EFFECTS OF EXPLOSIVE SOUNDS. SUCH AS THOSE PRODUCED BY 

 MOTOR BOATS AND GUNS, UPON HSHES. 



By G. H. Pabkeb, S. D., 

 Professor of Zoology, Harvard University. 



SENSE OF HEARING IN FISHES. 



That sounds affect many fishes has long been recognized by fisher- 

 men and naturalists. No less an authority than Izaak Walton de- 

 clared that it should be a rule with him to make as little noise as 

 possible when he was fishing, lest he be heard and catch no fish. 

 Nevertheless it has been only within the last few years that the sense 

 organs concerned with the reception of sound in fishes have been 

 definitely identified. 



Using the term sound to include any vibrations of the water, from 

 such slight movements as result from waves and currents to the 

 vibrations that emanate from the impact of solid bodies under water 

 or from the more violent discharge of explosives, it may be said that 

 sounds affect fishes through three sets of sense organs — the skin, the 

 lateral-line organs, and the ears. Within recent years it has been 

 demonstrated that a fish can feel sounds through its skin in much the 

 same way that a human being can feel the vibrations of a musical 

 instrument when his hand is in contact with it. It has also been 

 demonstrated that certain fishes sense relatively low vibrations, such 

 as trembling movements of the water, by means of the lateral-line 

 organs. And furthermore, though this point has been disputed, it 

 seems clear to the writer through work carried out under the auspices 

 of the Bureau of Fisheries that the internal ears of fishes are not only 

 organs for the adjustment of bodily motions and equilibrium, but 

 also organs of hearing. 



THE QUESTION OF MOTOR-BOAT NOISES. 



If, then, fishes are sensitive through so many channels to sounds, 

 the question naturally arises as to the effect of the introduction of 

 motor boats and other sound-producing mechanisms on the fishes of 



3 



