IDENTIFICATION OF VENDACE (COREGONUS-ALBULA (L)) AND WHITEFISH (COREGONUS-LAVARETUS) LARVAE BY THE COUNTS OF MYOMERES

In this study on vendace (Coregonus albula (L.)) and whitefish (Coregonus lavaretus L.s.l.) larvae collected from Lake Pyhajarvi (SW Finland), Lake Puruvesi, Lake Paasivesi and Lake Pyhaselka, myomere counting was tested as a method for the identification of these two species. Distributions of pre-anal myomere counts indicated significant differences between species in all lakes and proved adequate for the separation of vendace and whitefish larvae. Vendace larvae usually had 37-39 pre-anal myomeres, while the larvae with myomere counts greater than 40 were whitefish. In Lake Pyhajarvi, the mean pre-anal myomere counts of vendace differed significantly between years, but this variation did not hamper the identification of the larvae. There were no differences in post-anal myomere counts between species. Within each lake there was no significant correlation between the myomere count and the total larval length in either species.