Differentiation of Lesueurigobius sanzi and L. suerii through otolith morphometric analysis

Otolith morphology is a valuable tool for species identification, particularly for morphologically similar species. This study evaluates the potential of otolith morphometry to distinguish Lesueurigobius sanzi and L. suerii , two closely related species commonly found as fishery discards in the Gulf of Cádiz. A total of 1,019 individuals ( L. sanzi : 921, L. suerii : 98) were collected and their otoliths were analysed using the R package "shapeR" to obtain morphometric parameters and standardised wavelet coefficients. Statistical analyses revealed significant morphological differences between the species. Principal Component Analysis (PCA) showed that otolith length, perimeter, and shape indices contribute significantly to species differentiation. Furthermore, a Linear Discriminant Analysis (LDA) based on standardised wavelet coefficients demonstrated high classification accuracy (91.6%), confirming the effectiveness of this approach for species identification. These findings highlight the reliability of otolith morphometry as a robust method for distinguishing L. sanzi and L. suerii , providing valuable insights for fisheries management and biodiversity studies. This research contributes to the development of classification methods, essential for sustainable fishery assessments and ecological research. • Otolith morphometry allows reliable differentiation between Lesueurigobius sanzi and L. suerii. • Wavelet-based descriptors achieve the highest classification accuracy (91.6%), representing the most effective method for these species identification. • Circularity, form factor, and aspect ratio emerge as the most informative shape indices, reflecting differences in otolith elongation and compactness. • Otolith analysis proves to be a cost-efficient and powerful tool to improve species identification in discards, supporting more accurate fisheries management and conservation strategies.