Validated age and growth of the porbeagle shark (Lamna nasus

• Main Authors: Lisa J. Natanson, Joseph J. Mello, Steven E. Campana
• Other Authors: The Pennsylvania State University CiteSeerX Archives
• Format: Text
• Language: English
• Published: 2002
• Subjects: Lamna nasus; Northwest Atlantic; Porbeagle
• Online Access: http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.490.8527; http://www.flyingsharks.eu/literature/iccat/CV054041261 - Validated age and growth POR.pdf

Growth parameters were estimated for porbeagle shark (Lamna nasus) in the northwest Atlantic Ocean on the basis of vertebral annuli. A total of 578 vertebrae was analyzed. Annuli were validated up to an age of 11 years by using vertebrae from recaptured oxytetracycline-injected and known age sharks. Males and females grew at similar rates until the size of male sexual maturity, after which the relative growth of the males declined. The growth rate of the females declined in a similar manner at the onset of maturity. Growth curves were consistent with those derived from tag/recapture analyses (GROTAG) of 76 recaptured fish, and with length-frequency methods using measurements from 13,589 individuals. Von Bertalanffy growth curve parameters (combined sexes) were: L ¥ = 289.4 cm fork length, K = 0.07 and t0 =-6.06. Maximum age, based on vertebral band pair counts, was 25 and 24 years for males and females, respectively. Longevity calculations, however, indicated a maximum age of 45 to 46 years in an unfished population. RÉSUMÉ