Primary Study On Otolith Morphological Identification Of Coilia Mystus, Lake Anchovy (Coilia Ectenes) And Coilia Ectenes

The otolith form is species and group specific with the important value for fish taxonomy and systematics research, and some researchers have carried out the massive basic research in the field in recent years. It includes description of the otolith shape, species discrimination and stock identity.There are two kinds of methods for studying otolith shape, one is Simple otolith morphometrics, the other is Fourier shape analysis.The former studies axes of the otolith, the latter studies outline of the otolith.Otolith shape, size, smoothness degree, sulcus acusticus, rostrum and antirostrum were descirpted in detail; and some measurement characteristic including otolith length, otolith width, perimeter, area, circularity, rectangularity and compactness were analyzed,the outline of the otolith was descriped by Fourier analysis. Used these shape variables into statistical analysis to identity fish. The main findings are as follows:(1)Based on otolith position and posture in the inner ear, in order to facilitate description of the otolith, we call the direction of the head as anterior, the direction of the tail as posterior, the direction of the back as dorsal, the direction of the belly as ventral.In the meanwhile, we give the distinction of the lateral and mesial surface of otolith. Rostrum and antirostrum are created by a nick in the anterior otolith region. Otolith of Coilia mystus is egg circle with the wider posterior part, long rostrum but no antirostrum.Otolith of Coilia ectenes is also nearly egg circle with the triangle posterior part, long rostrum and short antirostrum. Otolith of lake anchovy(Coilia ectenes)is the same as Otolith of Coilia ectenes.It is also nearly egg circle with the triangle posterior part, long rostrum and short antirostrum.(2) 124 samples of Coilia mystus,297 of Coilia ectenes were collected from Lisi in May 2008 and 2009,83 of lake anchovy(Coilia ectenes)were collected from Taihu in May 2008. Three otolith measurements (length, weight and area) were significantly correlated to standard length of the fish. The growth of otolith shapes is along with the growth of the fish.(3) 124 samples of Coilia mystus and 297 of Coilia ectenes were collected from Lisi in May 2008.Using morphological variables and Fourier harmonics to describe otolith characteristic and use discriminant analyses to separate two species. The result shows that:the discriminant analysis accuracy of Coilia mystus and Coilia ectenes were 100% and 99.2%, the high accuracy of discriminant analyses show that otolith shape was described accurately by morphological variables and Fourier harmonics, discriminant analyses is an effective way to identify and separate species.(4) 137 samples of Coilia ectenes were collected from Lisi in May 2009 and 83 of lake anchovy(Coilia ectenes)were collected from Taihu in May 2008. Using morphological variables and Fourier harmonics to describe otolith characteristic and use discriminant analyses to separate two stocks. Otoliths were measured by traditional measures (otoliht length, width, diameters, area, perimeter, circularity and rectangularity), as well as by Fourier analysis to capture the finer regions of otolith. Analysis of covariance (ANCOVA) showed that there was significant correlation between morphological variables (diameter, otolith length, otolith width, otolith area, harmonics5,harmonics6, harmonics7, harmonics10, harmonics12, harmonics14, harmonics18, harmonics19, and harmonics20) and body length. To minimize size effects on the shape variables between species only fish of a medium to all length (180-240mm) were included in the data analysis and the variables which has significant relation with body length were transformed using residual.The result shows that:the discriminant analysis accuracy of Coilia ectenes and lake anchovy (Coilia ectenes)were 98.5% and 98.8%, the high accuracy of discriminant analyses show that otolith shape was described accurately by morphological variables and Fourier harmonics, discriminant analyses is an effective way to identify stocks.(5) 124 samples of Coilia mystus,297 of Coilia ectenes were collected from Lisi in May 2008 and 2009,83 of lake anchovy(Coilia ectenes)were collected from Taihu in May 2008.Using morphological variables and Fourier harmonics to describe otolith characteristic and use discriminant analyses to separate them.The result shows that:the discriminant analysis accuracy of Coilia mystus, Coilia ectenes and lake anchovy(Coilia ectenes)were 96.0%,92.9% and 92.8%. The high accuracy of discriminant analyses show that otolith shape was described accurately by morphological variables and Fourier harmonics, discriminant analyses is an effective way to identify Coilia mystus, Coilia ectenes and lake anchovy(Coilia ectenes)...