- Shark repellent
A shark repellent is any method of driving sharks away from an area, object, person, or animal. Shark repellents are one category of
Shark repellents have been of interest to human beings for many years, for a number of reasons. Food fish caught by fishermen are also prey of many sharks, and a net filled with such fish can be very attractive to sharks in the area. Sharks themselves are sometimes caught inadvertently by fishermen. Sharks sometimes bite expensive underwater equipment such as cables, damaging or destroying it. Finally, shark repellents can be used to protect sharks by driving them away from areas where they are likely to be killed by human beings; in this case, the shark repellent serves as a conservation method.
For all of these reasons, shark repellents have attracted interest for as long as people and sharks have been encountering each other.
Current shark repellent technologies include
Magnetic shark repellent, Electropositive shark repellents, electrical repellents, and semiochemicals.
Some of the earliest serious 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, both real and imagined. 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 principles in dead shark bodies that repelled other sharks. Eventually, it was determined that certain copper compounds, such as copper sulfateand copper acetate, in combination with other ingredients, could mimic a dead shark and drive live sharks away from human beings in the water. For years, a combination of copper acetate and dye was supplied to sailors as a shark repellent.
Unfortunately, subsequent research revealed that the protection offered by these compounds was mostly an illusion. They were not nearly as effective as they had been made out to be.
Today, the search for an ideal shark repellent is still ongoing. Some research, based on
semiochemicals, looks promising. Electrical devices that disturb a shark's delicate lateral linesystem also seem to be at least partially effective. But the goal of the perfect shark repellent still remains elusive.
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shark repellent — noun a measure undertaken by a corporation to discourage unwanted takeover attempts • Syn: ↑porcupine provision • Hypernyms: ↑measure, ↑step • Hyponyms: ↑golden parachute, ↑greenmail, ↑ … Useful english dictionary
shark repellent — n. something that prevents corporate takeovers. (Securities markets.) □ Acme Systems tried again to get its board to approve a shark repellent to keep the Widget cartel from acquiring it. □ The shark repellent wasn’t enough … Dictionary of American slang and colloquial expressions
shark repellent — Gen Mgt provisions in a company’s bylaws that make it more difficult for a proposition such as a change of status or the acceptance of a hostile takeover bid to succeed. Elements of shark repellent may include: requiring a vote that is… … The ultimate business dictionary
shark repellent — noun Date: 1977 any of various measures that a company uses to fend off unwanted takeover attempts … New Collegiate Dictionary
shark repellent — 1) a chemical compound that discourages sharks from attacking humans 2) a measure undertaken by a corporation to discourage unwanted takeover attempts … Dictionary of ichthyology
shark repellent — any tactic used by a corporation to prevent a takeover by a corporate raider. [1980 85] * * * … Universalium
shark repellent — methods used by company management to ward off attempts at a hostile takeover (Finance) … English contemporary dictionary