MEPS 554:141-155 (2016)  -  DOI:

Hydrographic features of anguillid spawning areas: potential signposts for migrating eels

Robert Schabetsberger1,*, Michael J. Miller2, Giorgio Dall’Olmo3, Roland Kaiser1, Finn Økland4, Shun Watanabe2, Kim Aarestrup5, Katsumi Tsukamoto2

1Department of Cell Biology, University of Salzburg, 5020 Salzburg, Austria
2College of Bioresource Sciences, Nihon University, Kanagawa 52-0880, Japan
3Plymouth Marine Laboratory, Plymouth PL1 3DH, UK
4The Norwegian Institute of Nature Research, 7047 Trondheim, Norway
5National Institute of Aquatic Resources, Technical University of Denmark, 8600 Silkeborg, Denmark
*Corresponding author:

ABSTRACT: Catadromous anguillid eels (genus Anguilla) migrate from their freshwater or estuarine habitats to marine spawning areas. Evidence from satellite tagging studies indicates that tropical and temperate eel species exhibit pronounced diel vertical migrations, from between 150-300 m nighttime depths to 600-800 m during the day. Collections of eggs and larvae of Japanese eels A. japonica suggest they may spawn at these upper nighttime migration depths. How anguillid eels navigate through the ocean and find their spawning areas remains unknown; thus, this study describes the salinity, temperature and geostrophic currents between 0 and 800 m depths within 2 confirmed and 3 hypothetical anguillid spawning areas during likely spawning seasons. Within the 4 ocean gyres in which these spawning areas are located, many eels would encounter subducted ‘Subtropical Underwater’ water masses during their nighttime ascents that could provide odor plumes as signposts. Four of the spawning areas are located near the western margins of where subducted water masses form cores of elevated salinities (~35.0 to 36.8) around 150 m depths, and one is located near the center of subduction. Low salinity surface waters and fronts are present in some of the areas above the high-salinity cores. Spawning may occur at temperatures between 16 and 24°C where the thermocline locally deepens. At spawning depths, weak westward currents (~0 to 0.1 m s-1) prevail, and eastward surface countercurrents are present. Anguillid eels possess acute sensory capabilities to detect these hydrographic features as potential signposts, guiding them to their spawning areas.

KEY WORDS: Anguilla · Diel vertical migration · Orientation · Satellite telemetry · Spawning

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Cite this article as: Schabetsberger R, Miller MJ, Dall’Olmo G, Kaiser R and others (2016) Hydrographic features of anguillid spawning areas: potential signposts for migrating eels. Mar Ecol Prog Ser 554:141-155.

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