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ID 48821
file
title alternative
Horizontal distribution and annual fluctuations in abundance of settled juveniles of the black sea bream Acanthopagrus schlegelii in Hiroshima Bay, Japan
creator
Kawai, Kentaro
Fujita, Hiroki
subject
クロダイ
砂浜海岸
稚魚
広島湾
black sea bream
Hiroshima Bay
juvenile
sandy beach
abstract
広島湾においてクロダイ稚魚の着底・成育に適した環境条件を把握する目的で,同湾沿岸の稚魚の生息密度を明らかにした。稚魚は2006–2009年6–7月に広島湾内18定点で採集した(n=2,488)。さらに,調査定点のうち最も高い稚魚密度(35.83 inds./100m2)を観測した能美島鹿田において,2013–2016年の7–9月にかけて稚魚を採集し(n=1,588),密度の年変動を観察した。その結果,広島湾の全平均密度は3.78 inds./100m2となり,密度の高い4定点はいずれも厳島,能美島西岸であった。密度が高い定点の特徴として,潮流が物理的に遮られた静穏域の砂浜帯で,淡水流入があることが挙げられた。密度には年変動があり,近年は減少傾向にあることが判明した。広島湾クロダイの資源加入量が低下している可能性が示唆された。
abstract
To obtain basic information on the optimal nursery grounds for black sea bream Acanthopagrus schlegelii recruits, juvenile density in Hiroshima Bay was calculated. Juveniles (n=2,488) were collected from 18 sampling stations around Hiroshima Bay using surf zone nets during the early summer from 2006 to 2009. to assess the annual fluctuations of juvenile density, samples were continuously caught from one station (St. 1) on the western side of Noumishima Island from 2013 to 2016. Relatively high densities were recorded from four stations (St. 1, 2, 6 and 10) located along the Ohno Seto Strait and the western side of Noumishima Island. These sampling stations shared three common characteristics that likely explain the observed higher juvenile density, namely (1) moderate currents with calm areas protected by physical barrier, (2) sandy muddy beaches (tidal flats) and (3) freshwater inflows or run-off. Juvenile density showed an annual decreasing trend, suggesting that fish stock levels of black sea bream are declining in Hiroshima Bay.
journal title
Bulletin of the Hiroshima University Museum
issue
Issue 11
start page
1
end page
5
date of issued
2019-12-25
publisher
広島大学総合博物館
issn
1884-4243
ncid
language
jpn
nii type
Departmental Bulletin Paper
HU type
Departmental Bulletin Papers
DCMI type
text
format
application/pdf
text version
publisher
rights
Copyright (c) 2019 広島大学総合博物館 Hiroshima University Museum
department
Hiroshima University Museum
Graduate School of Integrated Sciences for Life
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