Field-based body condition scoring system for dugongs (Dugong dugon): development using morphometric indices and blubber thickness

The dugong (Dugong dugon) is a protected marine mammal in Thailand, yet body condition score (BCS) assessments remain subjective and lack standardized benchmarks. This study aimed to identify key morphometric and blubber predictors of body condition score (BCS) in dugongs to develop a standardized, field-based assessment framework. To achieve this, necropsy records of 82 stranded dugongs from the Andaman Sea (2019–2025) were analyzed, summarizing morphometric and blubber data across age classes and BCS levels. Univariable and penalized ordinal logistic regression identified predictors associated with BCS, which were combined with descriptive statistics to construct heuristic thresholds. Although predictors of BCS differed across age classes, their common ground highlighted parameters that were most consistent across stages. For field application, average blubber thickness, body weight, and body condition index (BCI) were therefore selected as the robust predictors for developing heuristic thresholds. These were consolidated into BCS charts and lookup tables, providing practical morphometric cutoffs for necropsy and stranding investigations. This study represents the first attempt to establish field-based BCS assessment tools for dugongs, improving objectivity and consistency in condition evaluation. While not intended as definitive diagnostics, the thresholds enhance comparability across cases, with extreme categories (BCS 1 and 5) still requiring expert confirmation and further validation through larger sample sizes and longitudinal studies.