Ray bycatch in a tropical shrimp fishery: do bycatch reduction devices and turtle excluder devices effectively exclude rays?

    Onderzoeksoutput: Bijdrage aan tijdschriftA1: Web of Science-artikel


    Worldwide, many species of elasmobranchs (Chondrichthyes: Elasmobranchii) are currently threatenedby marine fisheries activity and are on the Red List of the International Union for Conservation of Nature(IUCN). Although Bycatch Reduction Devices (BRDs) for teleost fish and Turtle Excluder Devices (TEDs) arenow widespread in tropical shrimp trawling, information on their ability to mitigate bycatch of elasmo-branchs, particularly rays (Batoidea), is scarce and limited to only a few isolated fisheries. The objectiveof this study was to evaluate the potential of trawls fitted with a square-mesh panel BRD and super-shooter TED in reducing ray bycatch. In this study, 65 catch-comparison hauls were conducted in theAtlantic seabob shrimp (Xiphopenaeus kroyeri) fishery off Suriname. Trawls with a BRD and TED combi-nation reduced ray catch rate by 36%. A 21% reduction in mean size indicated the preferential exclusionof large rays. Hence, high escape ratios were observed for Dasyatis geijskesi (77%), a large-sized species,while exclusion of the small species Urotrygon microphthalmum was not significant, although their discwidth is small enough to pass through the meshes of the BRD. Furthermore, a size-dependent escapefor the two most abundant mid-sized ray species Dasyatis guttata and Gymnura micrura was observed.Exclusion-at-size differed for both species, however, likely related to species-specific morphology orbehavior in response to the TED. This study shows that the combination of BRD and TED causes an impor-tant reduction in ray bycatch in seabob shrimp fisheries off Suriname. The great reduction in catch oflarge-sized rays is positive, but the mortality of juvenile rays is likely to have negative consequences fortheir populations. We therefore recommend gear-based and non-gear adaptations to further reduce thebycatch of small-sized rays.
    TijdschriftFisheries Research
    Pagina's (van-tot)35-42
    StatusGepubliceerd - 2016

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