ABSTRACT
Sectioning otoliths and counting opaque bands (one complete annular increment is defined as an opaque and a translucent band) is an accepted protocol for determining the age of Red Snapper, Lutjanus campechanus. The number of opaque (annular) bands on whole otoliths (whole age) was compared with the number of opaque bands on sectioned otoliths (section age) to investigate the accuracy and utility of age determination from whole otoliths. A stratified random sample (N = 601) was taken from collected fish (N = 1758) for comparison of whole with section ages. Most (79%) of the whole ages were the same as section ages. There was a significant correlation between whole and section ages (r = 0.95), but the slope was less than one (b = 0.89). Mean differences between whole and section ages by size interval indicated that estimated ages of fish greater than 600 mm standard length (SL) were underestimated by whole ages. Therefore, a combined age protocol was developed with section ages 186for fish greater than 600 mm SL and whole ages for fish less than 601 mm SL. In support of this protocol, for fish less than 601 mm SL, there was a significant correlation between section and whole ages (r = 0.96), and the slope was 0.999. A comparison of von Bertalanffy growth rates derived from section and from whole-section ages showed that they were not significantly different and were similar to previous growth rate estimates. The present study provided an accurate ageing protocol of counting opaque bands on whole otoliths in Red Snapper for fish less than 601 mm SL, which has the potential to increase efficiency and reduce laboratory preparation costs. However, counting opaque bands on whole otoliths required more training and experience compared with determining age from sectioned otoliths; thus, examining whole otoliths for age determination in Red Snapper may not be effective if laboratory personnel frequently change.
