Drum lines
Encyclopedia
A drum line is an aquatic device used to reduce the amount of shark attacks in popular beaches by capturing the shark on the drum line's hook. While most drum lines are used in addition to the shark net
, it has been proven that the drum line is more effective at catching the three more deadly sharks. A shark net is a net that is left submerged underwater in order to capture potentially harmful sharks. The combination of drum lines and shark nets have been proven to be successful in reducing shark attacks in the areas protected by them. Since the shark nets and drum lines have been put into use, there has only been one death caused by a shark attack on a protected beach.
foam, which both helps it float, and fills it to keep it from being stolen out of the water for storage. In order to attract sharks, the hooks are baited with red mullet
and false jacopever. Since the objective of the drum line is to get sharks away from popular beaches, not to attract the sharks to the beaches, only about 500 grams of bait are added to each hook to reduce the attraction of sharks. The sharks can only sense these baits from a couple hundred meters away.
The Drum Lines first started to come into use in Queensland Australia in 1962. During this time they were just as successful in reducing the frequency of shark attacks as the shark nets on the beaches in New South Wales and KwaZulu-Natal. While shark nets and drum lines share the same purpose, drum lines are more effective at targeting the three sharks that are more dangerous to swimmers. Those three sharks are the bull shark
, tiger shark
and great white shark
. Drum Lines physically attract sharks with its bait while the shark nets allow the sharks to swim over or around it. Shark nets have a large amount of bycatch including: Dugongs, Dolphins, Sea Turtles and several harmless species of sharks. The bycatch
, or unintended catches, of the drum lines are a lot less likely than those of the shark nets.The drum lines are more effective because they reduce the amount of shark attacks just as effectively as shark nets, with a major reduction in bycatch.
Shark net
A shark net is a submerged net placed around beaches to reduce shark attacks on swimmers.Shark nets do not offer complete protection but work on the principle of "fewer sharks, fewer attacks". They reduce occurrence via shark mortality. Reducing the local shark populations is believed to reduce the...
, it has been proven that the drum line is more effective at catching the three more deadly sharks. A shark net is a net that is left submerged underwater in order to capture potentially harmful sharks. The combination of drum lines and shark nets have been proven to be successful in reducing shark attacks in the areas protected by them. Since the shark nets and drum lines have been put into use, there has only been one death caused by a shark attack on a protected beach.
Description
The drum line consists of a drum, with two lines attached to it, one line is attached to an anchor going to the sea floor, the other has a baited shark hook. In order to keep people from stealing the drum, it is filled with a rigid polyurethanePolyurethane
A polyurethane is any polymer composed of a chain of organic units joined by carbamate links. Polyurethane polymers are formed through step-growth polymerization, by reacting a monomer with another monomer in the presence of a catalyst.Polyurethanes are...
foam, which both helps it float, and fills it to keep it from being stolen out of the water for storage. In order to attract sharks, the hooks are baited with red mullet
Red mullet
The red mullets or surmullets are two species of goatfish, Mullus barbatus and Mullus surmuletus, found in the Mediterranean Sea, east North Atlantic Ocean, and the Black Sea. Both "red mullet" and "surmullet" can also refer to the Mullidae in general.Though they can easily be distinguished—M...
and false jacopever. Since the objective of the drum line is to get sharks away from popular beaches, not to attract the sharks to the beaches, only about 500 grams of bait are added to each hook to reduce the attraction of sharks. The sharks can only sense these baits from a couple hundred meters away.
Advantages
The Drum Lines first started to come into use in Queensland Australia in 1962. During this time they were just as successful in reducing the frequency of shark attacks as the shark nets on the beaches in New South Wales and KwaZulu-Natal. While shark nets and drum lines share the same purpose, drum lines are more effective at targeting the three sharks that are more dangerous to swimmers. Those three sharks are the bull shark
Bull shark
The bull shark, Carcharhinus leucas, also known as Zambezi shark or unofficially known as Zambi in Africa and Nicaragua shark in Nicaragua, is a shark common worldwide in warm, shallow waters along coasts and in rivers...
, tiger shark
Tiger shark
The tiger sharks, Galeocerdo cuvier, is a species of requiem shark and the only member of the genus Galeocerdo. Commonly known as sea tigers, tiger sharks are relatively large macropredators, capable of attaining a length of over . It is found in many tropical and temperate waters, and is...
and great white shark
Great white shark
The great white shark, scientific name Carcharodon carcharias, also known as the great white, white pointer, white shark, or white death, is a large lamniform shark found in coastal surface waters in all major oceans. It is known for its size, with the largest individuals known to have approached...
. Drum Lines physically attract sharks with its bait while the shark nets allow the sharks to swim over or around it. Shark nets have a large amount of bycatch including: Dugongs, Dolphins, Sea Turtles and several harmless species of sharks. The bycatch
Bycatch
The term “bycatch” is usually used for fish caught unintentionally in a fishery while intending to catch other fish. It may however also indicate untargeted catch in other forms of animal harvesting or collecting...
, or unintended catches, of the drum lines are a lot less likely than those of the shark nets.The drum lines are more effective because they reduce the amount of shark attacks just as effectively as shark nets, with a major reduction in bycatch.