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Research article - Peer-reviewed, 2019

Larval size-distributions of Ariosoma balearicum cryptic species during the March-April season in the Sargasso Sea Subtropical Convergence Zone

Miller, Michael J.; Marohn, Lasse; Wysujack, Klaus; Bonhommeau, Syh Ain; Kuroki, Mari; Freese, Marko; Pohlmann, Jan-Dag; Watanabe, Shun; Blancke, Tina; Weist, Peggy; Castonguay, Martin; Westerberg, Hakan; Tsukamoto, Katsumi; Hanel, Reinhold


Leptocephali of the shallow-water congrid eel Ariosoma balearicum are abundant during February-April in the Sargasso Sea, and larval and adult meristic data indicates this species includes several regional subpopulations/cryptic species. Four multiple-transect larval surveys (2011, 2014, 2015, 2017) were used to examine the geographic size distribution of two myomere-count types of A. balearicum leptocephali. High-count (HC) larvae were consistently mostly between 80 and 100 mm in size (60-132 mm; 87.9 +/- 6.8 mm) as observed previously, and frequently had narrow size ranges. The usually larger LC larvae (78-176 mm; 111.4 +/- 26.7 mm) were more abundant in western or central areas. HC larvae tended to decrease in size from west to east and increase from south to north. Catch rates were geographically variable relative to hydrographic structure/frontal positions across the wide 2015 sampling area. Mitochondrial 16 s rRNA sequences of HC and LC larvae show species-level differences, providing evidence of the existence of two cryptic species with different larval dispersal strategies in the Sargasso Sea subtropical gyre region. The HC larvae disperse widely into the gyre, seemingly through Gulf Stream recirculation or eastward frontal-jet flows, and apparently must use directional swimming to cross the Florida Current to recruit into the South Atlantic Bight. LC leptocephali may mostly be retained near the Bahamas, with few larvae dispersing into the gyre. This seems to indicate natural selection occurred for spawning location and larval behavior due to the powerful Florida Current/Gulf Stream, resulting in two completely different spawning and larval dispersal strategies within a local geographic region.


Ariosoma balearicum; Leptocephali; Larval dispersal; Sargasso Sea; Subtropical gyre; Cryptic species

Published in

Environmental Biology of Fishes
2019, volume: 102, number: 10, pages: 1231-1252
Publisher: SPRINGER

Authors' information

Miller, Michael J.
University of Tokyo
Marohn, Lasse
Johann Heinrich von Thunen Institute
Wysujack, Klaus
Johann Heinrich von Thunen Institute
Bonhommeau, Syh Ain
Kuroki, Mari
University of Tokyo
Freese, Marko
Johann Heinrich von Thunen Institute
Pohlmann, Jan-Dag
Johann Heinrich von Thunen Institute
Watanabe, Shun
Kindai Univ
Blancke, Tina
Johann Heinrich von Thunen Institute
Weist, Peggy
Johann Heinrich von Thunen Institute
Castonguay, Martin
Fisheries and Oceans Canada
Swedish University of Agricultural Sciences, Department of Aquatic Resources
Tsukamoto, Katsumi
University of Tokyo
Hanel, Reinhold
Johann Heinrich von Thunen Institute

UKÄ Subject classification

Fish and Aquacultural Science
Fish and Aquacultural Science

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