Taxonomic studies on the 0-group eel larvae (Anguilla sp.) caught in the Sargasso Sea in 1979

Abstract

More than 2000 0-group larvae (5.0-30.0 mm long) of both Atlantic Anguilla species were examined taxonomically. With regard to the total number of myomeres in A. rostrata and A. anguilla, an average difference between the two species of 6 to 8 myomeres was found in all size groups. 31 specimens (i.e. 1.76 %) exhibited 111 myomeres. The position of the last vertical blood vessel and the number of preanal myomeres turned out to be statistically different in both species; however, these differences cannot be used for species identification. The regression line for the position of the last vertical blood vessel according to the total number of myomeres indicates that individuals with a total of 111 myomeres may be A. anguilla. Measurements of total lengths revealed highly significant differences between the larvae of both eel species. It can be concluded that, on the average, A. rostrata ( {Mathematical expression}) hatched about two weeks before A anguilla ( {Mathematical expression}). On the other hand, results obtained from the biggest A. rostrata larvae (29.5 mm) and A. anguilla larvae (23.5 mm) make a spawning of A. rostrata likely two months before A. anguilla, when findings from hatching experiments with A. japonica are taken as a basis. There is no difference in the relative length of the intestine in either Anguilla species. © 1982 Biologische Anstalt Helgoland.