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Summary
The use of line weighting to rapidly sink baited hooks under the protection of a tori line is recognised as an effective mitigation measure to reduce the bycatch of seabirds during the deployment of pelagic longlines.
Time depth recorders (TDRs) were used to compare sink profiles of heavy hooks and hook shielding devices to established best practice line weighting configurations. Tests were conducted both from a stationary vessel and during fishing operations. Sink times to depth were slower and more variable under real-world fishing conditions than under controlled conditions.
Both 60 g and 50 g heavy hooks sank with similar profiles to the current ACAP best practice line weighting recommendations of 60 g at a metre from the hook or 40 g at half a metre. The size and density of hook shielding devices reduced sink times, particularly under fishing conditions, indicating that the bulk of devices added to branchlines should be considered.
Publication information
Goad, D.; Schweder-Goad, C. 2025. Assessment of weighted hooks as a seabird bycatch mitigation option for surface longline fisheries. MIT2024-03. Final Report prepared by Vita Maris 9 p.