In South Australia, fish traps are used to catch finfish species that live on or near the sea floor. They are generally used in deeper water and target Ocean Jackets (a type of leather jacket), as well as other species such as nannygai, and sometimes snapper.
Fish traps are weighted at the bottom so that when set they land on the sea floor the correct way up. Traps are baited so fish will be attracted to the scent of the bait and swim through the entrance. The traps are designed in a way so that the targeted species cannot escape once inside the trap. To ensure that juvenile and non-target fish are able to escape, fish traps have escape gaps of a minimum size.
When set, traps are connected to a downline which is attached to the trap at opposite ends. The downline is connected to a buoy on the surface which allows fishers to locate the traps. The size and specifications of traps used in South Australia are regulated to ensure that they do not harm the seabed ecosystem and minimise the catch of smaller fish.
Environmental impacts and management
Fish traps have a minimal impact on the marine environment, with low levels of bycatch and interactions with protected species being rare. Fish which have been caught in traps are often alive and in good health when they reach the surface, which greatly increases post capture survivability.
If a trap is lost, they disintegrate slowly over time and, in some areas, they are also fitted with a ‘sacrificial’ trapdoor that disintegrates quickly to allow trapped fish to escape.