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Densities and swimbladder development of juvenile American eels, Anguilla rostrata (Lesueur) as related to energetics of migration
Author(s) -
Hickman R. A.
Publication year - 1981
Publication title -
journal of fish biology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.672
H-Index - 115
eISSN - 1095-8649
pISSN - 0022-1112
DOI - 10.1111/j.1095-8649.1981.tb03792.x
Subject(s) - anguilla rostrata , biology , juvenile , estuary , energetics , fresh water , fishery , hydrostatic pressure , anguillidae , hydrostatic equilibrium , zoology , fish <actinopterygii> , ecology , physics , quantum mechanics , thermodynamics
Glass eels and elvers of the American eel were negatively buoyant. Those adapted to sea water were more dense (1.072 ± 0.001 g cm −3 ) than those adapted to fresh water (1.061 ± 0.001 g cm −3 ). Adaptation to fresh water increased relative body water content, but did not account for the observed decrease in total body density. Histological examination revealed the presence of a potentially functional swimbladder in the glass eels, although this hydrostatic organ did not becomegas‐filled until after freshwater residency had occurred. Calculation of lift as used in the selective tidal transport mechanism suggests that hydrodynamic compensation for horizontal swimming during the estuarine phase of migration is energetically adaptive.