Validated age and growth estimates for Carcharhinus obscurus in the northwestern Atlantic Ocean, with pre- and post management growth comparisons

• Published in: Environmental biology of fishes Vol. 97; no. 8; pp. 881 - 896
• Main Authors: Natanson, Lisa J, Gervelis, Brian J, Winton, Megan V, Hamady, Li Ling, Gulak, Simon J. B, Carlson, John K
• Format: Journal Article
• Language: English
• Published: Dordrecht Springer-Verlag 01.08.2014; Springer Netherlands; Springer; Springer Nature B.V
• Subjects: Agnatha. Pisces; Animal and plant ecology; Animal Systematics/Taxonomy/Biogeography; Animal, plant and microbial ecology; Animals; Autoecology; Biological and medical sciences; Biomedical and Life Sciences; Carcharhinus; Carcharhinus obscurus; Environment; females; Freshwater & Marine Ecology; Fundamental and applied biological sciences. Psychology; Life Sciences; longevity; males; Marine; Marine biology; Nature Conservation; periodicity; Physical growth; Radiocarbon dating; Sea water ecosystems; Sharks; Synecology; Vertebrata; Vertebrates: general zoology, morphology, phylogeny, systematics, cytogenetics, geographical distribution; Zoology; Atlantic Ocean; ANW, Atlantic; Validation; Vertebrae; Dusky shark; Age and growth; Elasmobranch; Bomb radiocarbon; Growth; Marine environment; Vertebrata; Pisces; Nuclear explosion; Chondrichthyes; Age
• DOI: 10.1007/s10641-013-0189-4
• ISSN: 0378-1909

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 of management measures (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, L ₒ = 85.5 cm, t ₒ = 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.