Assessing interspecific variation in life-history traits of three sympatric tropical mullets using age, growth and otolith allometry

Life history theory predicts that organisms optimize their life-history traits according to evolutionary context and environmental constraints. Sympatric estuarine-dependent fish are intriguing subjects for studying life-history variation, as their traits are molded by their complex habitat use and co-occurrence with ecologically similar species. In this study, we investigated life-history traits of three tropical mullet species (Mugil curema, M. liza and M. rubrioculus) using age, growth, and otolith allometry. Our results indicate that otolith allometric patterns are useful predictors of specific life history traits: the faster-growing species M. rubrioculus (K = 0.31) was characterized by earlier stanza changing points (SCPs), with 0.8 years of life. In contrast, the slower-growing species, M. liza (K = 0.21) was characterized by later changing points, 1.3 years of life. M. curema is intermediate (K = 0.25), with 0.95 years of life. The first SCP may register juvenile movements between estuarine and coastal habitats before the first year of life, and the second SCPs appear to reflect the migration to the sea and age at maturation. More generally, our study species exhibit fine-scale temporal differences in life cycle events that may be related to growth rates and body size that can be predicted by otolith allometry, as well as a gradient of interspecific divergences in life-history traits. These are likely to be driven by differences in their migratory behavior and habitat use that permit coexistence.