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

Schabetsberger, R; Miller, MJ; Dall’Olmo, G; Kaiser, R; Økland, F; Watanabe, S; Aarestrup, K; Tsukamoto, K. 2016 Hydrographic features of anguillid spawning areas: potential signposts for migrating eels. Marine Ecology Progress Series, 554. 141-155. https://doi.org/10.3354/meps11824

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Official URL: http://dx.doi.org/10.3354/meps11824

Abstract/Summary

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 (similar to 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 degrees C where the thermocline locally deepens. At spawning depths, weak westward currents (similar to 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.

Item Type: Publication - Article
Subjects: Conservation
Fisheries
Oceanography
Divisions: Plymouth Marine Laboratory > National Capability categories > National Centre for Earth Observation
Plymouth Marine Laboratory > Science Areas > Earth Observation Science and Applications
Depositing User: Giorgio Dall'Olmo
Date made live: 20 Nov 2017 11:29
Last Modified: 22 Feb 2018 12:51
URI: http://plymsea.ac.uk/id/eprint/7349

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