Observations of controlled moving targets with split-beam sonar and implications for detection of migrating adult salmon in rivers

Cronkite, George M.W.; Enzenhofer, Hermann J.

doi:10.1016/s0990-7440(01)01150-0

Cited by 6 publications

(13 citation statements)

References 15 publications

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“…The lower margin of the beam slightly grazed the bottom, potentially causing amplification due to cylindrical spreading of the sound (Rakowitz and Kubečka, 2006). Hence, the signals of bottom-oriented, upstream-migrating fish on the edge of the acoustic beam might also be amplified (Fleischmann and Burwen, 2000;Cronkite and Enzenhofer, 2002) due to interference from acoustic boundaries.…”

Section: Discussionmentioning

confidence: 99%

Two methods to improve the accuracy of target-strength estimates for horizontal beaming

Rakowitz

Herold²,

Fesl

et al. 2008

Fisheries Research

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Section: Discussionmentioning

confidence: 99%

Two methods to improve the accuracy of target-strength estimates for horizontal beaming

Rakowitz

Herold²,

Fesl

et al. 2008

Fisheries Research

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“…Living Resour. 20, 205-212 (2007) loss of data due to interference between targets (see Cronkite and Enzenhofer 2002). Environmental noise and interference between targets can add or remove accepted echoes from fish tracks or cause inaccurate measurement of target position in the beam.…”

Section: Dfa and Effectiveness Of Classifiersmentioning

confidence: 99%

Categorising salmon migration behaviour using characteristics of split-beam acoustic data

Cronkite

Mulligan

Holmes

et al. 2007

Aquat. Living Resour.

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-Milling behaviour is problematic when using hydroacoustics to estimate the number of migrating fish in rivers. Milling behaviour was observed for adult sockeye salmon migrating upstream in the Wannock River, to their spawning grounds in the tributaries of Owikeno Lake in the central coast area of British Columbia, Canada. We classified the acoustic salmon tracks to separate the milling fish from the actively migrating fish in an attempt to obtain an estimate of sockeye salmon flux as they migrate to their spawning grounds. We used discriminant function analysis and found that three variables measured on each track were sufficient for the classification of the acoustic tracks into milling and non-milling categories with an approximate classification accuracy of 98%. The method we present can also be used to separate tracks of targets of interest from noise or debris tracks that occur in the acoustic data, if discrete track characteristics are ascertained.Key words: Split-beam / Acoustic noise / Track characteristics / Discriminant function Résumé -Classification des types de comportement du saumon en migration en utilisant les caractéristiques des données acoustiques d'un sondeur mono-faisceau. Les comportements non-migratoires posent problème quand on veut estimer le nombre de poissons en migration dans les fleuves, en utilisant l'hydroacoustique. Ce comportement non-migratoire est observé chez les saumons rouge (Oncorhynchus nerka) lorsqu'ils remontent le fleuve Wannock pour aller vers leurs aires de ponte situées dans les affluents du lac Owikeno, sur la côte de Colombie Britannique au Canada. Nous classons les suivis (échos-traces) acoustiques des saumons afin de séparer les poissons qui ne migrent pas, des poissons en migration active, dans le but d'obtenir une estimation des flux de saumons rouge lors de leur remontée vers les zones de ponte. Nous utilisons l'analyse de fonction discriminante et nous trouvons que trois variables, mesurées sur chaque déplacement, sont suffisantes pour classer les suivis acoustiques en catégories migrante et non-migrante, avec une précision approximative de 98 %. La méthode que nous présentons peut aussi être utilisée pour séparer les déplacements de cibles présentant un intérêt, des suivis de débris et du bruit présents dans les données acoustiques, si des caractéristiques discrètes sont fixées.

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“…However, the system usually has a very coarse spatial resolution in the cross-range direction, as this resolution is limited by the half-power full beam width of the transducer. When the sound beam detects multiple targets from the same range, the sonar cannot resolve angular positions of these targets in the beam, as demonstrated by Cronkite and Enzenhofer (2002). For individual targets with lateral sizes comparable with the width of the sound beam at the range of detection, the sonar can only estimate point locations of the targets for each transmitted pulse with little information on the detailed geometric shapes of these targets.…”

Section: Introductionmentioning

confidence: 99%

Observations of avoidance reactions of migrating salmon to a mobile survey vessel in a riverine environment

Xie

Michielsens

Gray

et al. 2008

Can. J. Fish. Aquat. Sci.

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Detailed avoidance reactions of adult migrating salmon to a mobile survey vessel were successfully observed with side-looking dual-frequency identification sonar (DIDSON) in the lower Fraser River (British Columbia, Canada). Both adult sockeye (Oncorhynchus nerka) and pink salmon (Oncorhynchus gorbuscha) returning to the river were found to avoid the approaching vessel by initiating lateral movements away from the vessel, making the fish unlikely to be insonified by the downward-looking transducers towed by the vessel. The vessel was found to have an estimated mean interference range of 4 m from its propeller. Analyses of the data concluded that once the vessel and fish were separated by more than 7 m, the vessel no longer affected the normal migration behaviour of the fish.Résumé : Un sonar latéral d'identification à double fréquence (DIDSON) nous a permis d'observer avec succès les réac-tions détaillées d'évitement des saumons adultes en migration face à un navire mobile d'inventaire dans le cours inférieur du Fraser (Colombie-Britannique, Canada). Tant les saumons rouges (Oncorhynchus nerka) que les saumons roses (Oncorhynchus gorbuscha) qui retournent dans la rivière évitent le navire qui s'approche en entreprenant des déplacements latér-aux pour se distancer du navire, ce qui fait que les poissons risquent peu d'être repérés par les capteurs sonar orientés vers le bas et tirés par le navire. La portée moyenne de l'interférence du navire est estimée à 4 m depuis l'hélice. Les analyses de ces données mènent à la conclusion que lorsque le navire et les poissons sont séparés par une distance de plus de 7 m, le navire n'affecte plus le comportement normal de migration des poissons.[Traduit par la Rédaction]

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Observations of controlled moving targets with split-beam sonar and implications for detection of migrating adult salmon in rivers

Cited by 6 publications

References 15 publications

Two methods to improve the accuracy of target-strength estimates for horizontal beaming

Two methods to improve the accuracy of target-strength estimates for horizontal beaming

Categorising salmon migration behaviour using characteristics of split-beam acoustic data

Observations of avoidance reactions of migrating salmon to a mobile survey vessel in a riverine environment

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