Recommended seabird bycatch research priorities for tuna fisheries operating on the high seas
Recommendation 1. ACAP encourage a suitable organisation or organisations to conduct a survey of the potential misuse of bait casting machines used on tuna vessels operating on the high seas and report the findings to a future meeting of the SBWG. Misuse pertains to the distance baits are landed outboard of vessels, with landing distances outboard of the streamer line (if in use) position considered dangerous to seabirds. The survey could include the manufactures of bait casting machines and port-based inspection and trialling of machines on vessels. Power output settings and actual bait landing distances from vessels could be the main parameters quantified in the survey.
Recommendation 2. ACAP encourage a collaborative research program between relevant research organisations and a high seas tuna fishing nation to develop and test experimentally a new line weighting regime with greatly improve bait sink rates in surface depths (0-2 m) of the water column. The sink rate of the regime should approximate those promoted by ACAP as best practice. A target mean sink rate of 0.45 m/s to 2 m depth is suggested or 0.4 m/s if the faster rates is deemed technically infeasible. The aim of the experiment is to demonstrate that improved branch line weighting (and sink rates) significantly reduces seabird mortality without affecting fish catch, and therefore safeguards against any non-compliance to streamer line use on unobserved vessels operating on the high seas.