This combination of stimuli, although producing the desired end 

 resultj might not be practical to use in rivers of large size and high 

 turbidity. A t-est of this type might be simulated by using a submerged 

 fire hose to force the fish into one or the other extremes of a pond. 



For all other trials the wampus was placed where the visual and 

 mechanical stimuli were minimized or absent. The powerful jets from 

 the turbine were directed so that they did not impinge upon the structure 

 or the fisho Upon one occasion^ the transducer was inadvertently shifted 

 so that a stream of turbulent water was directed into section no. 1, The 

 trout immediately oriented themselves in an upstream fashion. At least 

 one fish dashed into the jet and flipped at the surface as though feeding 

 upon particles carried by the current. The majority remained at a dis- 

 tance of approximately 12 feet in a normal schooling pattern. 



Small txirtles, frogs 5 toads, snails and assorted aquatic insects 

 were kept in live boxes d'oring the trials. The pond was heavily popu- 

 lated with frogs and snails at all times. None of the organisms 

 appeared to notice the sound, Eren when the live box containing them 

 was placed within 8 inches of the wampus (above the jets) they made 

 no struggle or attempt to avoid the sound. Some of the small brown 

 trout be:;ame quiescent when their cage was placed in close proximity 

 to the noise, and remained on the bottom resting partially on their 

 sides or on their fins as though exhausted, rthen they were removed, 

 they resumed their normal swimming movements and appeared unaffected. 

 All test animals, especially the fish, were carefully watched for in- 

 juries and abnormalities, but none appeared. 



Calibrations, or measurements of the sound field intensity were 

 made using standard hydrophones (Barcroft, Q-h, No. 29), The receiver 

 was suspended near the mid-point of each section or compartment to give 

 the readings shown in Tables 1 to 3. 



Without air, the wampus seemed to produce a noise of greater in- 

 tensity as judged from the hydrophone readings. When the air to the 

 sound head was cut off, the sound escaping from the water changed from 

 a throaty roar to a metallic hammering. This difference, and the measure- 

 ment of it, is the result of a change from a loudness level to an in- 

 tensity level - the difference between the boom of a cannon and the crack 

 of a rifle. The wampus trials were then discontinued. 



Again„ contingency tests betiveen sound trials and controls shovied 

 highly significant differ -nces of distributions of fishes within the 

 trough. No indication, however, that sound caused the differences was 

 evident. 



32 



