MORPHOLOGICAL, BEHAVIOURAL, AND ENERGETIC MECHANISMS OF CANNIBALISM IN JUVENILE BARRAMUNDI (Lates calcarifer): A LITERATURE SYNTHESIS WITH FIELD-BASED HATCHERY PERSPECTIVE

Abstract

Cannibalism is a major constraint in juvenile barramundi (Lates calcarifer) hatchery production, particularly during the nursery phase when size heterogeneity, feeding competition, and predator–prey encounters increase. This article synthesizes published evidence and field-based hatchery perspectives to explain the morphological, behavioural, and energetic mechanisms underlying cannibalism and their implications for hatchery management. The synthesis focused on four domains: morphological limitation, prey-size vulnerability, energetic profitability, and nursery management factors, including grading, stocking density, and feeding frequency. The findings indicate that cannibalism is initiated mainly by size heterogeneity, where smaller juveniles become vulnerable when their body size allows capture and ingestion by larger conspecifics. Morphological constraints determine the physical feasibility of ingestion, whereas capture success, escape response, and handling time influence prey vulnerability. Energetic evidence further explains cannibalism persistence because cannibalistic individuals may gain growth advantages that intensify cohort size disparity. Therefore, cannibalism control should integrate early size monitoring, preventive grading, shooter removal, density regulation, and increased feeding frequency. This synthesis provides a practical framework for improving juvenile survival and nursery efficiency in tropical barramundi hatcheries.