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What’s the Catch? Examining Optimal Longline Fishing Gear Configurations To Minimize Negative Impacts on Non-Target Species

September 01, 2022

We investigate potential options to optimize fishing gear configurations for United States Pacific pelagic longline vessels to maintain target catch rates whilst reducing bycatch mortality, injury, and harm.

Changes to fishing gear configurations have great potential to decrease fishing interactions, minimize injury and reduce mortality for non-target species in commercial fisheries.

In part one, a paired-gear trial was conducted on a deep-set tuna longline vessel to compare catch rates and catch condition of target and non-target species between wire and monofilament leader materials. Temperature-depth recorders were also deployed on hooks to determine sinking rates and fishing depth between the two leader materials.

In part two, hooks of different configurations (size, diameter, shape, metal type, and leader material) were soaked in a seawater flume for 360 days to obtain quantitative estimates of breaking strength, as well as the time taken for gear to break apart.

 These results have direct implications for fisheries management and the operational effectiveness of bycatch mitigation strategies for longline fisheries worldwide.


Scott M, Cardona E, Scidmore-Rossing K, Royer M, Stahl J, Hutchinson M. 2022. What's the catch? Examining optimal longline fishing gear configurations to minimize negative impacts on non-target species. Marine Policy. Volume 143.  https://doi.org/10.1016/j.marpol.2022.105186.

Last updated by Pacific Islands Fisheries Science Center on 10/12/2022

Longline