Identification of larval stages of fish in southeastern coastal waters of the Caspian Sea- Golestan Province

Abstract

This study was carried out to develop a practical guide for identifying species of fish larvae in coastal waters of Caspian Sea-Golestan Province. A total of 18 sample sites in the Caspian Sea and 6 sampling sites in the Gorgan Bay was sampled monthly from March to September 2015 with a Bongo net (diameter, 46cm; mesh size, 330 µm). Most of the fish larvae belonged to postflexion and transitional stages. Morphological and meristic measurements were made. Fish larvae included Atherina boyeri, Rutilus rutilus, Rutilus firisii kutum, Cyprinus carpio, Liza saliens, Liza aurata and Gambusia holbrooki, representing 5 genera in 4 families. Results showed Cyprinus sp. and Rutilus sp. separated based on pigments patterns on the body while R. rutilus and R. frisii kutum were discerned by the number of pre-anal myomers. Liza spp. could be differentiated by different pigments patterns and some morphometric characters including eye diameter, body depth, and head length. The results of this study revealed that in contrast to the current perception, the analysis of the morphometric variation of Liza sp., Rutilus sp., and Cyprinus carpio fry could be used for their discrimination.