Short Communication Otoliths and vertebrae as potential hard structures for ageing South African yellowfin tuna Thunnus albacares

Sagittal otoliths and vertebrae from 46 yellowfin tuna Thunnus albacares (118–175 cm fork length) collected off the west coast of South Africa were assessed for potential usefulness in age estimation. Growth increments were found on both structures. Comparisons of growth increment counts showed that agreement in the counts of the number of growth increments was low (33–44%) but that most (90–94%) agreed to within one growth increment. Growth increment counts  from whole otoliths, sectioned otoliths and vertebrae were not significantly different ( t -test, p Keywords: age estimation; annuli; otoliths; precision; South Africa; vertebrae African Journal of Marine Science 2009, 31(2): 271–276