scholarly journals Target-strength, length, and tilt-angle measurements of Pacific saury (Cololabis saira) and Japanese anchovy (Engraulis japonicus) using an acoustic-optical system

2009 ◽  
Vol 66 (6) ◽  
pp. 1212-1218 ◽  
Author(s):  
Kouichi Sawada ◽  
Hideyuki Takahashi ◽  
Koki Abe ◽  
Taro Ichii ◽  
Kazutoshi Watanabe ◽  
...  
Keyword(s):  
Optical System ◽  
Tilt Angle ◽  
Video Camera ◽  
Target Strength ◽  
Japanese Anchovy ◽  
Pacific Saury ◽  
Engraulis Japonicus ◽  
Cololabis Saira ◽  
Angle Measurements ◽  
Stereo Video

Abstract Sawada, K., Takahashi, H., Abe, K., Ichii, T., Watanabe, K., and Takao, Y. 2009. Target-strength, length, and tilt-angle measurements of Pacific saury (Cololabis saira) and Japanese anchovy (Engraulis japonicus) using an acoustic-optical system. – ICES Journal of Marine Science, 66: 1212–1218. Pacific saury and Japanese anchovy generally congregate in dense groups or schools. An acoustic-optical system (the Japanese Quantitative Echosounder and Stereo-video Camera System or J-QUEST) has been developed to measure accurately the target strength (TS) of fish in a dense school. J-QUEST comprises a quantitative, 70 kHz, split-beam echosounder and a stereo-video camera. It was deployed from a research vessel to collect concomitant measures of TS and stereo images of in situ Pacific saury and Japanese anchovy. The stereo-video camera provides estimates of the fish lengths (L) and tilt-angles corrected for J-QUEST motion. In this way, empirical models of TS vs. log(L) were derived for Pacific saury and Japanese anchovy and compared with theory.

scholarly journals Ex situ target-strength measurements of Japanese anchovy (Engraulis japonicus) in the coastal Northwest Pacific

2009 ◽  
Vol 66 (6) ◽  
pp. 1219-1224 ◽  
Author(s):  
Donhyug Kang ◽  
Sungho Cho ◽  
Changwon Lee ◽  
Jung-Goo Myoung ◽  
Jungyul Na
Keyword(s):  
Video Camera ◽  
Ex Situ ◽  
Target Strength ◽  
Northwest Pacific ◽  
Japanese Anchovy ◽  
Least Squares Regression ◽  
Important Species ◽  
Engraulis Japonicus ◽  
Wet Weight ◽  
Underwater Video Camera

Abstract Kang, D., Cho, S., Lee, C., Myoung, J-G. and Na, J. 2009. Ex situ target-strength measurements of Japanese anchovy (Engraulis japonicus) in the coastal Northwest Pacific. – ICES Journal of Marine Science, 66: 1219–1224. The Japanese anchovy (Engraulis japonicus) is an important species in regard to the fisheries and ecology of the coastal Northwest Pacific. Measurements of ex situ target strength (TS; dB re 1 m2) were made on live anchovy using 38, 120, and 200 kHz split-beam echosounders. The fish were tethered using small hooks attached to their mouths. During the acoustic measurements, an underwater video camera was used to continuously monitor fish behaviour and tilt-angle (θ). Data for 35 individual anchovy ranging from immature to adult sizes (total lengths LT = 4.8–12.2 cm) were analysed. Least-squares regression fits of TS vs. log(LT) were: TS38 kHz = 20 log(LT) − 65.8 (r2 = 0.82), TS120 kHz = 20 log(LT) − 68.4 (r2 = 0.84), and TS200 kHz = 20 log(LT) − 69.1 (r2 = 0.71). The LT vs. wet weight (W; g) relationship for these fish was W = 0.0036 LT3.204. The mean θ for anchovy swimming freely in a large seawater tank was 9.1° (s.d. = 13.1°). These ex situ measurements of TS, LT, W, and θ can be applied to improve acoustic estimates of Japanese anchovy biomass.

scholarly journals Measurement and visual verification of fish target strength using an acoustic-optical system attached to a trawlnet

2009 ◽  
Vol 66 (6) ◽  
pp. 1238-1244 ◽  
Author(s):  
Tim E. Ryan ◽  
Rudy J. Kloser ◽  
Gavin J. Macaulay
Keyword(s):  
Optical System ◽  
Deep Water ◽  
Video Camera ◽  
Target Strength ◽  
Dual Frequency ◽  
Low Light ◽  
Orange Roughy ◽  
Video Images ◽  
Acoustic Target ◽  
Frequency Split

Abstract Ryan, T. E., Kloser, R. J., and Macaulay, G. J. 2009. Measurement and visual verification of fish target strength using an acoustic-optical system attached to a trawlnet. – ICES Journal of Marine Science, 66: 1238–1244. It is difficult to make acoustic target-strength (TS) measurements of fish behaving naturally in deep-water habitats. The fish may avoid the acoustic instrumentation, and, if measured, there is uncertainty about their species and their orientation relative to the incident sound. To address these issues, a novel acoustic-optical system (AOS) has been developed, which combines a battery-powered, dual-frequency, split-beam acoustic system with a low-light video camera. The AOS attaches to the headline of a commercial deep-water demersal trawlnet that herds fish past the AOS and to the codend. This paper describes initial trials of the AOS to measure calibrated TS of New Zealand orange roughy, validated with video images. The fish species were visually identified, and their behaviour and orientation were approximated. The trawl catch provided associated samples for species identification and measurements of their length and other biological metrics. The combination of acoustics and optics in a net-mountable system constitutes a powerful sampling tool with broader applications in fishery research and ecosystem investigations.

scholarly journals Swimming angle and target strength of larval Japanese anchovy (Engraulis japonicus)

2011 ◽  
Vol 77 (2) ◽  
pp. 161-167 ◽  
Author(s):  
Yusuke Ito ◽  
Hiroki Yasuma ◽  
Reiji Masuda ◽  
Kenji Minami ◽  
Ryuichi Matsukura ◽  
...  
Keyword(s):  
Target Strength ◽  
Japanese Anchovy ◽  
Engraulis Japonicus

scholarly journals Additional evidence for fisheries acoustics: small cameras and angling gear provide tilt angle distributions and other relevant data for mackerel surveys

2016 ◽  
Vol 73 (8) ◽  
pp. 2009-2019 ◽  
Author(s):  
Paul G. Fernandes ◽  
Phillip Copland ◽  
Rafael Garcia ◽  
Tudor Nicosevici ◽  
Ben Scoulding
Keyword(s):  
Species Identification ◽  
Tilt Angle ◽  
Standard Technique ◽  
Video Camera ◽  
Resource Assessment ◽  
Marine Ecology ◽  
Target Strength ◽  
Angle Distribution ◽  
Frequency Distributions ◽  
Fisheries Acoustics

Abstract Fisheries acoustics surveys are effective tools in marine resource assessment and marine ecology. Significant advances have occurred in recent years with the application of multiple and broadband frequencies to enable remote species identification. There is, however, still the need to obtain additional evidence for identification, and the estimation of the size and tilt angle distribution of fish, which influences their acoustic target strength. The former two requirements are usually met by obtaining simultaneous net samples: there are limited, if any, recognized successful techniques for the latter. Here, two alternative tools for obtaining evidence for all three requirements are examined: angling gear and small video cameras. These tools were deployed during surveys of Atlantic mackerel (Scomber scombrus). In 2014, angling was actually more efficient than pelagic trawling (the standard technique) and over two survey periods (2012 and 2014) provided length frequency distributions that were not significantly different. A small video camera was deployed into mackerel schools, providing species identification and fish orientation. Image analysis was then applied, producing tilt-angle distributions of free swimming wild mackerel for the first time. Mean tilt angles from three deployments were very variable with 95% of observations falling between −70° and 39° with evidence of a multinomial frequency distribution. A video equipped lander was also deployed onto the type of rocky seabed where deployment of a trawl would be impossible: this confirmed the presence of Norway pout and suggested it was the dominant scatterer on this type of seabed. These techniques are complementary to traditional trawling methods, but provide additional insights into fish behaviour whilst satisfying standard requirements of identification and supplying biological samples. Crucially, the small cameras deployed approximate the size of the animals under observation and allow for measurement of behaviour (specifically tilt) that are more likely to represent those conditions encountered during surveying.

scholarly journals Swimbladder Shape and Relationship Between Target Strength and Body Length of Japanese Anchovy (Engraulis japonicus)

2010 ◽  
Vol 37 (1) ◽  
pp. 46-59 ◽  
Author(s):  
Kazuo AMAKASU ◽  
Kazuhiro SADAYASU ◽  
Koki ABE ◽  
Yoshimi TAKAO ◽  
Kouichi SAWADA ◽  
...  
Keyword(s):  
Body Length ◽  
Target Strength ◽  
Japanese Anchovy ◽  
Engraulis Japonicus

scholarly journals Target strength and tilt-angle distribution of the lesser sandeel (Ammodytes marinus)

2012 ◽  
Vol 69 (6) ◽  
pp. 1099-1107 ◽  
Author(s):  
Rokas Kubilius ◽  
Egil Ona
Keyword(s):  
Tilt Angle ◽  
Field Experiments ◽  
Video Camera ◽  
Target Strength ◽  
Fish Length ◽  
Angle Distribution ◽  
Total Uncertainty ◽  
Sea Bottom ◽  
Swimming Pattern ◽  
Acoustic Target

Abstract Kubilius, R., and Ona, E. 2012. Target strength and tilt-angle distribution of lesser sandeel (Ammodytes marinus) – ICES Journal of Marine Science, 69: 1099–1107. North Sea stocks of lesser sandeel have recently become depleted, and improved methods for abundance estimation are sought. This paper focuses on the acoustic target strength (TS) and orientation of sandeel, measured simultaneously in several field experiments. A specially designed cubic cage, fitted with an echosounder and a video camera, was lowered onto the sea bottom, trapping wild sandeel inside. Methods for manually selecting valid echotraces from individual sandeel are described. Scattered mean TS values from several experiments are reported. These are, in spite of the observed variability, summarized in a TS–fish length (cm) relationship as TS = 20logL – 93.1 (dB) at 200 kHz. We believe that the accuracy of the relationship may still be debated; incorporating larger uncertainty in the overall mean TS will increase the total uncertainty of the stock biomass estimate from sandeel acoustic surveys. This uncertainty is now, using standard narrow-beam echosounders, dominated by the fish patchiness relative to the survey coverage. Results from pilot investigations of the sandeel swimming orientation using video cameras are also presented, showing that sandeel usually has an anguilliform swimming pattern with substantial positive (head-up) tilt. The spread of the tilt-angle distribution is also larger than for more neutrally buoyant fishes.

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