Repelling charges are small explosive charges detonated to frighten and drive fish away from a blasting zone just prior to detonation of a major explosive charge. Use of repelling charges has been recommended by natural resource agencies to mitigate the effects of submerged explosives. Blasting companies have used this technique in a 'good faith effort' to reduce potential damages to aquatic resources. It has been assumed that noise or pressure generated by the small charge will drive fish from the immediate area, thereby reducing impacts from the much larger and potentially more-damaging blast. We evaluated the effectiveness of repelling charges in moving radio-tagged largemouth bass (Micropterus salmoides), channel catfish (Ictalurus punctatus) and flathead catfish (Pylodictis olivaris). Movement distances were used to estimate the proportions of fish which would theoretically move out of computed kill zones associated with detonation of large charges of high explosives. Largemouth bass (n = 15) showed little response to repelling charges and none would have moved out of the kill zone calculated for any explosive size. Only two of six flathead catfish tested would have moved to a safe zone based on the kill radius calculated for the smallest theoretical blast weight. This charge size is smaller than would be used for demolition work, for example. Only one flathead catfish would have moved from the kill zone produced by a demolition blast. Two of seven channel catfish tested moved out of the kill zone. Study results are consistent with published observations of the response of fish schools to underwater explosions.


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    Title :

    Are repelling charges effective in mitigating the impacts of underwater explosions?


    Additional title:

    Sind Abschrecksprengsätze wirkungsvoll bei der Milderung der Auswirkungen von Unterwasserexplosionen?


    Contributors:


    Publication date :

    1997


    Size :

    11 Seiten, 2 Tabellen, 25 Quellen


    Type of media :

    Conference paper


    Type of material :

    Print


    Language :

    English




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