Morphological Variations in the shapes of the otolith in the freshwater sardine Sardinella tawilis and marine sardine Sardinella lemuru using Elliptic Fourier Analysis

Elliptic Fourier analysis (EFA) was used to discriminate otolith shapes between the two species of Sardinella. The freshwater sardine Sardinella tawilis from Taal lake, and the marine sardine Sardinella lemuru from Butuan bay were investigated to find out whether these two species varied in their otoliths considering the fact that they were from two different aquatic environments. Principal component (PC) scores were obtained from EFA of the left, right, and both otoliths using SHAPE ver1.3 software. Discriminant Function Analysis of PC scores was used to determine the frequency of correctly classified fishes that showed 99.31% correct classification indicating a high discrimination between the two species. While otolith shapes were shown to be highly conserved among the sexes within the species, main variations between the two species were prominent in the dorsal, anterior (i.e. in the antirostrum, excisura, and rostrum) and in the ventral side below the rostrum. This study clearly showed that the shape variations can be quantitatively described using EFA.

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