Radiometric age validation of the yelloweye rockfish (Sebastes ruberrimus) from southeastern Alaska
Allen H. Andrews, Gregor M. Cailliet, Kenneth H. Coale, Kristen M. Munk, Melissa M. Mahoney and Victoria M. O'Connell
Marine and Freshwater Research 53(2) 139 - 146
Abstract
The yelloweye rockfish (Sebastes ruberrimus), a dominant
component of an important deep-water rockfish fishery of the Gulf of Alaska,
is thought to be long-lived with an estimated longevity exceeding 100 years.
For the purpose of monitoring stocks, age is routinely estimated by counting
growth zones in otolith cross-sections using the break-and-burn technique;
however, such age estimates for this species have remained unvalidated. To
evaluate these age data, age estimations from the break-and-burn technique
were corroborated by comparing results from transverse sectioning of otoliths.
The agreement between the techniques was excellent and each technique had a
very low coefficient of variation (3.6% and 4.5%). Radiometric
age validation of these estimates was performed on the otolith core material
(first three years of growth) of pooled age groups having an average estimated
age of 27.4–101.4 years. Agreement was variable and somewhat subjective,
but radiometric data support ages estimated from otolith growth zone counts.
The strongest support for age that exceeds 100 years comes from the
observation that as age derived from growth zones approached and exceeded 100
years, the sample ratios measured
(210Pb:226Ra) approached
equilibrium. The radiometric results of our study validate the estimates
derived from growth zones and the age estimating procedures, which confirms
that the longevity of yelloweye rockfish exceeds 100 years.
Full text doi:10.1071/MF01126
© CSIRO 2002





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