648 RETROSPECT 



The United States Navy has supported basic research on elasmobranchs for 

 many years, largely through the Office of Naval Research. The main motive 

 for this support is an obvious one: sharks have been a recognized hazard to 

 human beings in the sea for centuries. A secondary, though in the long term 

 perhaps more important, motive was that knowledge of the shark's biology 

 and sensory capabilities might provide insight into many biological processes. 

 Perhaps this realization became clear only when details about the remarkable 

 sensory sensitivity of sharks began to emerge. 



Because the main impetus for studying sharks is their danger to man, the 

 history of naval shark research is tied closely to that of the Navy's standard 

 shark repellent, "Shark Chaser." Before the Second World War, if the Navy 

 had any official position on sharks, it was that they were largely harmless to 

 uninjured, alert people in the water. This attitude is understandable since 

 there was disagreement among scientists and naturalists as to how dangerous 

 sharks really were to man. On the whole, most sharks were considered 

 scavengers that might try to bite almost anything in the water and might be 

 attracted to wounded or dead men but could be expected to leave healthy 

 ones alone. 



After the war started, shark incidents were reported from the front, 

 especially in the Western Pacific. It was not clear, however, how serious the 

 problem was, or even whether there was a problem. Reports from the front 

 lines were censored, and the popular press often portrayed sharks as 

 harmless. An article in Collier's magazine in 1944 was entitled "The Shark is 

 a Sissy." Even now, it is still not clear how dangerous sharks actually were to 

 men in the water. However, they were certainly a psychological threat, and 

 the fear of sharks became a noticeable morale problem. 



To deal with the problem, meetings were held in Washington in 1943. It 

 seemed that the best way to handle this fear of sharks was to develop a shark 

 deterrent, and it was suggested that the best possibility was a chemical 

 repellent. It has since been pointed out that perhaps chemical shark 

 repellents are not the most effective kind. For example, since a chemical 

 repellent has never been used against such terrestrial predators as tigers or 

 grizzly bears, why should one be useful against marine predators? 



In the first place, there is no real evidence that the proper chemical 

 repellent might not be effective to protect man against terrestrial predators. 

 The most serious problem would probably be that man is sharply attuned to 

 the same chemoreceptive system as these predators. For example, a vial of 

 mercaptins such as a shunk produces would very likely repel predators, but 

 to a human the smell would be unbearable. On the other hand, man is not 

 attuned to water-borne chemical repellents or attractants the way aquatic 

 animals are. Furthermore, evidence accumulating in recent years indicates 

 that chemoreception may be much more important in the freshwater and 

 oceanic realms, than in the terrestrial environment. All of this suggests that 

 looking for a chemical shark repellent was not unreasonable and that 

 ultimately, chemoreception may still provide the best means of repelling 

 sharks. 



When the assembled Navy, Coast Guard, Army Air Corps, and Merchant 



