REPORT OF COMMISSIONERS OF INLAND FISHERIES. 17 



of a large city. They were especially abundant, and therefore es- 

 pecially noticeable, last year at the head of our Bay. They move 

 more rapidly than is generally supposed, and it would not be unusual 

 for them to go from Providence to Newport in a very few days. 

 Outside the Bay, in the schools of menhaden caught "off shore/' 

 the disease has never been observed. 



As a tentative explanation of the phenomenon, we would suggest 

 the following: 



The fish contract the disease in the polluted water near our 

 cities. Their liability to the disease is greater than that of any other 

 fish, because of their habit of feeding. In many instances, while the 

 disease is incubating, they swim unnoticed many miles away toward 

 deeper water; then, when the disease is developed, they suddenly 

 appear at the surface. The phenomenon is liable to occur in any 

 year, but will become obnoxious only when the fish are unusually 

 abundant near the cities. The very prevalent opinion that the fish 

 die because of a worm in the head is probably not valid. Worm-like 

 parasitic copepocls (degenerated Crustacea) occur in menhaden very 

 commonly, in those which are healthy and are taken in the schools off 

 shore as well as in the sick ones in the estuaries. 



