Environmental Biology of Fishes

, Volume 84, Issue 4, pp 377–391

Age and growth analysis of the shortfin mako, Isurus oxyrinchus, in the western and central North Pacific Ocean

Article

Abstract

We determined the age and growth rates of male and female shortfin makos, (Isurus oxyrinchus), from the western and central North Pacific Ocean. Growth band pairs were counted on half-cut vertebral centra using a shadowing method. In this method, we focused on the ridges on the surface of the centra, consisting of a convex and concave structure. After comparing four enhancing methods, we decided on the use of shadowing method for aging. Vertebrae from 128 males and 147 females were examined. The centrum edge analysis suggested annual band pair formation. Von Bertalanffy growth curves were fitted separately to the length-at-age data for males and females with birth length fixed. Until approximately 7 years of age, both sexes showed similar growth rates; thereafter, males showed a significantly slower growth rate compared to females. It was suggested males and females mature at approximately 6 years and 16 years, respectively. These life-history characteristics suggest relatively low productivity for this species, which agrees with reports on populations in other geographic regions.

Keywords

Shortfin mako Annual growth band pair deposition Centrum edge analysis 

Copyright information

© Springer Science+Business Media B.V. 2009

Authors and Affiliations

  1. 1.Tropical Tuna Resources DivisionNational Research Institute of Far Seas FisheriesShimizu-ward Shizuoka CityJapan
  2. 2.Project Management DivisionNational Research Institute of Far Seas FisheriesShimizu-ward Shizuoka CityJapan
  3. 3.Department of Aquatic Bioscience, Graduate School of Agricultural and Life SciencesUniversity of TokyoBunkyo-kuTokyoJapan

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