|
-- R e p e l l e n t s --
click on the question number for the answer |
||
| Q 1. | ||
| Is cupric acetate effective as a shark repellent, and if so, how is it used in underwater swimming? |
||
| Q 2. | ||
| Has an effective barracuda repellent been developed? |
||
| Q 3. | ||
| How do commercial fishermen combat sharks which damage their nets? |
||
| Q 4. | ||
| I would appreciate any information you can give me on a shark repellent. |
||
| Q 5. | ||
| In my attempt to find, chemically, a shark repellent to assist commercial fishermen, I have been using cupric acid, copper acetate and carbo wax in the ratio of 10 to 7. My question is, how toxic is that preparation? Do or will the fish caught in the nets absorb enough to be unfit for sale? Will the copper residue be absorbed in the fish gills or the body of the fish? |
||
| Q 6. | ||
| Is there a grease, or can one be developed, which when rubbed on the skin will repel sharks and piranha? |
||
| Q 7. | ||
| For the past few years I have been constantly plagued by sharks while fishing in the deep blue Gulf waters southeast of the mouth of the Mississippi River off the Louisiana coast. If the hooked fish is in the water any length of time, he becomes shark bait. I have tried the Navy shark repellent with little or no success. It is quite distressing to lose a beautiful blue marlin or tuna to a hungry shark. Could you send me some information on how I might effectively combat sharks while fishing? |
||
| Q 8. | ||
| What is the composition of the common shark repellent? Is it really effective in driving off or keeping away dangerous sharks? |
||
| Q 9. | ||
| We are fishing a fleet of twenty American flag vessels off the coast of Nicaragua, for shrimp. Our nets are being attacked by sharks when they are lifted. This is disastrous to us because aside from losing the nets, we are losing the catch of shrimp. Is any research being done regarding this problem and can you give us any help in this matter? |
||
| Q 10. | ||
| I am interested in any information on sound frequencies that will repel fish. My interest lies in finding a method of keeping fish away from salt-water swimming areas. |
||
| Q 11. | ||
| I have heard that sound waves of a particular frewuency will drive away sharks. Could you send me some detailed information? What kind of apparatus would be required to project sounds into the water? |
||
| Q 12. | ||
| I recently read about the Moses sole (Pardachirus marmoratus) and the shark-repelling fluid it secretes. If this fluid is so effective, why is it not being used to protect divers and swimmers? |
||
| Q 13. | ||
| Is it feasible to use dolphins to patrol beaches and chase away sharks? |
||
| Q 14. | ||
| On a television program, it was stated that sharks fear the banded sea snake and that some divers have painted their wet suits to resemble this animal to ward off shark attacks. Is a striped wet suit actually an effective shark repellent? |
||
| Q 15. | ||
| Has an effective means of preventing shark attacks been developed? |
||
| Q&A 1. | Is cupric acetate effective as a shark repellent, and if so, how is it used in underwater swimming? Fort Lauderdale, Florida |
||
| Cupric acetate has been found to be an effective shark repellent, but its low solubility in water makes a solution of it difficult to prepare. By placing cupric acetate in water and heating it, a solution of 20 parts by weight per 100 parts of water may be prepared. This is then poured over sawdust, and thE sawdust tied in a cheesecloth bag or flour sack which is carried along while swimming underwater. By mixing a small amount of fluorescent dye with the solution, the rate of diffusion underwater may be estimated. |
|||
| go back to Questions |
|||
| Q&A 2. | Has an effective barracuda repellent been developed? Fort Lauderdale, Florida |
||
| Despite the fact that cupric acetate has been reported to be a highly effective shark repellent, no repellent for barracuda has been developed as yet. Shark repellent is based on the physical qualities of decaying shark meat, which is itself a good shark repellent. Since the barracuda differs but little in its physiological makeup from ordinary predatory fish, it is unlikely that a special repellent could be manufactured that would work on barracuda alone. |
|||
| go back to Questions |
|||
| Q&A 3. | How do commercial fishermen combat sharks which damage their nets? Concord, New Hampshire |
||
| Many fishermen have used guns to kill off sharks in areas where they wished to fish, but this method has not been too successful. Harpooning has also been tried but is too time consuming a method to be effective. The Department of Fisheries in Canada has devised means of combating basking sharks which have become a growing menace to certain salmon fisheries along the British Columbia coast. They have fitted the bow of one of their vessels with a pointed steel ram, sharpened on the forward end and hinged so that it may be carried in a closed position when not in use. In operation the cutting edge of the ram is just beneath the surface of the water and faces upwards. When sharks are sighted the vessel is headed directly for the school and individuals are picked out and rammed. This action reduces the numbers of sharks and also tends to scatter the schools, making it more feasible for fishermen to operate their nets in the area. |
|||
| go back to Questions |
|||
| Q&A 4. | I would appreciate any information you can give me on a shark repellent. Naples, Florida |
||
| The shark repellent now being used by all the U.S. Armed Forces was prepared by the U.S. Navy in 1943. It is a combination of copper acetate and a nigrosine dye. It has been demonstrated by laboratory and field tests that copper acetate impedes feeding by sharks, presumably by action on the olfactory sense. The dye is supposed to envelope the swimmer in a black cloud, thus interfering with the visual sense of the shark. Sharks are believed to be sensitive to vibrations, however, and a swimmer's movements might enable the shark to perceive him in spite of the black cloud. Although this repellent is claimed to be effective, many cases have come to light in which there seemed to be no effect. A plan of research for the development of a better shark repellent and an extension of our knowledge of the behavior of sharks was outlined recently at a symposium in New Orleans. |
|||
| go back to Questions |
|||
| Q&A 5. | In my attempt to find, chemically, a shark repellent to assist commercial fishermen, I have been using cupric acid, copper acetate and carbo wax in the ratio of 10 to 7. My question is, how toxic is that preparation? Do or will the fish caught in the nets absorb enough to be unfit for sale? Will the copper residue be absorbed in the fish gills or the body of the fish? Fort Pierce, Florida |
||
| Very little is known about shark behaviour and the effects of various shark repellants. Current shark repellants have not been successful in general and as a result this problem and related problems are under intensive study. There is no attempt in designed shark repellants to kill or injure the shark, since this seems to be a rather hopeless task. Instead, shark repellants are designed to repel sharks either by visual means or by objectionable odors. Copper salts, of course, are toxic and sharks are sensitive to copper salts. In some of the larger aquaria the problem of retaining sharks for long periods of time where copper salts are used in water is a very real one. It is unlikely that copper salts used in small amounts in the ocean would be sufficiently concentrated to contaminate the fish or to repel the sharks. Intensive use of copper salts in bay areas might eliminate many other animals and plants from the area and contaminate food fishes. |
|||
| go back to Questions |
|||
| Q&A 6. | Is there a grease, or can one be developed, which when rubbed on the skin will repel sharks and piranha? Paramaibo, Surinam |
||
| There is no grease that is a repellant to sharks, although claims are made of the existence of such a substance. Even the Navy shark chaser is not completely effective. A national panel is reviewing the shark repellant problem at present and conducting studies which may lead to the development of a true shark repellant. There is no repellant for the piranha. Little is known of the biology of the various species of piranha, but no doubt they have preferred habitats. Fresh water fishes such as the piranha may be eradicated from small bodies of water by app1icatioD of various rotenone products. However, the use of such products would eliminate game and food fishes along with the trash fishes. |
|||
| go back to Questions |
|||
| Q&A 7. | For the past few years I have been constantly plagued by sharks while fishing in the deep blue Gulf waters southeast of the mouth of the Mississippi River off the Louisiana coast. If the hooked fish is in the water any length of time, he becomes shark bait. I have tried the Navy shark repellent with little or no success. It is quite distressing to lose a beautiful blue marlin or tuna to a hungry shark. Could you send me some information on how I might effectively combat sharks while fishing? Baton Rouge, Louisiana |
||
| At present there is no effective way to combat sharks. The area near the mouth of the Mississippi River is particularly shark-ridden, and the schools in this region plague anglers and commercial fishermen alike. The present Navy Shark repellent, as you state, is of almost no value. Long-range research at the University of Miami Institute of Marine Science (see Sea Frontiers, November, 1961) headed by Dr. Warren Wisby is probing the hearing and detection of vibration by sharks. Possibly a sonic repellent will be developed in the future to counter the attacks of sharks, using the basic scientific principles obtained from this study. 'The Game Fish Research Committee of the International Oceanographic Foundation is involved currently in a program to effect cooperation between anglers and marine scientists in solving problems and collecting data of mutual i interest. One of its projects, now in the planning stage, would enlist the cooperation of anglers in killing sharks on a wholesale basis. The Committee believes that if anglers were to devote part of their fishing effort to angling for or killing (for example, shooting) sharks each time they went fishing, they would be making a real contribution toward control of these marauders. It seems likely that until practical methods of wholesale destruction become available, the best method of combating sharks is to bait them using blood, bloody fish, chicken guts, etc. – or any shark attractant – and then kill them off as completely as possible. Experience has shown that, at least temporarily, sharks can be cleared out of a coastal area or estuary. But whether this will work for blue-water sharks is not yet known. Recently an expedition from the Institute of Marine Science, experienced success using this method off Panama. |
|||
| go back to Questions |
|||
| Q&A 8. | What is the composition of the common shark repellent? Is it really effective in driving off or keeping away dangerous sharks? Fond du Lac, Wisconsin |
||
| Shark repellents formerly were based upon the theory that sharks avoid regions of the sea bottom containing disintegrating shark carcasses. This folkway stemmed from the observation of commercial shark fishermen that when eviscerated shark carcasses are dumped in a previously fertile shark fishing ground at sea, sharks abandon the area and can no longer be taken there. This observation was followed by the assumption that something in the carcasses serves to repel living sharks from the region where mutilated bodies are deposited. A search was instituted to identify possible repellent compounds contained in decaying shark flesh. One of the early compounds discovered in sizeable concentration was acetic acid. Commercial shark repellents therefore were formulated to utilize large concentrations of a copper salt of this cheap compound, which was presumed to be the active repellent ingredient. During World War II most of the shark repellent packets built into the "Mae West" life jackets contained this material. Although the availability of this "shark repellent" undoubtedly provided considerable psychological solace to downed aviators, modem investigation makes it appear extremely unlikely that r this repellent had the slightest influence on any shark. The whole problem of formulation of suitable shark repellents is being actively investigated at present, but no final solution to the problem has yet appeared. |
|||
| go back to Questions |
|||
| Q&A 9. | We are fishing a fleet of twenty American flag vessels off the coast of Nicaragua, for shrimp. Our nets are being attacked by sharks when they are lifted. This is disastrous to us because aside from losing the nets, we are losing the catch of shrimp. Is any research being done regarding this problem and can you give us any help in this matter? Philadelphia, Pennsylvania |
||
| Your problem is one which has not been solved. There is no useful shark repellent. The one being used by the Navy is of more psychological help to the man in the water than of real effect in repelling sharks. We can only suggest that your men keep guns handy to shoot the sharks which attack their trawls. Work is going on at many laboratories on shark behavior, with the hope of finding how to keep them away from swimmers and fishing gear. Perhaps a letter to the U.S. Bureau of Commercial Fisheries, Pascagoula, Mississippi might bring some suggestions. |
|||
| go back to Questions |
|||
| Q&A 10. | I am interested in any information on sound frequencies that will repel fish. My interest lies in finding a method of keeping fish away from salt-water swimming areas. Taft, Texas |
||
| While a number of scientific studies have been concerned with determining what sounds will attract fishes, very few efforts have been made to repel fishes with sound. A few years ago the U.S. Bureau of Commercial Fisheries attempted to use sound in fresh water in an effort to prevent salmon from being destroyed in the turbines of a power generator at a dam in the state of Washington. Large steel plates, placed in the water parallel to the flow, were beaten rapidly by air hammers to produce sounds that could be heard by human ears at considerable distance. Results were negative, however. Although the fish were repelled at first, they soon became accustomed to the sound and seemed to pay no attention to it. It is unlikely that you will need to worry greatly about keeping most fishes out of a regularly-used swimming area, as most will probably avoid it them- selves. Sharks and barracudas occasionally enter such areas, but attacks by these fishes in swimming areas are not common in American waters. Attempts to repel these fishes by various mechanical devices have not proven successful. Research at the Institute of Marine Science, University of Miami, has shown that certain patterns of pulsed low frequency sounds will attract sharks and some other predators. |
|||
| go back to Questions |
|||
| Q&A 11. | I have heard that sound waves of a particular frewuency will drive away sharks. Could you send me some detailed information? What kind of apparatus would be required to project sounds into the water? Camp Hill, Pennsylvania |
||
| We are not aware of a single controlled experiment indicating that sounds of any frequency will repel sharks. A loud noise of any detectable frequency might startle a shark (or any other animal) but a shark hearing such a sound might well return soon to investigate the disturbance. Some skin divers maintain that they have chased sharks off by yelling at them underwater, but this does not always work. Investigators at the Institute of Marine Science, University of Miami, have studied for some years the hearing of sharks and the effect upon them of underwater sounds. All experiments to date indicated that pulsed low frequency sounds (such as made by a struggling animal) will attract sharks. Other sounds played into the water have had no discernible effect upon sharks. Apparatus necessary to project underwater sound includes: a sound source, an amplifier, an underwater speaker, and a source of power. An estimate of minimum cost would be around $400. |
|||
| go back to Questions |
|||
| Q&A 12. | I recently read about the Moses sole (Pardachirus marmoratus) and the shark-repelling fluid it secretes. If this fluid is so effective, why is it not being used to protect divers and swimmers? Cheverly, Maryland |
||
| The toxin secreted by the Moses sole has been demonstrated to repel sharks, but the effective use of this secretion in protecting divers and swimmers will require the solution of several problems. The toxin itself is very unstable and some method of preserving it must be found. Then, because chemicals scattered around a diver disperse too fast to provide effective protection, the toxin would have to be incorporated into an ointment that a diver might apply to himself. If so, danger exists that the toxin may get into the bloodstream through the diver sustaining a cut. The toxin is both a neurotoxin and a hemotoxin and will attack and destroy red blood cells. The ultimate solution to this problem may lie in the way the sole itself escapes such ill effects. This is still being investigated. |
|||
| go back to Questions |
|||
| Q&A 13. | Is it feasible to use dolphins to patrol beaches and chase away sharks? Shreveport, Louisiana |
||
| Experiments were conducted in the early 1970s at Mote Marine Laboratory, Sarasota, Florida to determine the feasibility of using dolphins as an antishark device. A male bottlenosed dolphin (Tursiops truncatus) was caught in the Gulf of Mexico and placed in a large tank at the laboratory. Initial tests with the animal, which was named Simo, suggested that bottlenosed dolphins and some species of sharks are not natural enemies. The Mote researchers were able, however, to train Simo to attack and drive off several species of sharks. The only shark that Simo refused to attack was a bull shark (Carcharhinus leucas). Considering, however, the relatively low numbers of dolphins compared to sharks, as well as federal restrictions on capturing and molesting dolphins, the idea of using these marine mammals to patrol beaches is probably not feasible. |
|||
| go back to Questions |
|||
| Q&A 14. | On a television program, it was stated that sharks fear the banded sea snake and that some divers have painted their wet suits to resemble this animal to ward off shark attacks. Is a striped wet suit actually an effective shark repellent? San Diego, California |
||
| Striped wet suits do tend to deter sharks from approaching divers, but not for the reason stated. Sharks are not in fear of the banded sea snake and, in fact, actually prey upon it. The reason for the deterrent effect appears to be that sharks are frightened by the presence of a 6- to 8-foot (with flippers) creature that is strongly and unusually colored. This would also explain why Atlantic sharks, which never come in contact with sea snakes, avoid divers in striped wet suits. The behavior of sharks is not well understood, and so the above method of repelling them is not completely foolproof. It should be kept in mind that the individuals involved in testing the striped wet suits are experienced in diving in shark-infested waters and know how to avoid truly risky situations. For the majority of divers, the best way to avoid shark attack is still simply not to dive in waters where these animals are seen. Illustrations of the various sharks likely to be seen by divers are presented in Sharks and Other Dangerous Sea Creatures by Idaz and Jerry Greenberg, 1981, 64 pages, $4.95, available from the Planet Ocean Book and Gift Shop (refer to Sea Frontiers book section for ordering instructions). |
|||
| go back to Questions |
|||
| Q&A 15. | Has an effective means of preventing shark attacks been developed? Darien, Illinois |
||
| No. Shark Chaser, the first repellent in widespread use, was introduced in World War II, primarily to allay fears of servicemen operating at sea. It consisted of nigrosine dye, which acted as a visual screen, and copper acetate, which in preliminary tests seemed repulsive to the smooth dogfish (Mustelus canis). Postwar tests, however, indicated that any deterrent properties of Shark Chaser were due to the dye alone, which under most conditions dispersed too rapidly. In other tests, transmission of loud startling sounds and those of a known shark predator, the killer whale, dissuaded captive sharks; however, in the field, some species habituated to the sounds rather rapidly. Equally unreliable are striped wet suits that mimic the coloration of venomous sea snakes. Sharks might avoid a large creature (diver) having this appearance, but such behavior is unpredictable since some tropical Pacific and Indian Ocean sharks may prey upon banded sea snakes. A prototype suit of mail worn over a wet suit has protected divers from attacks by sharks less than 8 feet long (see Sea Frontiers, vol. 28, no. 3 pages 148-152). Now known as Neptunic, the $5,200 two-suit system also has 23 laminated Kevlar plates attached to the wet suit to distribute bite pressure over a larger area. This is an unlikely outfit, however, for bathers, surfers, and nonworking divers. The shark billy, bang stick, and carbon-dioxide dart are useful only if the diver sees the shark's approach and has the expertise to use these dangerous weapons (a nonfatal hit may make a shark more likely to attack). Offshore nets have been used to protect swimmers on South African and Australian beaches (see Sea Frontiers, vol. 11, no. 3, pages 130-138). Electrical barriers have also been used successfully, but they are expensive to maintain and dangerous to divers. Bubble curtains, deployed in similar situations, failed to deter sharks. For survivors of disasters at sea, Shark Screen, a black plastic bag held upright by flotation rings, can provide some protection. Inside the water-filled opaque bag, an individual is hidden visually and chemically (no scent is released); see Sea Frontiers, vol. 15, no. 4, page 203. Recent research has involved natural chemical repellents. For example, pardaxin - a chemical in the defensive, noxious secretion of the Red Sea Moses sole (Pardachirus marmoratus) - has proved repulsive to sharks in both laboratory and field tests. Research at the University of Miami Rosentiel School of Marine and Atmospheric Science has shown that similar chemicals, known as surfactants and commonly used as industrial detergents, share this capability. Drs. Samuel H. Gruber and visiting scientist Eliahu Zlotkin found that one - sodium dodecyl sulfate-is ten times more effective than the freeze-dried toxic secretion of the Moses sole. Sodium dodecyl sulfate disperses rapidly in water, however. Therefore, it cannot be used as a shark repellent until development of a packaging method that will slow its dispersal without altering its effectiveness. |
|||
| go back to Questions |
|||
|
|
|||
|
Rosenstiel School of Marine & Atmospheric Science Library
University of Miami, FL USA 4600 Rickenbacker Causeway, Miami, Florida 33149 Phone: 305 421 4060 Fax: 305 421 9306 E-mail: libcirc@rsmas.miami.edu |
 |
go to the top |
|