University of Tasmania

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The relative safety of the Agreement on the Conservation of Albatrosses and Petrels (ACAP) recommended minimum specifications for the weighting of branchlines during simulated fly-backs

posted on 2023-05-25, 06:41 authored by McCormack, E, Nicholas Rawlinson
A reduction in the incidental capture of seabirds in pelagic longline fisheries can be achieved using weighted branchlines. However, weights on branchlines have resulted in ‘fly-backs’ during hauling that have caused serious injuries and deaths to fishers. We compared the relative safety of 3 current and 3 proposed minimum specifications of branchline weighting configurations that are recommended by the Agreement on the Conservation of Albatrosses and Petrels (ACAP) by simulating fly-backs and predicting the impact injury to the head and chest using the Blunt Trauma Criterion. We tested three different sizes (45 g, 60 g and 100 g) of weighted swivels and two different sizes of two brands of sliding leads, GloLeads (40 g and 60 g) and Lumo Leads (45 g and 60 g) that were positioned at different distances from the end of the branchline. Twelve metre monofilament branchlines were placed under 80 kg of tension and then cut to simulate a fly-back. Ten replicates of seventeen different branchline configurations were tested in this study. High speed videography was used to track the movement and velocity of the weights prior to impact with a backboard. The position of impact of each weight was also measured. One-hundred and twelve replicates resulted in in potentially dangerous fly-backs and 58 were classified as safe. Safety was strongly influenced by the type of weights used and their distance from the hook. Within the experimental conditions used, we conclude that sliding leads placed within 1 m of the hook or less will slide off the branchline and can be considered safe. However, branchline configurations with weighted swivels at any distance from the hook and sliding leads placed 2 m or more from the hook that do not slide off the end of the branchline can be considered potentially dangerous. All potentially dangerous fly-backs are predicted to result in more than a 50% chance of a skull fracture or a thoracic skeletal injury if the head or chest is hit by one of the weights. Under the conditions used to simulate fly-backs in this study, the current ACAP specification of greater than 45 g within 1 m of the hook, and the proposed specifications of greater than 40 g at the hook and greater than 60 g within 1 m of hook can be considered safe, but only if sliding leads are used.


Commissioning body

Agreement on the Conservation of Albatrosses and Petrels (ACAP)


v1, 15/F/04




Australian Maritime College


Agreement on the Conservation of Albatrosses and Petrels (ACAP)

Place of publication

Hobart, Tasmania

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  • Restricted

Socio-economic Objectives

Other environmental management not elsewhere classified

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