Longlines

Longlines are a type of fishing gear consisting of a main line from which numerous shorter branch lines, or snoods, hang at intervals. Each snood bears a baited hook. A longline can extend for kilometers and carry hundreds to thousands of hooks. The gear can be set on the surface or near the bottom and may be deployed by drifting or anchoring. The main line is buoyed with floats and weighted to control depth. Common baits include squid and small fish; hooks are often circle hooks to reduce bycatch.

Longlines target pelagic species such as tuna, swordfish, and marlin, as well as bottom-dwelling species like halibut and sablefish in some regions. Variants include surface longlines and bottom longlines; deep-set longlines are used in deeper waters. The technique is valued for efficiency and high catch potential.

Environmental concerns include bycatch of seabirds, sharks, turtles, and other non-target species, and the risk of ghost gear if lines are lost. Mitigation measures include night setting to reduce seabird interactions, weighted lines to submerge hooks, and gear modifications. Regulations vary by country and region and may cover line length, gear configuration, bycatch mitigation devices, and reporting requirements.

History: longlines emerged in the 20th century as a scalable method for pelagic fishing and are now widely used, though they remain controversial due to environmental impact.