Problems with acoustic target strength measurements of a deepwater fish, orange roughy (Hoplostethus atlanticus, Collett)

1997 ◽  
Vol 54 (1) ◽  
pp. 60-71 ◽  
Author(s):  
R Kloser
Keyword(s):  
Target Strength ◽  
Orange Roughy ◽  
Acoustic Target ◽  
Hoplostethus Atlanticus

Target strength of an oily deep-water fish, orange roughy (Hoplostethus atlanticus) I. Experiments

1999 ◽  
Vol 106 (1) ◽  
pp. 131-142 ◽  
Author(s):  
Sam McClatchie ◽  
Gavin Macaulay ◽  
Roger F. Coombs ◽  
Paul Grimes ◽  
Alan Hart
Keyword(s):  
Deep Water ◽  
Target Strength ◽  
Orange Roughy ◽  
Water Fish ◽  
Hoplostethus Atlanticus

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.

Acoustic assessment of the biomass of a spawning aggregation of orange roughy (Hoplostethus atlanticus, Collett) off south-eastern Australia, 1990-93

1996 ◽  
Vol 47 (8) ◽  
pp. 1015 ◽  
Author(s):  
RJ Kloser ◽  
JA Koslow ◽  
A Williams
Keyword(s):  
Management Strategy ◽  
Sampling Error ◽  
Target Strength ◽  
Acoustic Beam ◽  
Orange Roughy ◽  
Eastern Australia ◽  
Acoustic Surveys ◽  
Surface Bubble ◽  
Hoplostethus Atlanticus

Orange roughy, which spawn in an aggregation around a seamount off north-eastem Tasmania, were surveyed acoustically with vessel-mounted and deep-tow transducers from 1990 to 1993. Orange roughy dominated at 700-900 m (95% of individuals) and were less numerous both shallower and deeper. Echo integration estimates from the vessel-mounted transducer were consistently lower than those from the deep-tow transducer by a factor of ~1.8, owing to surface bubble attenuation, vessel movement and acoustic beam thresholding among other factors. The absolute estimate from the deep-towed transducer of the prefishery orange roughy biomass (98200 t ; coefficient of variation, 6.7%) compared well with estimates from stock reduction analysis (95000 to 110000 t) and an egg survey (96900 t; CV, 47%). The acoustic surveys had lower sampling error (CV, 7-15%) than that of the egg survey and required less survey time. The present results support the use of initial absolute acoustic biomass estimates to set a management strategy for the fishery. Stock reduction analysis based on the relative acoustic estimates and catch over the four years indicated that orange roughy target strength was -50 dB � 3 dB, which is consistent with results from models of target strength and from measurements in situ and on dead specimens.

In situ measurements of orange roughy (Hoplostethus atlanticus) target strength

2007 ◽  
Vol 64 (6) ◽  
pp. 1220-1234 ◽  
Author(s):  
Roger F. Coombs ◽  
Richard Barr
Keyword(s):  
New Zealand ◽  
Standard Length ◽  
In Situ Measurements ◽  
Rate Of Change ◽  
Target Strength ◽  
Commercial Fisheries ◽  
Orange Roughy ◽  
Wide Range ◽  
Hoplostethus Atlanticus

Abstract Coombs, R. F., and Barr, R. 2007. In situ measurements of orange roughy (Hoplostethus atlanticus) target strength. – ICES Journal of Marine Science, 64: 1220–1234. Orange roughy (Hoplostethus atlanticus) support one of New Zealand's most valuable commercial fisheries, and its assessment poses many problems. Acoustic estimation using echo integration has become one of the main sources of biomass information, and for this an estimate of orange roughy target strength (TS) is needed. Its schooling characteristics together with patterns in the rate of change of phase vs. TS plots are used to identify ensembles of orange roughy targets from in situ TS data collected from a wide range of fishing areas off eastern New Zealand. The results suggest a TS of −49.3 dB for an orange roughy of 35 cm standard length.

Identification and target strength of orange roughy (Hoplostethus atlanticus) measuredin situ

2013 ◽  
Vol 134 (1) ◽  
pp. 97-108 ◽  
Author(s):  
Rudy J. Kloser ◽  
Gavin J. Macaulay ◽  
Tim E. Ryan ◽  
Mark Lewis
Keyword(s):  
Target Strength ◽  
Orange Roughy ◽  
Hoplostethus Atlanticus

Use of acoustics to assess a small aggregation of orange roughy, Hoplostethus atlanticus (Collett), off the eastern coast of Tasmania

1993 ◽  
Vol 44 (3) ◽  
pp. 473 ◽  
Author(s):  
NG Elliott ◽  
RJ Kloser
Keyword(s):  
Target Strength ◽  
Eastern Coast ◽  
Orange Roughy ◽  
Commercial Catch ◽  
Acoustic Data ◽  
The Mean ◽  
Small Aggregation ◽  
Hoplostethus Atlanticus ◽  
Echo Sounder

A relatively small aggregation of orange roughy (Hoplostethus atlancticus) was located in April 1989 off the eastern coast of Tasmania. A Simrad EK400 (38 kHz) scientific echo-sounder was used to survey the aggregation over a period of eight days, during which time the aggregation was commercially fished. The aggregation was confined to an area of approximately 4 km2, with the dimensions of the aggregation varying within and between days. High densities of orange roughy were located near the bottom on some days and more than 24 m off the bottom on others. Average fish densities during the survey and an estimate of the extremes of densities (fish m-3) are presented. Estimates of the original biomass of this aggregation as obtained from acoustic data and commercial catch-and-effort data are compared, and the mean target strength of the population is estimated.

scholarly journals Characterizing uncertainty in target-strength measurements of a deepwater fish: orange roughy (Hoplostethus atlanticus)

2003 ◽  
Vol 60 (3) ◽  
pp. 516-523 ◽  
Author(s):  
R.J Kloser ◽  
J.K Horne
Keyword(s):  
Active Avoidance ◽  
Target Selection ◽  
Target Strength ◽  
Wax Ester ◽  
Fish Length ◽  
Orange Roughy ◽  
Single Target ◽  
Species Specific ◽  
Hoplostethus Atlanticus

Abstract The variability of ensemble 38 kHz, target-strength (TS38) estimates for orange roughy (Hoplostethus atlanticus) (4.9 dB, factor of 3.1) in deep water (>600 m) limits the use of echo integration for absolute-biomass estimates. Orange roughy are high in oil content, have a wax-ester swimbladder, and show an active-avoidance response to sampling gear. The interpretations of ensemble, in situ target strengths of orange roughy (range 〈TS38〉=−52.9 to −51.0 dB for standard fish length 〈SL〉 = 35 cm) are lower than previous model and surface-based measurements (〈TS38〉 = −48 dB, SL = 35 cm). In situ TS measurements from individuals on the periphery of dense schools were processed to minimize uncertainties from single-target selection criteria, species composition, and active avoidance. Video and acoustic-tracking data quantified the variability in TS measurements arising from the variability in fish orientation. Multi-frequency acoustics and fish tracking are used to quantify in situ TS variability due to species identification and fish density. The Kirchhoff-ray-mode backscatter model was used to illustrate the sensitivity of species-specific backscatter to assumptions of tilt-angle and material properties (density and sound-speed contrasts). We conclude that a remaining source of uncertainty for in situ TS measurements is the assumption that dispersed targets are representative of the survey population.

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