A Spatial and Geophysical Exploration of Atlantic Eel Larval Distributions

Abstract

In the context of declining populations of freshwater eels in Europe and North America and inspired by observations of Japanese eel spawning near seamounts, this study explored a possible spatial relationship between spawning American and European eels (Anguilla rostrata and A. anguilla) and geophysical features in the Sargasso Sea. A spatial analysis of positive and null catch sampling data from 1863 to 2007 found observations of young eel larvae significantly clustered over magnetic anomalies with higher than average intensities. These larval clusters occurred above the southwest Bermuda Rise and in the vicinity of the Vema Gap, a constricted abyssal channel connecting the Nares and Hatteras Abyssal Plains and directing flow of the abyssal bottom current. In this area, newly hatched larvae were positioned on either side, but not within, a 170 km wide high-magnetic gradient band located on the M0 anomaly. This gradient separated the centers of the distributions of the two species when they were ≤ 5 mm in length. Standard deviations of directional trends indicated probabilities in dispersal patterns, highlighting a potential tool for modeling larval distributions. Like other species undergoing oceanic migrations, eels have demonstrated a magnetic sensory ability and may rely on magnetic cues for navigation. The geomagnetism of the ocean floor, which attenuates at a cubic rate with distance, may provide a clue to eel migratory routes and depth preferences or play a role in larval dispersal, metamorphosis and recruitment. Spatial analyses open new opportunities to study anguillid distributions in relation to geomagnetic and oceanographic features.