Lead]radium dating provides a framework for coordinating age estimation of Patagonian toothfish (Dissostichus eleginoides) between fishing areas

Patagonian toothfish (Dissostichus eleginoides) or "Chilean sea bass" support a valuable and controversial fishery, yet its life history is not well understood and longevity estimates range from approximately 20 to more than 40 or 50 yr.  In this study, lead-radium dating provided valid ages for juvenile to older adult groups ranging up to approximately 30 years and results were consistent with the counting of otolith growth zones in transverse sections as accurate indicators of age.  Lead-radium dating revealed minor biases in the age interpretation of otolith growth zone counting between regional fishing areas monitored by two different facilities, Center for Quantitative Fisheries Ecology (CQFE) and the Central Ageing Facility (CAF).  For CQFE, an under-ageing bias of ca. 3.3 years was the observed trend across estimated ages younger than 20 years. For the CAF, bias was overestimated age for young fish and underestimated age for the oldest fish. These findings provide: 1) an opportunity for the CCAMLR Otolith Network to reassess otolith interpretation and growth modeling using age-validated information; 2) independent age estimates that are consistent with longevity estimates from other studies that exceed 20 years; and (3) more generally illustrate the potential problem with confounding differences between laboratory readings for geographically separated fish populations with demonstrated population connectivity.

Manuscript published: Marine and Freshwater Research (Vol 62, 2011).

This is one of two papers that resulted from my Ph.D in Ichthyology and Fisheries Science through Rhodes University.

Dissertation:

AHAndrews-2009-PhD-RhodesUniversity.pdf

Recommended reading: Hooked: Pirates, Poaching and the Perfect Fish by Bruce Knecht.

This book provides an excellent account of how the Chilean sea bass market started, while running in parallel with a hot pursuit of a pirate ship across the Southern Ocean.  A riveting read.