Otoliths, or ear-stones, are calcareous components in the static-acoustic organs of teleost fishes with a characteristic morphology. As such, they are widely used in fisheries because of the information stored in them concerning, for example, environment, age, and so forth. Otoliths of three lethrinid species Lethrinus borbonicus (Valenciennes, 1830), L. lentjan (Lacepède, 1802), and L. mahsena (Forsskål, 1775) were collected from fish caught along the Red Sea coast of Yemen. Images taken with a scanning electron microscope were used to determine their characteristics. Twenty-two characters were defined to describe the shapes of the otoliths. Eleven measurements of distance between selected features were used for a linear regression and multivariate analysis to characterize the species by their otoliths. The results illustrate ontogenetic changes for different age groups based on the recorded shapes. All three species show a linear relationship between the total length and the morphometric measurements. A linear discriminant analysis shows marked differences between the otoliths of the three species and emphasizes the importance of the measured variables. Otoliths of L. lentjan and L. borbinicus are more similar to each other and differ from those of L. mahsena. A comparison with previously published otoliths of the species studied from other areas confirms an intraspecific uniformity across larger geographic distances, making the characters useful for diagnostic purposes. |
