Journal of the Graduate School of Biosphere Science, Hiroshima University Volume 47
2008-12-20 発行

太田川河口域における小型曳き網のスズキ仔稚魚採集効率の推定

Estimation of catch efficiency of a small seine for larval and juvenile Japanese sea bass, Lateolabrax japonicus, in the Ohta estuary
Iwamoto, Yuji
Morita, Takuma
Kamimura, Yasuhiro
Hirai, Kotaro
file
abstract
In order to estimate catch efficiency of a small seine (1.0 by 2.3 m, 2 mm mesh aperture) for larval and juvenile Japanese sea bass Lateolabrax japonicus, results from experimental hauls of the small seine were compared with those from a large seines (1.0 by 16 m, 2.5 mm mesh aperture) in the Ohta Diversion Channel on March 21 and April 7, 2008. A total of 1,502 Japanese sea bass, ranging between 14.5 and 24.0 mm in standard length were collected. Data of fish <15.9 mm was excluded from the analysis since extrusion of these fish through the mesh of the large seine was possible. Comparison of the Japanese sea bass abundance at lengths between the small and large seines revealed that the catch efficiency of the small seine for Japanese sea bass <18.0 mm was approximately 100%. The catch efficiency decreased with the increase in fish body length between 18.0 and 22.9 mm. A linear model was fitted to the relationship between the catch efficiency (C, %) and body length (L, mm): C=-17.2*L+388.8 (n=11, r2=0.77, p=0.0004). Catch efficiency was not estimated for Japanese sea bass > 23 mm since their abundance was quite low in the surveyed area probably due to migration to downriver or sea areas, which are considered as habitats for the following life stages.
subject
スズキ
仔稚魚
採集効率
小型曳き網
Japanese sea bass
larvae and juveniles
catch efficiency
seine