EFFECTS OF EXPLOSIVE SOUNDS UPON FISHES. 5 



An observer was stationed on the float to note any response made 

 by the fish. Tests were made with the escape pipe out of water 

 and Avith it under water, but in neither instance was there any ap- 

 parent effect upon the fishes. Most of these fishes, and especially 

 the killifish, go down into deeper water when only slightly dis- 

 turbed, but in these trials they remained playing about on the sur- 

 face of the water while the boat passed and were in no observable 

 way disturbed until the swash from the boat struck the cage, where- 

 upon they generally dove to the deeper part of the receptacle. 



Another test of a like kind was carried out on mackerel {Scomber 

 scombrus). About 30 of these fish that had been for one or two days 

 in a large pocket at the end of a pound net about a quarter of a mile 

 from shore were gathered together by having the pocket pursed up 

 into a space about 25 feet square and 10 feet deep. In this space they 

 swam slowly about in a circle near the top of the water. 



When an observer stationed in a boat at the edge of the pocket rose 

 in the boat the fish very usually went to the bottom of their inclosure, 

 to return to the surface after the observer had taken his seat again. 

 While the observer was sitting and watching the fish a second per- 

 son ran a motor boat over a circular course about half a mile in 

 circumference, the course passing close to the pocket at one point. 

 As the motor boat passed the pocket the fish were closely scrutinized 

 by the observer. In no instance, either with the escape pipe of the 

 motor boat above water or under water, did the mackerel sink into 

 the deeper part of the pocket nor did they show in any other observ- 

 able way that they were disturbed by the noise from the boat. Seven 

 of them were then isolated in the cage previously mentioned and 

 tested under close inspection by running the motor boat past the 

 cage, but again the mackerel gave no evidence of being disturbed by 

 the noise. 



Although these tests seem to be quite conclusive in showing that 

 the faint noises produced in the water by a motor boat have no 

 marked effect on the ordinary activities of certain fishes, it is not 

 impossible that the same noises may interfere with other activities 

 of these fishes, such as feeding, pairing, egg laying, etc. The only 

 tests in this direction that were carried out had to do with feeding. 

 Hungry killifish, scup, and kingfish were placed in the cage pre- 

 viously used and the cage was fastened to a float so that a motor 

 boat could pass close to it. When the fish were* feeding vigorously 

 the motor boat was run by the cage several times, but in no case did 

 the fish give up feeding in consequence of the noise. 



Another test was made with baited lines. Two baited fish lines 

 were lowered from the edge of a wharf until the bait was about 6 

 feet under water. In a short time the two baits were surrounded by 



