Bird-scaring line designs for small longline vessels

Citation
Goad D, Debski I (2017) Bird-scaring line designs for small longline vessels. In: ACAP - Eighth Meeting of the Seabird Bycatch Working Group. SBWG8-Doc-12, Wellington, New Zealand
Abstract

Bird-scaring lines are one of the most thoroughly tested seabird bycatch reduction measures available, and have been proven effective in reducing seabird bycatch in longline fisheries. However, most of the work to date has been carried out on vessels over 20 m in length and achieving ACAP best practice minimum standards for bird-scaring lines in small vessels has proven difficult. The development of bird-scaring line configurations for small vessels was recognised as a mitigation research priority at SBWG7. This report builds on initial work presented at SBWG7 on the development of bird-scaring line configurations suited to small vessel (approximately 12-25 m in length) operating in New Zealand’s pelagic and demersal longline fisheries. We have further refined the bird-scaring line designs so that they are suitable for use under fishing conditions, addressed the concerns raised by fishers, and tested the lines during commercial fishing activity. The configurations developed and tested aimed to be as close as possible to ACAP best practice advice, achieving maximum aerial extent feasible, whilst still allowing for safe, achievable and practical deployment and operation. Our results found that the use of bird-scaring lines with an aerial extent of 75 m was achievable on small pelagic, and some demersal, longline vessels using a modified long streamer configuration. We have provided detailed suggestions on materials and configurations to achieve this aerial extent, and make recommendations for ACAP best practice advice to be modified for small longline vessels to reflect a number of small vessel operational factors may influence minimum requirements for the streamer configuration, attachment height, drag section, length of bird-scaring line and tension release.

RECOMMENDATIONS We recommend that the Working Group: 1. Review ACAP best practice mitigation advice on bird scaring lines for pelagic longline fisheries, in particular the minimum specifications and notes related to streamer configuration, attachment height, drag section and tension release, to reflect operational requirements of small vessels (approx. 12-25 m in length). 2. Review ACAP best practice mitigation advice on bird scaring lines for demersal longline fisheries, in particular the minimum specifications and notes related to streamer configuration, attachment height, total length, drag section and tension release, to reflect operational requirements of small vessels (approx. 12-25 m in length). 2. Review ACAP best practice mitigation advice on bird scaring lines for demersal longline fisheries, in particular the minimum specifications and notes related to streamer configuration, attachment height, total length, drag section and tension release, to reflect operational requirements of small vessels (approx. 12-25 m in length). 2. Review ACAP best practice mitigation advice on bird scaring lines for demersal longline fisheries, in particular the minimum specifications and notes related to streamer configuration, attachment height, total length, drag section and tension release, to reflect operational requirements of small vessels (approx. 12-25 m in length).