Age estimation and lead-radium dating of golden tilefish, Lopholatilus chamaeleonticeps

Abstract

There is a growing concern over the lack of life history information for many deepwater fisheries species, including golden tilefish, Lopholatilus chamaeleonticeps. Fundamental life history characteristics, like age and growth, are required for effective, age-structured stock assessments and management decisions. A previous effort to validate golden tilefish age estimates using bomb radiocarbon dating was inconclusive, which led to an application of lead-radium dating in the current study. Lead-radium dating uses the radioactive disequilibrium of lead-210 (210Pb) and radium-226 (226Ra) in otoliths as an independent estimate of age. Ages were also estimated using traditional age estimates by counting growth zones in thin otolith sections and lead-radium dating was used to test these estimates. Radiometric ages (corrected for time since capture) were similar to age estimates from growth zone counts for two of the female age groups and the two oldest age groups of unknown sex, which confirmed an annual growth zone deposition. However, radiometric ages did not agree with age estimates from growth zone counts for males. The difference may be attributed to geographical variations in radium levels, growth rates and growth zone formation by gender or gender transition. Male sagittal otoliths revealed inconsistent growth zone patterns in thin sections, which may have contributed to underageing. Golden tilefish longevity was confirmed to 26 years.