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ECOLOGY AND BEHAVIOR 



of the phenomenon is provided in this volume by Myrberg (1978). Pulse 

 intermittency is especially important in eliciting oriented behavior of sharks, 

 and an irregular series of pulse trains is more effective than a continuous 

 output. 



The use of sound to attract sharks is common among Pacific shark fisher- 

 men. It has been documented in the Society Islands (Gibbings 1948, Price 

 1944) Gilbert Islands (Anell 1955, Gatty 1978), Fiju (Gatty 1978), Caroline 

 Islands (Price 1944) and several other island groups (Anell 1955). 



The most commonly used sound sources are rattles made of coconut shells 

 (Figure 1). Broken coconut shells may be strung on a twig bent into a circle, 

 so that the rattle resembles a necklace. In the linear model of this same 

 apparatus, the shells are strung on a rope made of plant fiber, and small 

 cowrie shells may be attached along the rope to provide a more rapid, 

 higher-pitched, jingling sound that contrasts with the low-frequency sound 

 from the coconut shells. 



The methods of using coconut rattles fall into at least two categories: 



1. The rattles are vigorously worked up and down, churning the water 

 surface into a foam. The sound is often claimed to resemble a shoal of small 

 fish breaking on the surface (e.g., Gibbings 1948). In a demonstration of this 





Figure 1 Shark rattle lures, constructed from coconut shells, 

 Micronesia. 



