Shark repellent

For the business strategy, see Poison pill.

A shark repellent is any method of driving sharks away from an area. Shark repellents are a category of animal repellents. Shark repellent technologies include magnetic shark repellent, electropositive shark repellents, electrical repellents, and semiochemicals.

Shark repellents can be used to protect people from sharks by driving the sharks away from areas where they are likely to kill human beings. In other applications, they can be used to keep sharks away from areas they may be a danger to themselves due to human activity. In this case, the shark repellent serves as a shark conservation method.

There is evidence that surfactants such as sodium lauryl sulfate can act as a shark repellent at concentrations on the order of 100 parts per million. However, this does not meet the desired "cloud" deterrence level of 0.1 parts per million.[1][2]

Research indicates that sharks will avoid an area when they smell chemical released by dead and dying sharks. Six chemicals were synthesized from shark glands and tissues and used in experiments. Sharks immediately reacted once they detected these chemicals. To quote a 2004 Associated Press article, "Fisherman and scientists have long noted sharks stay away if they smell a dead shark."[3] This effect was dramatically demonstrated in a MythBusters episode in which Adam Savage and Jamie Hyneman were able to drive away 10-20 Caribbean reef sharks and nurse sharks in only a few seconds on two separate occasions. The repellent used consisted of extracts from other species of shark bodies, and sharks did not return for over 5 minutes on both occasions.[4]

History

Some of the earliest research on shark repellents took place during the Second World War when military services sought to minimize the risk to stranded aviators and sailors in the water. Studies at the time, combined with historical research, revealed that about the only thing that will drive sharks away is the odor of another dead shark. Efforts were made to isolate the active components in dead shark bodies that repelled other sharks. Eventually, it was determined that certain copper compounds like copper acetate,[5] in combination with other ingredients, could mimic a dead shark and drive live sharks away from human beings in the water.

Building on this work, Stewart Springer and others patented a "shark repellent" consisting of a combination of copper acetate and a dark-colored dye to obscure the user.[6] This shark repellent, known as "Shark Chaser," was long supplied to sailors and aviators of the United States Navy, initially packaged in cake form using a water-soluble wax binder and rigged to life vests. The Navy employed Shark Chaser extensively between 1943 and 1973. It is believed[5] that the composition does repel sharks in some situations, but not in all, with about a 70% effectiveness rating.

On the other hand, Albert Tester questioned the idea that dead shark bodies or chemicals based on them could work as shark repellent. In 1959, he prepared and tested extracts of decaying shark flesh on tiger sharks in Hawaii and blacktip sharks at Enewetak Atoll. Tester found that not only did the dead shark extracts fail to repel any sharks, but several sharks had a "weak or strong attraction" to them. Tester reported a similar failure to repel sharks by a 1959 test at Enewetak of "an alleged shark repellent, supplied by a fisherman, which contained extract of decayed shark flesh as the principle component."[7]

There have been validated field tests and studies to confirm the effectiveness of semiochemicals as a shark repellent. From 2005-2010, an extensive study on the effectiveness of semiochemicals as a shark repellent was conducted by scientists from SharkDefense Technologies and Seton Hall University. The studies results were published in the scientific journal Ocean & Coastal Management in 2013. The study concluded that the existence of a putative chemical shark repellent has been confirmed.[8]

As of 2014, SharkDefense partnered with SharkTec to manufacture the semiochemical in a cansister as a shark repellent for consumers.

Recently, SharkDefense used the same semiochemicals found in SharkTec's product to reduce shark by-catch by 71% in a government grant initiative. The government agency NOAA released these findings in a report to Congress.[9]

References

  1. ↑ Smith, Larry J. (1991). "The effectiveness of sodium lauryl sulphate as a shark repellent in a laboratory test situation". Journal of Fish Biology. 38: 105. doi:10.1111/j.1095-8649.1991.tb03096.x.
  2. ↑ Sisneros, Joseph A.; Nelson, Donald R. (2001). "Surfactants as Chemical Shark Repellents: Past, Present, and Future". Environmental Biology of Fishes. 60: 117. doi:10.1023/A:1007612002903.
  3. ↑ Researchers tout shark repellent
  4. ↑ Hyneman, James F.; Savage, Adam W. (August 29, 2015). "Dead Shark Repellent MiniMyth". Discovery.com. Discovery Communications. Retrieved September 25, 2016.
  5. 1 2 Thomas B. Allen. Shadows in the Sea: The Sharks, Skates and Rays
  6. ↑ US 2458540, Brinnick, Frederic E.; John M. Fogelberg & Horace Stewart Springer et al., "Shark repellent", issued 1949
  7. ↑ Tester, Albert L. (April 1963). "The role of olfaction in shark predation". Pacific Science. 17 (2): 145–170. hdl:10125/4935. ISSN 0030-8870. Retrieved September 25, 2016.
  8. ↑ http://bmis.wcpfc.int/docs/references/Stroud_etal_2013_Chemical_shark_repellent_Myth_fact_necromones_effect_OpenA.pdf
  9. ↑ Stroud, Eric (October 2014). "Performance of a long lasting shark repellent bait for elasmobranch bycatch reduction during commercial pelagic longline fishing" (PDF). National Oceanic and Atmospheric Administration.
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