Longline gear is comprised of groundline, buoy lines and gangions, which are short pieces of line with hooks on the end. These lines have baited hooks a few yards apart that sit along the bottom of the seabed. Particular bait along with certain fishing grounds are fished to target the specific specie(s) that the fishermen want to catch. The fishermen can unhook other unwanted species of fish and return them alive to the sea without bringing them on board. This is what makes longlining a sustainable method of fishing without catching much bycatch.
Pot fishing consists of large steel-framed cages covered in net mesh. The baited pots are placed on the seafloor where they trap black cod or cod. Fish enter the traps through tunnels but cannot escape. The pots are retrieved and the seafood is sorted on deck. Non-targeted species are then returned alive to the sea. This form of fishing is very sustainable without catching much bycatch. A varying type of pot and bait is also traditionally used for catching species of crab.
Trawlers use bag shaped nets that are towed below the surface of the water and can catch a number of marine species based on the depth they are fishing. There are regulations with regards to the amount of bycatch that a trawler can catch and keep since the non-targeted species are sorted onboard and kept. This method of fishing isn’t considered sustainable and makes it harder for fishermen to target specific species such as black cod without catching other fish.