624 Lake Maxinkuckee, Physical and Biological Survey 



the menu of the water-dog, while the smaller, softer-shelled mol- 

 lusks, insect and other larvae, and perhaps other small aquatic ani- 

 mals, are utilized to some extent. 



According to Mr. J. J. Stranahan, for many years Superintend- 

 ent of the Fish Cultural Station at Put-in-Bay, the water-dog is 

 very destructive to the eggs of the whitefish. He states that in Jan- 

 uary, 1897, many of these animals were pumped up with the water 

 supply of the Put-in-Bay station and that the stomachs of a con- 

 siderable number of them contained whitefish and cisco eggs, the 

 contents of one stomach consisting of 288 whitefish eggs and four 

 cisco eggs. From June to August, 1894, while Dr. H. F. Moore 

 of the Bureau of Fisheries was engaged on investigations in Lake 

 Erie he examined the stomach contents of a number of water- 

 dogs at Sandusky and elsewhere and found fish eggs present in 

 many cases. 



While writing this account (August, 1907), a specimen of 

 water-dog was received by the Bureau from a lake near Irwin, 

 Colorado. Its stomach contained six or eight examples of Gam- 

 marus (a small crustacean) and several small bits of rotten wood, 

 the latter taken incidentally along with other food. 



Carman* states that the water-dog subsists on crustaceans, in- 

 sects and mollusks. 



It is undoubtedly a bottom feeder, and its habit of walking or 

 crawling about over the bottom makes the finding of fish nests and 

 the destruction of the eggs a particularly easy matter. The evi- 

 dence, therefor, would seem to be conclusive that the water-dog 

 is wholly carnivorous in its habits ; that its food consists chiefly of 

 small fish, and in season, of fish eggs, along with a smaller propor- 

 tion of crustaceans, mollusks, insect larvaB, etc. 



Water-dogs may be caught quite readily in any season on hooks 

 baited with minnows, crawfish, liver, bits of meat, or almost any 

 animal matter. Setlines placed by us for experimental purposes 

 at various depths and places in the lake usually yielded at least 

 one water-dog every time examined. When the hooks were set at 

 a greater depth than 35 or 40 "feet, however, they rarely caught 

 any. On hooks set in Lost Lake for catfish and dogfish, water-dogs 

 were often taken. 



Anglers often catch them while still-fishing in the spring, sum- 

 mer and fall, but it is during ice-fishing in the winter that they are 

 most troublesome and most frequently taken. All fishing through 



*A Synopsis of Reptiles and Amphibians of Illinois. Bull. Ill, State Lab. Nat. Hist., Vol. Ill, Art. 

 XIII, p. 383, 1891. 



