Disregarding fish ageing method can compromise growth parameter comparability across studies

Abstract

Reliable and comparable growth estimates are critical for accurate comparative studies, robust stock assessments, and effective fisheries management. Many studies compare fish growth Von Bertalanffy parameters (growth coefficient K and asymptotic length L{infty}) across species, populations, or time periods. These parameters are often obtained from literature or FishBase without accounting for ageing method used to estimate size-at-age, despite known differences in age estimates from different structures. In this study, we use four species as a case study and once again demonstrate that fish ageing based on otoliths and scales can produce significantly different estimates of L{infty} and K. We then analyse available K and L{infty} records from FishBase and show that L{infty} values derived from scales were, on average, 15% higher than those obtained from otoliths, while K values were 20% smaller (p < 0.01 in both cases). We strongly recommend that ageing methods be clearly reported in all growth studies and included in databases, that comparative analyses explicitly account for ageing method in statistical model structure, and that researchers consider methodological differences when interpreting growth parameter variations across studies.