Anti-Shark Warfare 123 



"It would appear from these data," Gilbert reported, "that the bubble 

 curtain is ineffective as a barrier to Tiger sharks ... It is highly prob- 

 able . . . that some of the sharks which seemingly were repelled . . . 

 normally would have turned in this area of the pen anyway." 



Other methods for repelling sharks have been tried but with equal 

 lack of success. Let us take a look at some, starting with the most im- 

 pressive. 



A great crowd gathered along the waterfront of Margate, South 

 Africa, one day in 1958, for a spectacular show was going on about 

 1,000 yards from shore. The frigate Vrystaat of the South African Navy 

 was depth-bombing sharks. Geysers of water shot into the sky as the 

 Vrystaat set off 25 depth charges. Seven sharks were counted dead. And, 

 though a score of about 3^/4 depth charges per shark does not sound 

 impi-essive, a newspaper reported, "There is every reason to believe 

 that the operation will be a great success." 



Actually, there is every reason to believe that the unusual naval 

 warfare against the shark attracted far more sharks than were killed. 

 An underwater explosion will kill bony fish over a wide area. Their 

 swim bladders burst from the concussion. Sharks have no swim bladders, 

 and they are impervious to any explosion except a virtually direct hit. 



The bony fish stunned or killed by an explosion immediately lure 

 sharks to the area. An eyewitness to such a phenomenon reports that 

 sharks converged to feast on the wounded and dead fish within 20 sec- 

 onds after an explosion. The British Shallow Water Diving Unit at 

 Nassau in the Bahamas reported: "We threw TNT blocks into the water, 

 and within five minutes of the explosion the area was full of sharks feeding 

 on the dead fish. They averaged about 6 feet, the biggest being 8 feet. 

 It was a remarkable sight." 



Survivors of the torpedoing of the U.S. Destroyer-Escort Frederick 

 C. Davis on April 25th, 1945, during World War II, told of sharks appear- 

 ing and attacking survivors after two depth charges on the sunken ship 

 had gone off underwater. The muffled explosions, not strong enough to 

 cause much injury among the men in the water, indirectly killed many 

 of them because the explosions brought more sharks to the scene— and 

 the scene was the center of the Atlantic Ocean. 



The chemical shark repellent was bom as a wartime weapon to be 

 used not only against sharks, but also against fear of reputedly shark- 

 infested waters. Anxious mothers wrote their Congressmen about the 

 sharks, and even the President received similar worried letters. Service- 

 men who should have been worrying about survival in combat were 

 being unnerved by dread of an enemy more horrifying than a man with 

 a gun. 



Fear of death by bullet or bomb did not seriously weaken morale, 



