User:Thambley
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Drum lines
[edit]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.[1]
Trumpet lines
[edit]Description
[edit]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 polyurethane foam, which both helps it float, and fills it to keep it from being stolen out of the water for storage.[2] 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. [3]
Advantages
[edit]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.[4] Drum Lines physically attract sharks with its bait while the shark nets allow the sharks to swim over or around it. [5] Shark nets have a large amount of bycatch including: Dugongs, Dolphins, Sea Turtles and several harmless species of sharks.[6]. 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.
Disadvantages
[edit]Shark attacks themselves are extremely rare compared to other types of deaths, between 2004 and 2008 there has only been an average of 4 recorded shark attacks per year.[7] Each year more people are killed by having a coconut fall on their head than a shark. [8] Up to 73 million sharks are killed every year due to no commercial fishing limits on the sharks and their expensive fins.[9]Depending on their size only a few sharks survive being caught on a drum line. The combination of drum lines and shark nets do not directly lead to extinction, but they also do not give the population room to recover from being endangered of extinction.[10]
References
[edit]- ^ Richard Shears Great White Shark attacked Retrieved on 1-22-09
- ^ Dudley, Haestier, Cox, MurrayShark control: experimental fishing with baited drumlines Retrieved on 1-22-09
- ^ NATAL SHARKS BOARDDrumlines Frequently Asked QuestionsRetrieved on 1-22-09
- ^ Dudley, Haestier, Cox, MurrayShark control: experimental fishing with baited drumlines Retrieved on 1-22-10
- ^ Marine Science TodayAustralian Shark Control Programs Indiscriminately Catch Marine Life Retrieved 2-10-10
- ^ Remove Shark Nets Focus on Removing Australian Shark Nets Retrieved on 1-22-10
- ^ Icthyology ISAF Statistics for the Top Ten Worldwide Locations with the Highest Shark Attack Activity Since 1990 Retrieved on 2-9-10
- ^ Oceana Beach activities with higher fatality rates than shark attacks Retrieved on 2-10-10
- ^ Larry O'HanlonSaving The Sharks That Bit Us Retrieved 2-10-10
- ^ Remove Shark Nets Do the nets and drumlines really have a measurable impact on shark populations? Retrieved 2-10-10
