Longline sink rates of an autoline vessel, and notes on seabird interactions

Published source details Smith N.W.M. (2001) Longline sink rates of an autoline vessel, and notes on seabird interactions. Science for Conservation, 183, 5-32.
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This study is summarised as evidence for the following.

	Action	Category
	Weight baits or lines to reduce longline bycatch of seabirds Action Link
	Use streamer lines to reduce seabird bycatch on longlines Action Link

Weight baits or lines to reduce longline bycatch of seabirds

A study on a longlining vessel on the Chatham Rise, New Zealand, in July-August 1998 (Smith 2001) and using weighted lines and a streamer line (see ‘Use streamer lines to reduce seabird bycatch on longlines’), caught an average of 0.0093 birds/1,000 hooks – far lower than many other studies. Weights of 5 kg were attached every 400 m, but only caused faster sinking for approximately 40 m either side.
Use streamer lines to reduce seabird bycatch on longlines

A study on a longlining vessel on the Chatham Rise, New Zealand, in July-August 1998 (Smith 2001) and using weighted lines (see ‘Weight baits or lines to reduce longline bycatch of seabirds’) and a streamer line caught an average of 0.0093 birds/1,000 hooks – far lower than many other studies. The streamer line extended 75-85 m behind the boat, covering the longline to a depth of 2-5 m. Many seabirds can dive up to 10 m (a depth not reached until 170 m behind the streamer), so the authors caution that the streamer may not offer as high protection as it appeared.