represented the largest reliably measured blue 

 sharks from the North Atlantic, with the exception 

 of a 320-cm-FL specimen (sex unspecified) exam- 

 ined by Bigelow and Schroeder (1953). Indeed, 

 a thorough review of the literature reveals that 

 although 288-cm-FL and 279-cm-FL females were 

 reported by Gubanov and Grigoryev (1975) from 

 the Indian Ocean, males are consistently cited as 

 being very much larger than females in the world's 



