A traditional commercial fishing technique, longline fishing uses a central fishing line that measures anywhere between 1 to 60 miles in length. The line has baited hooks at evenly spaced intervals, usually between 3 and 164 feet. When placed near the water's surface, longlines usually catch pelagic fish such as tuna and swordfish. To catch deep fish such as cod and halibut, lay the longline on the sea floor. The baits often attract other sea creatures such as sea turtles, seabirds and sharks. Since the 1970s, people have been using mechanised longline fishing systems.
Drop buoys and anchors to stop the boat at the fishing site.
Bait the hooks on the main fishing line and sink the line in the water. If using a mechanised fishing system, feed the bait into the baiting machine, which will automatically bait the hooks and set the line over the stern. Wait for fish to bite the bait.
Haul the line and set the fish aside. If using a mechanised system, a line hauler automatically pulls the line, removes the fish and cleans the hooks.
Use circle hooks rather than traditional J-shaped hooks to catch more fish and minimise unnecessary injury. Sinking the line deeper minimises the number of nontarget marine life caught.