Categorising branch line weighting for pelagic longline fishing according to sink rates

Citation
Barrington J, Robertson G, Candy SG (2016) Categorising branch line weighting for pelagic longline fishing according to sink rates. In: ACAP - Seventh Meeting of the Seabird Bycatch Working Group. ACAP-SBWG7-Doc7, Serena, Chile
Abstract

Statistical analysis is provided supporting categorisation of branch line weighting for pelagic longline fishing according to sink rates. New information is provided about sink rates of differing branch line weighting configurations including assigning weighting configurations into statistically significant categories. The analysis completes step one of the re-evaluation of branch line weighting configurations for pelagic longline fishing under the three-step research programme endorsed by the Advisory Committee at its eighth meeting (Punta del Este, Uruguay, 15-19 September 2014). The analysis provides further support for adopting short leaders as best practice branch line weighting for pelagic longline fishing. RECOMMENDATIONS 1. That SBWG recognises categorisation of branch line weighting for pelagic longline fishing according to sink rates is supported by statistical analysis. 2. That SBWG notes statistical analysis strengthens the proposal to amend ACAP’s summary advice for reducing impact of pelagic longlines on seabirds to replace existing advice concerning branch line weighting with the following: - 40 g or greater attached at the hook; or - 60 g or greater attached within 1 m of the hook; or - 80 g or greater attached within 2 m of the hook. Positioning weight farther from the hook is not recommended. 3. That SBWG also notes these weighting regimes safeguard against any non- compliance to the use of bird scaring lines and night setting, due to much faster sink rates than regimes recommended by ACAP. 4. That SBWG recommends core funding from the Advisory Committee budgetary appropriation be allocated to support research concerning step three of the three-step research programme.