TY - JOUR T1 - Analysis of bomb radiocarbon data for common thresher sharks, Alopias vulpinus, in the northwestern Atlantic Ocean with revised growth curves JF - ENVIRONMENTAL BIOLOGY OF FISHES Y1 - 2015 A1 - Natanson, Lisa J. A1 - Hamady, Li Ling A1 - Gervelis, Brian J. KW - Age KW - Carbon-14 KW - Centra KW - Elasmobranchs KW - Vertebral column AB - Bomb radiocarbon dating was used to determine the periodicity of band pair formation in the vertebral centra of three common thresher sharks (Alopias vulpinus). The traditional interpretation of band pairs were accurate (i.e. annual) up to approximately 14 years of age. In older individuals, band pair counts underestimated age. A new maximum validated age was estimated to be 38 years (an increase of 18 years over the band count estimates). Previously reported length at age estimates for common thresher sharks up to 14 years were used in conjunction with the two older validated estimates to develop a revised growth curve for the species, which was described using the Schnute general model (sexes combined). Updated estimates of age at maturity remained the same for males (8 years) and increased by one year to 13 years for females. The primary finding was the increase in longevity for this species from a band pair count estimate of 24 years to a bomb radiocarbon validated estimate of 38 years, indicating this species lives much longer than previously thought. VL - 99 ER - TY - JOUR T1 - Validated age and growth estimates for Carcharhinus obscurus in the northwestern Atlantic Ocean, with pre- and post management growth comparisons JF - Environmental Biology of Fishes Y1 - 2014 A1 - Natanson, Lisa J. A1 - Gervelis, Brian J. A1 - Winton, Megan V. A1 - Hamady, Li Ling A1 - Gulak, Simon J. B. A1 - Carlson, John K. KW - Age and growth KW - bomb radiocarbon KW - Dusky shark KW - Elasmobranch KW - Validation KW - Vertebrae AB - Age and growth estimates for the dusky shark, Carcharhinus obscurus, were derived from vertebral centra collected in the northwestern Atlantic Ocean. Sample collection spanned the years prior to and following the implementation ofmanagementmeasures (1963– 2010). Growth was compared pre- and post- population depletion and pre- and post- management to investigate the possibility of density-mediated shifts in age and growth parameters over time. There was no evidence of difference between periods for either sex. Additionally, bomb radiocarbon dating was used to determine the periodicity of band pair formation. Results support the traditional interpretation of annual band pairs up to approximately 11 years of age. After this time, vertebral counts considerably underestimate true age. Maximum validated ages were estimated to be between 38 and 42 years of age (an increase of 15 to 19 years over the band count estimates), confirming longevity to at least 42 years of age. Growth curves estimated using only validated data were compared to those generated using band pair counts. Logistic growth parameters derived from validated vertebral length-at-age data were L∞=261.5 cm FL, Lo=85.5 cm, to=4.89 year and g=0.15 year−1 for the sexes combined. Revised estimates of age at maturity were 17.4 years for males and 17.6 years for females. VL - 97109251443124592565546445894545835645277154931266199319909310036110823842426199561196662521049 UR - http://link.springer.com/10.1007/s10641-013-0189-4http://link.springer.com/content/pdf/10.1007/s10641-013-0189-4 IS - 8C34212 ER -