Deep Set Long-Lines

Deep Set Long-Lines

The deep set longline fisheries are closely monitored by the National Oceanic and Atmospheric Administration (NOAA) and have 100% observer coverage. This means a fisheries biologist travels onboard the vessel, on every trip and collects biological data about each species caught. Collectively this data and the presence of the observer, ensures that the health of each species is closely monitored and that sensitive bycatch species are documented and released. 

Traditional long-line fishing gear has a poor reputation for a few important reasons. The gear is set relatively shallow in the water column, above the thermocline, where sensitive unintended species are caught, better known as by-catch. One of the reasons these bycatch species often don’t survive is because the gear is left unattended over many miles. Furthermore, the long distance of gear used, and the high number of hooks make it so the gear is at greater risk of being lost or snapped off altogether potentially causing even greater harm.  

The deep-set longline method was modified from the longline fishery. Extensive research revealed that the vast majority of the sensitive by-catch species inhabited shallower, warmer waters. To adapt, the gear was modified with weights to be brought down below the thermocline, the waters where the target species mainly inhabit. Then the gear distance was shortened and the amount of hooks and hook type (circle) was regulated to make it easier to release by-catch species if caught. These modifications have improved the fishery greatly, along with the tight monitoring and brought it to a level that we feel comfortable supporting. Below is a diagram showing how the gear is fished as well as helpful links if you’re interested in learning more. 

Links & Works Cited


West Coast Observer Program. NOAA. 9/14/2020. National Oceanic and Atmospheric Administration. Department of Commerce.  


Monterey Bay Aquarium Seafood Watch Program. Opah Recommendation. March 1, 2021


Bycatch Management Observation System.


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