Application of image chain code in otolith shape analysis in two closely related species of family Lutjanidae

Document Type : Biology(Animal)

Authors

1 Iranian Fisheries Research Organization, Tehran, Iran

2 Islamic Azad University Science and Research Branch, Iran

3 Iran Fisheries Research Institute, Iran

Abstract

Otolith contour from two species of family Lutjanidae, Lutjanus malabaricus and Lutjanus johnii from Persian Gulf and Oman Sea were investigated for species separation. For that, 20 samples from each species in the first stage and 39 and 41 samples for L.malabaricus and L. johnii in the second stage were used, respectively.  The image of extracted otoliths were taken, digitized and then analyzed using Shape Programm and Elliptic Fourier Analysis. For each sample, chain code, harmonic and elliptic Fourier coefficients were generated and medium otolith contour reconstructed by combination of these harmonics. The results showed that the number of samples is very important in species separation and with low number of otoliths it is not possible to separate species using this method. Therefore with choosing appropriate number of samples, it is possible to reconstruct the otolith contour for each species and detect the differences between two closely related species based on otolith morphology. This investigation is an effort to explain some benefits of elliptic Fourier harmonics in otolith morphology.   

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