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Measurements of density contrast and sound-speed contrast for target strength estimation of Neocalanus copepods (Neocalanus cristatus and Neocalanus plumchrus) in the North Pacific Ocean

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Title: Measurements of density contrast and sound-speed contrast for target strength estimation of Neocalanus copepods (Neocalanus cristatus and Neocalanus plumchrus) in the North Pacific Ocean
Other Titles: 北太平洋におけるNeocalanus属カイアシ類(N. cristatusおよびN. plumchrus)の理論ターゲットストレングス推定に必要な密度比, 音速比の測定
Authors: Matsukura, Ryuichi1 Browse this author
Yasuma, Hiroki2 Browse this author
Murase, Hiroto3 Browse this author
Yonezaki, Shiroh4 Browse this author
Funamoto, Tetsuichiro5 Browse this author
Honda, Satoshi6 Browse this author
Miyashita, Kazushi7 Browse this author →KAKEN DB
Authors(alt): 松倉, 隆一1
安間, 洋樹2
村瀬, 弘人3
米崎, 史朗4
船本, 鉄一郎5
本田, 聡6
宮下, 和士7
Keywords: Copepod
Density contrast
Neocalanus cristatus
Neocalanus plumchrus
Signal-to-noise ratio
Sound-speed contrast
Target strength
Issue Date: Nov-2009
Publisher: Springer Japan
Journal Title: Fisheries Science
Volume: 75
Issue: 6
Start Page: 1377
End Page: 1387
Publisher DOI: 10.1007/s12562-009-0172-3
Abstract: The mass density and sound-speed contrasts against surrounding seawater (g and h, respectively) of Neocalanus copepods (N. cristatus and N. plumchrus) were measured in 2006 and 2007 to compute the theoretical target strength (TS). The values of g ranged from 0.997 - 1.009 in N. cristatus and from 0.995 - 1.009 in N. plumchrus. There were no correlations in prosome length (PL) and g. The values of h ranged from 1.006 - 1.021 in N. cristatus and 1.013 - 1.025 in N. plumchrus and varied by changes in temperature. TS were estimated by theoretical sound scattering model with the values of g and h that computed by temperature, salinity, and depth where the specimens were collected. Regressions of the tilt averaged TS vs. PL were obtained at 38, 120, and 200 kHz. The averaged TS of N. cristatus and N. plumchrus at 120 kHz, which is widely used as a high frequency, were ranged from -110.0 to -103.1 dB and from -121.4 to -109.7 dB. The higher the frequency was, the higher the value of averaged TS. The differences of TS at 120 and 38 kHz varied from 14.8 to 16.4 dB in N. cristatus, from 17.9 to 18.7 dB in N. plumchrus. The differences of TS at 200 and 120 kHz varied from 2.9 to 5.5 dB in N. cristatus, from 5.3 to 6.5 dB in N. plumchrus.
Neocalanus属カイアシ類の理論ターゲットストレングス(TS)を推定するため,海水との密度比g, 音速比hを測定した。N. cristatusとN. plumchrusのgの範囲は0.997~1.009, 0.995~1.009で体長との相関はみられなかった。一方hは1.006~1.021, 1.013~1.025の範囲で水温による変化がみられた。採集深度における水温, 塩分, 深度から計算したg, hを用い, DWBAモデルにより周波数38, 120, 200kHzにおける理論TSと体長の回帰式を得た。
Rights: © 2009 公益社団法人日本水産学会
© 2009 The Japanese Society of Fisheries Science
The final publication is available at www.springerlink.com
Type: article (author version)
URI: http://hdl.handle.net/2115/40066
Appears in Collections:北方生物圏フィールド科学センター (Field Science Center for Northern Biosphere) > 雑誌発表論文等 (Peer-reviewed Journal Articles, etc)

Submitter: 宮下 和士

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