Longlines can operate at various depths depending on the targeted species and the type of longlining method used: Surface/Pelagic Longlines: These are set near the surface, typically targeting pelagic species like tuna, swordfish, and mahi-mahi. The depths can range from just below the surface to about 100 meters deep. Mid-water Longlines: Targeting species that inhabit the middle layers of the ocean, these lines can be set at depths ranging from around 100 meters to 500 meters. Bottom/Deep-set Longlines: These target demersal or bottom-dwelling species such as snappers, groupers, halibut, and certain sharks. They can operate at depths from about 200 meters to over 1,500 meters, and in some cases, even deeper, depending on the specific fishing grounds.