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    Using digital video monitoring systems in fisheries: applications for monitoring compliance of seabird avoidance devices and seabird mortality in Pacific halibut longline fisheries

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    Número de documento:
    R.T. Ames, G.H. Williams and S.M. Fitzgerald (USA)
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    The National Marine Fisheries Service (NMFS) contracted with the International Pacific Halibut Commission (IPHC) for a project examining the feasibility of electronic monitoring systems (EMS) in the Pacific halibut longline fleet operating off the state of Alaska. The project was conducted on two of the IPHC stock assessment survey vessels fishing in Alaska during 2002. The objectives of the project were to: 1) examine the ability of an electronic monitoring system to provide images that would allow an analyst to monitor seabird avoidance devices for regulatory compliance; 2) determine the feasibility of using video images for detecting and identifying incidentally-caught seabirds; and 3) discuss options for the future use of electronic monitoring as a fishery management tool.
    To determine if EMS could be used to assist in compliance determination, an EMS system was installed on two halibut longline vessels chartered by the IPHC. Cameras were placed on the stern and recorded images of halibut gear being set and the performance of seabird avoidance devices, or streamer lines, during the setting. Vessel and video observations were compared on 106 setting events. The video observations determined that the EMS was successful in detecting streamer line deployment and relative position on 100% of the daytime sets when two setting cameras were operating together. The results of the streamer line performance evaluations suggest that accurate performance recognition was positively related to the increase in image recording speed and the video analysts’ ability to distinguish measured interval markings that were attached to the streamer lines.
    The ability of a video analyst to recognize and identify the species of retrieved seabirds was examined by intentionally setting previously-caught frozen seabirds on the fishing gear. No birds were caught incidentally during this study. The results indicated that correct seabird identification is related both to the analyst’s knowledge of distinguishing species characteristics, and to the size of the seabird.
    In conclusion, this study indicates that an EMS monitoring program would produce accurate data and enable compliance evaluations for seabird avoidance devices. In addition, an EMS program would be able to detect a high proportion of incidentally caught seabirds. However, additional work is needed on seabird image identification and verification methods and testing the effects of soak time on the physical characteristics of seabirds.