The utility of otolith weight in growth studies of young-of-year bony bream (Nematalosa erebi), Australia’s most widespread freshwater fish

Abstract

Otoliths are calcified structures in the inner ear of fish, the analysis of which can be used to derive important life-history characteristics. Otoliths can be used to age young fish by counting daily growth increments visible in the otolith cross-section; however, this is costly and time-consuming. Otolith weight is a potential surrogate for fish age in growth analysis, providing a rapid alternative. Bony bream (Nematalosa erebi) is Australia’s most widespread freshwater fish and an important component of riverine food webs, yet its life-history characteristics are informed by few publications. We investigated the relationship between assumed fish age derived from otolith increments and otolith weight in young-of-year bony bream. We also assessed the utility of otolith weight for use in relative growth rate analysis. Linear modelling showed a significant positive relationship between increment count and otolith weight. Otolith weight when paired with body length was a reliable alternative to increment count, and thus age, for use in relative growth studies. This method can facilitate research into the factors shaping the life history of this ecologically significant species.