Direct observations of American eels migrating across the continental shelf to the Sargasso Sea.

Mélanie Béguer-Pon,Julian J. Dodson,José Benchetrit,Martin Castonguay,Shiliang Shan

doi:10.1038/ncomms9705

Mélanie Béguer-Pon, Julian J. Dodson + Show 3 more

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https://doi.org/10.1038/ncomms9705

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Abstract

Since inferring spawning areas from larval distributions in the Sargasso Sea a century ago, the oceanic migration of adult American eels has remained a mystery. No adult eel has ever been observed migrating in the open ocean or in the spawning area. Here, we track movements of maturing eels equipped with pop-up satellite archival tags from the Scotian Shelf (Canada) into the open ocean, with one individual migrating 2,400 km to the northern limit of the spawning site in the Sargasso Sea. The reconstructed routes suggest a migration in two phases: one over the continental shelf and along its edge in shallow waters; the second in deeper waters straight south towards the spawning area. This study is the first direct evidence of adult Anguilla migrating to the Sargasso Sea and represents an important step forward in the understanding of routes and migratory cues.

Highlights

Since inferring spawning areas from larval distributions in the Sargasso Sea a century ago, the oceanic migration of adult American eels has remained a mystery
Of the 38 pop-up satellite archival tags (PSATs) attached to eels and released on the Scotian Shelf over 3 years, 28 successfully transmitted their data after popping off at an estimated distance of 5–1,570 km from their release site (Fig. 1 and Supplementary Table 1)
This study represents an important step forward in the understanding of the oceanic migration of anguillid eels and the possible orientation mechanisms used by the species

Summary

Introduction

Since inferring spawning areas from larval distributions in the Sargasso Sea a century ago, the oceanic migration of adult American eels has remained a mystery. Considering the species’ precarious status, filling the knowledge gap with respect to its marine migration is important for both research and management objectives This implies refining information on the extent of the spawning area, describing the environmental conditions experienced during the migration and revealing the migration routes and orientation cues eels use. Eight eels were successfully tracked to the open ocean off the continental shelf, including one tracked for 2,400 km to the northern limit of the spawning site in the Sargasso Sea. Our results represent the first direct evidence of adult Anguilla migrating to the Sargasso Sea. The similarity of trajectories and behaviour of migrating eels indicate a degree of consistency in the orientation/navigation mechanism employed throughout the migration. Migrating mainly in shallow water over the continental shelf with no marked vertical migratory pattern, eels exhibit DVM down to 700 m in the open ocean

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