Effect of Depth-Dependent Target Strength on Biomass Estimation of Japanese Anchovy

Effect of the depth-dependent target strength (TS) on biomass estimation of Japanese ahcovy was examined by using following four TS models: (1) TS=20logL(subscript t)-71.9, (2) TS=20logL(subscript t)-72.5, (3) TS=20logL(subscript t)-(20/3)log(1+z/10)-67.6 and (4) TS=20logL(subscript t)-(20/3)log(1+ z/10)-64.7, where L(subscript t) and z represent total length (cm) and depth (m), respectively. (1) and (2) have been used in conventional fisheries resources surveys; (3) and (4) take account of depth-dependent TS. Because (1)-(3) were based on in-situ measurement, pitch angles of individuals used in the models were not known. Pitch angle is assumed 0o (±10o std) in (4). Biomass estimated by (3) was 82% and 73% of (1) and (2), respectively. Biomass estimated by (3) was 195% of (4). The results indicated that the effect of the pitch angle on the biomass estimation could be large even if the effect of the depth-dependent TS was taken account. Mean distribution depth can be used as a value for z.

[1]  Arne Johannessen,et al.  Stock size, distribution and biology of anchovy in the Yellow Sea and East China Sea , 1993 .

[2]  赵宪勇.  The acoustic survey of anchovy in the Yellow Sea in February 1999,with emphasis on the estimation of the size structure of the anchovy population , 2001 .

[3]  和男 甘糟,et al.  カタクチイワシ（Engraulis japonicus）の鰾形状およびターゲットストレングスと体長の関係 , 2010 .

[4]  Yong Wang,et al.  Depth-dependent target strength of anchovy (Engraulis japonicus) measured in situ , 2008 .

[5]  Ryuichi Matsukura,et al.  Application of a generalized additive model (GAM) to reveal relationships between environmental factors and distributions of pelagic fish and krill: a case study in Sendai Bay, Japan , 2009 .

[6]  Seiji Ohshimo,et al.  Vertical distribution and acoustic estimation of biomass of walleye pollock Theragra chalcogramma, and anchovy Engraulis japonicus in the Pacific coast of eastern Hokkaido [Japan] , 1996 .

[7]  John K. Horne,et al.  Acoustic models of fish: The Atlantic cod (Gadus morhua) , 1994 .

[8]  Seiji Ohshimo,et al.  Acoustic Estimation of Biomass and School Character of Anchovy Engraulis japonicus in the East China Sea and the Yellow Sea , 1996 .

[9]  Chiyuki Sassa,et al.  Night-time vertical distribution and abundance of small epipelagic and mesopelagic fishes in the upper 100 m layer of the Kuroshio-Oyashio Transition Zone in Spring , 2005, Fisheries Science.

[10]  Ichiro Aoki,et al.  Growth-selective predation hypothesis revisited for larval anchovy in offshore waters: cannibalism by juveniles versus predation by skipjack tunas , 2004 .

[11]  E. Ona,et al.  Modelling the acoustic effect of swimbladder compression in herring , 2003 .

[12]  Seiji Ohshimo,et al.  Spatial distribution and biomass of pelagic fish in the East China Sea in summer, based on acoustic surveys from 1997 to 2001 , 2004 .

[13]  Pierre Fréon,et al.  Some elements on vertical avoidance of fish schools to a vessel during acoustic surveys , 1992 .

[14]  K. Foote.  Fish target strengths for use in echo integrator surveys , 1987 .

[15]  Ryo Kimura,et al.  Vertical distribution of fish larvae in the Kuroshio and Kuroshio-Oyashio transition region in early summer , 2001 .

[16]  G. Jolly,et al.  A Stratified Random Transect Design for Acoustic Surveys of Fish Stocks , 1990 .

[17]  Tomonari Akamatsu,et al.  Measuring the target strength spectra of fish using dolphin-like short broadband sonar signals. , 2008, The Journal of the Acoustical Society of America.

[18]  E. Ona.  An expanded target-strength relationship for herring , 2003 .

[19]  Kouichi Sawada,et al.  Target-strength, length, and tilt-angle measurements of Pacific saury (Cololabis saira) and Japanese anchovy (Engraulis japonicus) using an acoustic-optical system , 2009 .

[20]  I. Aoki,et al.  Photographic observations on the behaviour of Japanese anchovy Engraulis japonica at night in the sea , 1988 .

[21]  Hiroki Yasuma,et al.  Acoustic characterization of biological backscatterings in the Kuroshio-Oyashio inter-frontal zone and subarctic waters of the western North Pacific in spring , 2009 .

[22]  George R. Cutter,et al.  Accounting for scattering directivity and fish behaviour in multibeam-echosounder surveys , 2007 .

[23]  François Gerlotto,et al.  Three-dimensional structure and avoidance behaviour of anchovy and common sardine schools in central southern Chile , 2004 .

[24]  Hiroshi Okamura,et al.  Prey selection of common minke (Balaenoptera acutorostrata) and Bryde's (Balaenoptera edeni) whales in the western North Pacific in 2000 and 2001 , 2007 .