MORPHOMETRIC RELATIONSHIPS BETWEEN SAGITTAL OTOLITH SHAPE AND BODY SIZE IN FIVE MARINE FISH SPECIES FROM LANG CO - HAI VAN, VIETNAM

This study examines the relationship between sagittal otolith morphology and body size in five common marine fish species-Selaroides leptolepis, Sardinella gibbosa, Gerres filamentosus, Lutjanus russellii, and Selar crumenophthalmus-from the Lang Co - Hai Van coastal area of Vietnam. A total of 210 specimens were analyzed using Basic Dimension Parameters (BDPs: otolith length, width, area, and perimeter), Shape Indices (ShIs), and somatic traits (total length and body weight). MANOVA and Linear Discriminant Analysis (LDA) results revealed significant interspecific differences in otolith shape, with high classification accuracy (84.78-100%) and perfect discrimination for Lutjanus russellii. Regression analyses demonstrated strong linear correlations between otolith dimensions and body size, especially with otolith height and area (R² up to 0.962). Additionally, length-weight relationships (LWRs) showed species-specific allometric growth patterns: positive allometry in Gerres filamentosus and Selaroides leptolepis, and negative allometry in Lutjanus russellii, Sardinella gibbosa, and Selar crumenophthalmus, suggesting ecological and physiological variability across taxa. These findings support the use of otolith morphometrics for species identification and fish size estimation, with practical applications in fisheries biology, dietary analysis, and historical ecology.