REPORT OF COMMISSIONER OF FISH AND FISHERIES 49 



with proper facilities Dr. Dean is confident that he could have produced 

 enough fry to have made his work exceedingly profitable from a prac- 

 tical standpoint. He considers the vicinity of Delaware City especially 

 well adapted to the propagation of the sturgeon, and thinks there 

 would be no trouble in securing a sufiicient number of spawning fish at 

 the oroper season. He was there from May 14 to 23. Observations 

 were also made respecting the breeding and other habits of the stur- 

 geon, and Dr. Dean has now in course of preparation a comprehensive 

 account of the results of his investigations.' 



MORTALITY AMONG ALEWIVES, LAKE ONTARIO. 



Keference has frequently been made in the Fish Commission publi- 

 cations to the extraordinary mortality which occurs among the alewives 

 in Lake Ortario during every spring and summer, and which also, to 

 some extent, aftects other common fishes in the same waters. The cause 

 of this annual epidemic has never been determined j it has a widespread 

 distribution, and the number of dead and dying fishes which are often 

 cast upon the shores in some places is so great as to occasion much 

 inconvenience to residents and summer visitors from the unpleasant 

 odors arising from the decaying bodies. Mr. C. H. Strowger, of Nine- 

 Mile Point, near Webster, N. Y., has paid a great deal of attention to 

 this phenomenon, and the Fish Commission is indebted to him for much 

 information respecting it, as well as for specimens of the diseased fish. 

 In order to reach a more.comj)lete understanding of the subject, Dr. R. 

 E. Gurley was dispatched to Lake Ontario in the early part of June, 

 1893, and remained there about a month, visiting Nine-Mile Point, 

 Wilson, Charlotte, and Cape Vincent. He spent the most of this time 

 at the place first mentioned, where laboratory accommodations were 

 supplied by Mr. Strowger, who also assisted Dr. Gurley personally in 

 his investigations. 



From the statements of persons living along the shores of Lake 

 Ontario, the epidemic appears to begin in Ajjril, occasionally as early 

 as the latter part of March, reaches its maximum in May, and decreases 

 through June, although in some cases it may be found as late as August. 

 The May and June maximum of the epidemic coincides with the period 

 when the alewives are most abundant inshore. The diseased fish have 

 a patch of saprolegnia, usually from three-fourths of an inch to an inch 

 in diameter, on some i^arts of the body, but no other parasites were 

 found on any of the dead alewives examined. None of the vital organs 

 were affected by the fungus, the gills in particular always appearing 

 clear, and otherwise also the fish seemed to be in good condition. An 

 inflamed area was almost always noticed on the general surface of the 

 body under the patch of saprolegnia, and very generally a sore or ulcer, 

 the scales in such places being loosened or detached. In some cases 

 the fungus appeared to have eflected a lodgment in places where the 

 F. R. 93 4 



