Electronic monitoring of seabird interactions with trawl third-wire cables on trawl vessels – a pilot study

Archipelago Marine Research Ltd. Was selected by the Alaska Fisheries Science Center to test electronic monitoring (EM) equipment for possible use to examine seabird interactions with trawl third-wire cables on trawl vessels. This pilot study involved field testing of EM systems on shoreside delivery and head and gut bottom trawl vessels conducting operations in the Bering Sea, U.S. Exclusive Economic Zone. EM systems, consisting of two closed circuit television cameras, GPS, hydraulic and winch sensors, and on-board data storage, were deployed on five fishing vessels for 14 fishing trips during a one-month period in the fall of 2002. Detailed analysis of about 200 hours of fishing imagery occurred, representing 20 shoreside delivery vessel fishing events and 32 head and gut fleet fishing events. Results from the study demonstrated that EM could effectively monitor seabird interactions with trawl third-wire cables. The EM system provided imagery of sufficient quality to detect the presence, abundance, and general behaviour of seabirds during most daylight fishing events. As well, EM-based imagery was also able to detect third-wire entanglements of seabirds although it was not possible to determine the cause of these entanglements. EM imagery was not very useful for seabird enumeration and species identification. In regard to monitoring seabird interactions with trawl third-wires, EM would be suitable for monitoring the use and effectiveness of mitigation measures.