Seabird avoidance measures for small Alaskan longline vessels

Given the lack of information on appropriate seabird avoidance measures for small Alaskan longline vessels, we determined the “2-m access window”, or the distance astern that longline hooks were accessible to surface foraging Alaska seabirds, for 8 fishing vessels > 7.9 m to 16.8 m (> 26 to 55 feet) using two gear types: snap-on gear and fixed gear. We also determined the capability of these vessels to deploy streamer lines and/or buoy lines according to performance standard guidelines. Vessel speed was found to be a primary determinant of both the distance astern that longline hooks were accessible to surface foraging seabirds, and the performance standards of streamer lines. Vessels deploying snap-on gear at 2 to 3.5 knots produced mean access windows of 28 to 38 m while the mean access window produced by vessels deploying fixed gear at faster speeds averaged 90 m. Gear sink rates among vessels and gear types were similar (0.09 to 0.13 for snap on gear vessels and 0.07 m/s for fixed gear). We determined that the current single streamer line requirement for snap-on gear vessels over 16.8 m and with infrastructure (a 45-m streamer line with a minimum aerial distance of 20 m) was achievable and practical regardless of vessel size, especially with a lighter streamer line design. However, the current requirement for small vessels using fixed gear of a single streamer line with no mandatory material or performance standards is unlikely to provide sufficient protection to seabirds. Specific recommendations for seabird avoidance requirements are proposed for these small vessels based on these results.