Bird Scaring Lines Protect Seabirds |
Bird-scaring lines have been shown to be highly effective in preventing seabird mortality caused by longlines. The erratic flapping made by the streamers that hang from the 300 ft. blue steel polyester lines, positioned either side of the longline, scares albatrosses and other seabirds from the baited hooks. These lines cost as little as $260 per pair and have been shown to reduce seabird mortality by 92% in preliminary research on Alaskan sablefish longliners in 1999. In 2000 the U.S. Fish and Wildlife Service initiated a pilot scheme by which Alaskan fishing vessels could apply for free bird-scaring lines. $950,000 was made available for Alaskan vessels that applied in 2000 and 2001. Much of this money was in the form of matching grants to cover the installation of davits that must be welded onto the stern of the larger longline vessels to hold the 'tori poles' that support the bird scaring lines.
Image courtesy Seattle Marine.
Another simple mitigation method is greater line weight. Lines sink because weights are placed on the line at intervals between the hooks. Increasing the number or size of these weights causes the line to sink faster, giving the birds less time to dive on the baited hook. Once the bait is more than a few feet under the surface it is no longer a threat to seabirds.
Fish waste is often thrown overboard, acting as a further attractant to seabirds. Unable to tell waste from bait, seabirds are more likely to be hooked if waste is thrown overboard while lines are being set. Disposing of fish waste only at times when lines are not being set reduces seabird mortality.
Instead of reeling the longline out from the stern of the vessel, a technique has been developed whereby the line is fed through a setting tube that is submerged under the surface. By the time the line comes out the end of the tube it is already too far under water for the albatrosses to be able to dive on the bait. This method has been shown to be very effective in the Southern Ocean.