Ontogenetic diet shift, feeding rhythm, and daily ration of juvenile yellowfin goby Acanthogobius flavimanus on a tidal mudflat in the Tama River estuary, central Japan |
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Authors: | Kouki Kanou Mitsuhiko Sano Hiroshi Kohno |
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Institution: | (1) Department of Global Agricultural Sciences, Graduate School of Agricultural and Life Sciences, The University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo 113-8657, Japan;(2) Laboratory of Ichthyology, Tokyo University of Marine Science and Technology, 4-5-7 Konan, Minato-ku, Tokyo 108-8477, Japan;(3) Present address: Japan Wildlife Research Center, 3-10-10 Shitaya, Taito-ku, Tokyo 110-8676, Japan |
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Abstract: | To ascertain the feeding habits of benthic juvenile yellowfin goby Acanthogobius flavimanus, the gut contents of 599 specimens (15–41 mm in standard length, SL), collected on a tidal mudflat in the Tama River estuary
throughout the diel cycle, were examined. The major prey items changed from harpacticoid copepods to errant and sedentary
polychaetes at ca. 20 mm SL. Prey width increased with fish size. Fish of 26–28 mm SL fed mainly from sunset to morning, with
highest feeding intensity during twilight hours and/or high tide. Based on the gut evacuation rate estimated from a forced
feeding experiment in the laboratory and data for the diel change of mean gut-content volume in the field, the daily ration
of juvenile yellowfin goby (26–28 mm SL) was calculated to be 13.8 mm3 fish−1 day−1. This volume is approximately equivalent to 3.9 individuals of the errant polychaete Ceratonereis erythraeensis (9.7 mm in body length, BL) or 8.1 individuals of the sedentary polychaete Prionospio japonica (14.8 mm BL), both species occurring abundantly on the mudflat during the study. |
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Keywords: | Acanthogobius flavimanus Diet Ontogenetic change Diel cycle Daily ration |
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