in a similar pattern in nearly identical num- 

 bers. This frequency (50 kc.) was tried again 

 and again informally, without results which 

 could be assessed as conclusive. 



Any frequency which elicited even a sugges- 

 tion of a response, was repeated informally. 

 The equipment was given a series of tests 

 utilizing experimental signals ranging from 

 intermittent pips to siren effects of several 

 frequencies. The complete unconcern of the 

 fish to any of these signals was convincing 

 that they were unaffected. It was decided, as 

 a final test of this conclusion, to beam the 

 transductr across section No. 2 so it would 

 act as a sound "fence" to keep the fish in 

 section No. 1. Tests No. 51 through 58 (figs. 

 17 and 18) showed no response. Tests No. 59 

 through 61 (fig. 18) were thought to be indica- 

 tive, so these tests were repeated but without 

 success. The remainder of the high frequency 

 tests, both formal (figs. 18 and 19) and in- 

 formal were unproductive. There was no 

 indication that this signal generator or any 

 frequency produced by it would be of any use 

 as a stimulus for leading or guiding small 

 fish. 



An incidental finding of the above tests was 

 an indication of conditioning in the experi- 

 mental fish. As the trials progressed, there 

 was a distinct tendency for the fish to learn 

 to remain in pen No. 1 (fig. 20). 



"WAMPUS" - UNDERWATER TURBINE 



In spring 1949 experimentation with sound 

 was continued at the Leetown station with the 

 help of the U.S. Naval Ordnance Laboratory. 

 The first piece of equipment tested was an 

 underwater turbine (fig. 21) used during World 

 War II as a towed sound target for torpedoes 

 and mines. This noisemaker required for its 

 operation a 500-gallon per minute water pump 

 and a 150-pound capacity air compressor 

 (fig. 22). An overhead trolley line was rigged 

 to enable the sound head to operate at varying 

 distances from the fish in the counting struc- 

 ture. Because of its use in naval warfare, 

 the sound head, dubbed the "wampus" early 

 in its development, is still in a classified 

 category. It is not possible, therefore, to 

 describe this underwater turbine in detail. 

 Of greater importance, however, is the nature 

 of the frequency band emitted and its intensity, 

 which we have obtained permission to discuss 

 in general terms. The maximum signal re- 

 corded was about 3 volts, which at 56 micro- 

 volts per microbar, would correspond to a 

 pressure of about 55,000 dynes/cm.^ This is 

 real underwater thunder. By way of connpari- 

 son, 1 dyne/cm.^ in underwater sound is a 

 moderate noise of the sort made by a small 

 boat sloshing along nearby. A loud underwater 

 sound level would be made by a large ship 



passing at close range, which might register 

 30 to 40 db above 1 dyne/cm.^ The standard 

 for quiet used by the telephone company is 

 .0002 dynes/cm. 2 



Some frequency response curves were ob- 

 tained on the wampus with and without air 

 and at 100 p.s.i. water pressure. With air 

 there was a fundamental frequency of about 

 50 to 75 c.p.s. and all harmonics up to 3,000 

 or 4,000 c.p.s. Without air, the fundamental 

 was about 75 to 100 c.p.s. and with all har- 

 monics up to 2,000 c.p.s. The shifting of the 

 fundamental frequency made it difficult to keep 

 the wave analyzer lined up on any harmonic 

 long enough to get accurate readings. These 

 levels were greatly dependent on the standing 

 wave pattern in the pond. 



The optimism of those who hoped to find 

 something that would "work" in guiding fish 

 was never greater than on the day of the first 

 trial of the equipment. The U.S. Navy fire 

 department provided a fire truck to pump a 

 sufficient stream of water to operate the 

 wampus in a concrete torpedo testing tank. 

 The noise produced is the result of the 

 emission of interrupted jets or "slugs" of 

 water and air being expelled from the sound 

 head into the surrounding water as shown in 

 figure 21. The general effect at close range 

 is rather awesome. The noise escaping from 

 the surface might be compared to that pro- 

 duced by a medium size air-cooled airplane 

 engine and propeller running full speed at an 

 equal distance away. The sound waves set up 

 in the water of the torpedo tank were suffi- 

 ciently strong to vibrate the surrounding 

 concrete under foot. The observers felt pecul- 

 iar prickling sensations of the skin and hair 

 follicles when hands were placed in the water 

 approximately 6 feet from the sound source. 

 A slight nausea was experienced by a few. 



For the first exploratory tests at Leetown, 

 1,000 rainbow trout 10 to 12 inches in total 

 length were placed in the counting structure, 

 100 fish to a section, as in previous tests. 

 The wampus was run out on the trolley to a 

 position 100 feet from the fish m the counting 

 structure, and 1.5 feet below the surface of 

 the pond. The exploratory test of 10 minutes 

 duration brought no observable reaction from 

 the trout. Their distribution within the struc- 

 ture remained approximately the same. The 

 level of sound intensity at 100 feet was meas- 

 ured and determined to be 4 microvolts or 

 12 db _above 1 dyne/cm. ^ Several hundred 

 2-inch brown trout fingerlings in a live box 

 were unaffected or indifferent. 



Having determined that the trout showed no 

 reaction to the wampus at a distance of 100 

 feet, the head was moved to a point 30 feet 

 from the fish in the first section. When the 



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