I04 



BULIvETIN OF THE BUREAU OF FISHERIES. 



way; they were then subjected to sound till they assumed a characteristic distribution 

 for this condition; and finally they were allowed to come to rest again. The time 

 occupied in these operations is recorded in the following table: 



Table VI. — Numbers op Individual Stenotomus, out of 5, Occurring in the Half of the Tank 

 NEXT THE Sounding Apparatus before the Fishes were Subjected to Sound, during Sound- 

 ing, AND After the Sound Had Ceased. 



An inspection of this table shows that during the period preceding the application 

 of the sound (7.35 a. m. to 7.45 a. m.) the distribution of the fishes was fairly uniform, 

 that during the application of the sound (7.50 a. m. to 8 a. m.) the fishes gradually with- 

 drew from the sound center, and that within 15 to 20 minutes after the sound ceased a 

 condition of distribution was attained fairly comparable with that seen at the beginning 

 of the test (7.35 a. m. to 7.45 a. m.). The conclusion to be drawn from these observa- 

 tions is that, though the direction of the locomotion of a fish can be very considerably 

 influenced by sound, this influence ceases very shortly after the sound ceases. 



In attempting to apply these conclusions to the problems presented in the handling 

 of fishes, several considerations must be kept clearly in mind. It is quite obvious that 

 in one way or another many fishes are stimulated by sound. But most of the sounds 

 that we deal with are generated in the air, and these sounds either fail to enter water 

 or enter it to so slight a degree that they are of little or no significance for the fishes. 

 The surface between water and air is an extremely difficult one for sound to penetrate 

 in either direction, so that most sounds that are generated in the water or in the air 

 stay in the medium of their origin. Hence many of the sounds that are produced by 

 the discharge of guns, etc., in the air enter the water to so slight a degree (as can be 

 ascertained by immersing oneself in the water at the time the sound is produced) as to 

 be unstimulating to the fishes, though they may be deafening to the observer in the air. 

 Such sounds as reach the fishes, however, not only stimulate them to move, but, as these 

 observations show, influence the direction of their movements. But this directive 

 influence is almost as short in duration as the stimulus. It is, therefore, improbable 

 that sounds of brief duration can have much effect on the temporary distribution of 

 fishes within their reach. That fishes should be attracted over any considerable area 

 or repelled from that area by sound would seem to demand some more or less contimwus 

 source of sound production. 



