Experiences with multibeam sonar in shallow tropical waters

Gerlotto, François; Hernández, Carlos; Linares, E. O.

doi:10.1016/s0165-7836(98)00069-1

Cited by 10 publications

(6 citation statements)

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“…However, with continued improvements in analysis techniques, we think it likely that resolution toward species identification will be achieved, particularly for systems low in species richness. As highlighted by Gerlotto et al (1998), the combination of both multibeam sonar and fishery echo sounders have the potential to provide the most complete and quantitative assessment of fish. Furthermore, the foundation presented here will support additional analytical procedures and techniques for incorporating DIDSON technology into routine surveys.…”

Section: Discussionmentioning

confidence: 99%

A Semiautomated Approach to Estimating Fish Size, Abundance, and Behavior from Dual‐Frequency Identification Sonar (DIDSON) Data

Boswell

Wilson²,

Cowan

2008

N American J Fish Manag

110

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We present a semiautomated analytical approach incorporating both image and acoustic processing techniques to apply to dual‐frequency identification sonar (DIDSON) data. Our objectives were (1) to develop a standardized analysis pathway in order to reduce the effort associated with counting, measuring, and tracking fish targets; and (2) to empirically obtain estimates of basic target information (e.g., size, abundance, speed, and direction of travel). Analyses were conducted on DIDSON data collected at three different locations (the Kenai River, Alaska; Mobile River, Alabama; and Port Fourchon, Louisiana) with different equipment and deployment configurations. We developed an efficient postprocessing approach that can be applied to a variety of data sets, independent of user and deployment method. For two of the three data sets analyzed, the estimates of fish abundance derived from DIDSON analyses were not significantly different from the manual counts of DIDSON files. The analyses produced estimates of mean fish length, direction and speed of travel, and target surface area for all targets within each data set. A consistent analysis platform increases the acceptance and reliability of the DIDSON as a tool for fisheries surveys and further demonstrates the usefulness of DIDSON technology in fisheries applications.

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Section: Discussionmentioning

confidence: 99%

A Semiautomated Approach to Estimating Fish Size, Abundance, and Behavior from Dual‐Frequency Identification Sonar (DIDSON) Data

Boswell

Wilson²,

Cowan

2008

N American J Fish Manag

110

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“…Thorne, 1983;Kubecka and Wittingerova, 1998;Knudsen and Saegrov, 2002), or multibeam sonars (Gerlotto et al, 1998). However, quantifying the horizontal and sonar techniques can be sensitive to weather conditions (MacLennan and Simmonds, 1992;Gerlotto et al, 1998;Knudsen and Saegrov, 2002). Furthermore, both vertical and horizontal acoustic surveys are likely to cause avoidance reactions if the study is conducted from a vessel or float (e.g.…”

Section: Introductionmentioning

confidence: 99%

Diel patterns in pelagic fish behaviour and distribution observed from a stationary, bottom-mounted, and upward-facing transducer

Axenrot

Didrikas

Danielsson

et al. 2004

ICES Journal of Marine Science

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S. 2004. Diel patterns in pelagic fish behaviour and distribution observed from a stationary, bottom-mounted, and upward-facing transducer. e ICES Journal of Marine Science, 61: 1100e1104.Diel variation in pelagic fish distribution influences hydroacoustic abundance estimates. To study and quantify diel patterns in behaviour and spatial distribution in pelagic fish without causing avoidance reactions or attraction to any floating equipment or vessel we used a bottom-mounted, upward-facing transducer. Light intensities were measured as skylight and underwater light (at 5-m depth). The study was performed in a coastal area in the Baltic Sea, late July to mid-August in 2001 and 2002. The results provided additional information on fish behaviour and distribution valuable for future survey planning and in the analyses of hydroacoustic data from regular surveys in this area. At night, the data on hydroacoustic backscattering (s A ) were less variable, the vertical distribution of fish was more even, with fewer fish in the deepest layer, and the percentage of single-echo detections was higher. The tilt angle of fish seemed to differ day and night, but trawling and target-strength distribution results taken together also implied a partial diel change in the fish assemblage in the midwater layers. The processes of formation and disintegration of schools happened rapidly and coincided with day and night transition periods.

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“…However, multibeam devices have been used to monitor fish populations in shallow waters (Gerlotto et al 1998;Guillard 1998;Brehmer et al 2006bBrehmer et al , 2011b. Some multibeam sonar integrates TS values, but its large physical dimensions and capacities can only be used by offshore scientific vessels for now (Trenkel et al 2008).…”

Section: Advantagesmentioning

confidence: 99%

“…Recent sonars increase the number of beams, and then widen the angle of detection, increasing the echogram resolution (Gerlotto et al 1999(Gerlotto et al , 2000Brehmer et al 2011b), but cannot easily measure TS of single targets, unlike split-beam echosounders. However, multibeam devices have been used to monitor fish populations in shallow waters (Gerlotto et al 1998;Guillard 1998;Brehmer et al 2006bBrehmer et al , 2011b. Some multibeam sonar integrates TS values, but its large physical dimensions and capacities can only be used by offshore scientific vessels for now (Trenkel et al 2008).…”

Section: Advantagesmentioning

confidence: 99%

The use of acoustic cameras in shallow waters: new hydroacoustic tools for monitoring migratory fish population. A review of DIDSON technology

et al. 2014

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European Union legislation, through the Water Framework Directive (2000/60/ EC), as well as national legislation, such as the 'Grenelle Environnement ' (2007) in France, requires restoration of ecological connectivity in streams to improve free circulation of migratory fish. Different methods (e.g. capture by trap or net, telemetry, hydroacoustics) are used to evaluate the efficiency of fish passes to estimate the migratory species abundance and analyse changes in their within-river distributions. Among these methods, hydroacoustics is non-intrusive, allowing long-term observation and description of fish populations based on physical properties of sound in water. However, the main limit to hydroacoustic tools is their difficulty in identifying species. Initially designed for military purposes, dual-frequency identification sonar (DIDSON) has been used in environmental management for a decade. This acoustic camera uses higher frequencies and more sub-beams than common hydroacoustic tools, which improves image resolution and then enables observation of fish morphology and swimming behaviour. The ability to subtract static echoes from echograms and directly measure fish length improve the species-identification process. However, some limits have been identified, such as automatic dataset recording and the low range of the detection beam, which decreases accuracy, but efficient tools are now being developed to improve the accuracy of data recording (morphology, species identification, direction and speed). The new technological properties of acoustic cameras, such as the video-like visualization of the data, have greatly improved monitoring of diadromous fish populations (abundance, distribution and behaviour), helping river and fisheries managers and researchers in making decisions.

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Experiences with multibeam sonar in shallow tropical waters

Cited by 10 publications

References 0 publications

A Semiautomated Approach to Estimating Fish Size, Abundance, and Behavior from Dual‐Frequency Identification Sonar (DIDSON) Data

A Semiautomated Approach to Estimating Fish Size, Abundance, and Behavior from Dual‐Frequency Identification Sonar (DIDSON) Data

Diel patterns in pelagic fish behaviour and distribution observed from a stationary, bottom-mounted, and upward-facing transducer

The use of acoustic cameras in shallow waters: new hydroacoustic tools for monitoring migratory fish population. A review of DIDSON technology

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