128 Man Against Shark 



How good is Shark Chaser? Like any question associated with sharks, 

 this one has a variety of answers. 



Developed in a wartime crash program during which there was Uttle 

 time for extensive testing (as it was, the repellent was not issued until 

 late in the war). Shark Chaser was not tried on enough sharks under 

 enough conditions to satisfy careful scientists. 



When several sharks are in a feeding frenzy, for instance, nothing 

 seems strong enough to repulse them. 



Burden, one of the developers of the repellent, said: "Let us assume 

 that a lot of blood has gotten in the water prior to the introduction of 

 the repellent material. Let us assume further that voracious sharks are 

 present in large numbers. Under such circumstances sharks have fre- 

 quently been seen biting at oars and boats, with such savage determina- 

 tion that they completely ignored heavy blows. This would seem to in- 

 dicate that at some point in the characteristic shark-feeding program, 

 the olfactory sense no longer plays a dominant role and is superseded by 

 a mob-impulse in which visual and auditory senses both have probably 

 played a part. This mob-impulse might be likened to the stampede be- 

 havior in animals. Under these conditions it is very doubtful if any chem- 

 ical repellent would inhibit their feeding behavior thoroughly." 



Burden believed, however, that "the sense of smell initiates the sub- 

 sequent feeding pattern, so that if this behavior can be arrested at the 

 outset through a repellent, the more violent aspects of it could not come 

 into being." 



This may have been the case in a test of the repellent conducted by 

 the Fish and Wildlife Service in 1945. In a fishing ground off Massachu- 

 setts, shark repellent was spread around the nets of a Gloucester mackerel 

 seiner, the Angle and Florence. The Fish and Wildlife Service reported: 

 "In spite of the abundance of sharks, the Angle and Florence received 

 no damage to its nets, and caught about 58,000 pounds of mackerel. 

 Other boats fishing in the same area, but without protection against 

 sharks, averaged only 5,000 to 25,000 pounds of fish, and suffered severe 

 damage to their nets." 



That was in 1945. Only in recent years have marine biologists begun 

 to probe very deeply into why and how a shark responds to food, in- 

 cluding human prey. It has been learned, for instance, that the shark 

 may vary its feeding pattern from a slow, determined assault on the food 

 to an attack consisting of rapid, seemingly wanton bites. But little is 

 known about what triggers these different modes of feeding— or attack- 

 ing. 



The Shark Chaser repellent consists of about 20 per cent copper 

 acetate, believed to be repugnant to sharks, and about 80 per cent nigro- 

 sine dye, which diffuses in the water as a blue-black cloud similar to 

 the inky fluid ejected by squids when they become alarmed. 



