Sclerochronological age synchrony corroborates remarkable lifespan and protracted asymptotic growth for a deepwater snapper (Pristipomoides zonatus) in the Indian and Pacific Oceans

Abstract

Although Pristipomoides zonatus (oblique banded snapper) constitutes an important fisheries resource throughout its broad geographic distribution across the Indo-Pacific region, life history information remains poorly understood, particularly throughout the southern hemisphere. This study used nascent otolith preparation methods to produce very thin transverse sections (∼150 µm) that improved the accuracy and precision of age estimates. The use of sclerochronological crossdating determined that opaque zones were deposited annually in otoliths and were synchronous with time-specific environmental climate records (i.e., the Leeuwin Current) over nearly four decades (1969–2007). These chronologies also exhibited a strong inter-series correlation that indicated clear and synchronous growth among all individuals (expressed population signal, EPS = 0.728). The growth of this species differed significantly between sexes and oceans, with each sex reaching a greater length-at-age in the Pacific Ocean compared to the Indian Ocean, and males attained a greater length-at-age than females within each ocean. All growth trajectories exhibited a very protracted asymptote of up to five decades with exceptional longevities recorded for both oceanic regions to a maximum age of 60 years. The results of this study indicated that stock assessments of P. zonatus would benefit from an explicit understanding of the regional biology and the use of sex-specific growth curves for more reliable biomass estimates.