Entry of migrating American eel leptocephali into the Gulf Stream system

Abundance, size and depth distributions of American eel(Anguilla rostrata) leptocephali collected in four transects across the Florida Current between the Straits of Florida and Cape Hatteras, North Carolina, were examined in order to assess the relative importance of two migration routes into the Gulf Stream system. A nine-fold increase in the abundance and an increase in the mean length of leptocephali collected in the Florida Current north of the Straits of Florida indicate that most leptocephali enter the Gulf Stream system directly from the Sargasso Sea rather than by a more southern route through the Bahama Islands. Leptocephali were concentrated in the upper 140 m at night and upper 350 m during the day. Wide vertical ranges in daytime collections precluded more refined estimation of vertical distribution. The collection of eight small leptocephali (11 to 17 mm total length) in the western Caribbean Sea is discussed in relation to the origin of leptocephali taken in the Straits of Florida.