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Acoustic characterization of biological backscatterings in the Kuroshio‐Oyashio inter‐frontal zone and subarctic waters of the western North Pacific in spring
Author(s) -
MURASE HIROTO,
ICHIHARA MORIO,
YASUMA HIROKI,
WATANABE HIKARU,
YONEZAKI SHIROH,
NAGASHIMA HIROSHI,
KAWAHARA SHIGEYUKI,
MIYASHITA KAZUSHI
Publication year - 2009
Publication title -
fisheries oceanography
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.016
H-Index - 80
eISSN - 1365-2419
pISSN - 1054-6006
DOI - 10.1111/j.1365-2419.2009.00519.x
Subject(s) - subarctic climate , oceanography , mesopelagic zone , pelagic zone , echo sounding , geology , krill , spring (device) , mechanical engineering , engineering
The acoustic characteristics of biological backscattering in the western North Pacific were studied to verify expert knowledge on species composition in the echosigns. The survey was conducted in the Kuroshio‐Oyashio inter‐frontal zone and the subarctic waters in April 2003. The species composition of backscatterings was identified by using midwater trawl, Isaacs‐Kidd midwater trawl and Bongo net. The differences of mean volume backscattering strengths between 120 and 38 kHz (ΔMVBS 120−38 ) were calculated for the backscatterings. Six types of backscatterings were classified based on the results of net samples and the ΔMVBS 120−38 . The ΔMVBS 120−38 of each group was as follows: copepods 13.7–17.3 dB, krill 11.6–15.3 dB, Japanese anchovy −1.6 to 1.1 dB, a myctophid, Diaphus theta −0.8 dB, sand lance 6.1 dB and larvae and juveniles of pelagic and mesopelagic fish −9.6 to −4.0 dB. The results suggest that biological backscatterings in the Kuroshio‐Oyashio inter‐frontal zone and subarctic waters of the western North Pacific in spring can be characterized by using ΔMVBS.