43] STUDY OF SOUTHERN WISCONSIN FISHES— CAHN 43 



themselves in the ooze. Their tenacity of life is unique among our fishes, 

 in spite of which they are never used locally as bait, presumably because 

 of their dark color. The food is very largely aquatic plant material, duck- 

 weed (Lemna), particles of Elodea, Ceratophyllum,etc, together with any 

 minute animal life that may be attached to this growth. Thus I have 

 found particles of Hydra sp. in the intestine, probably off of Elodea. They 

 spawn very early, probably as soon as the ice goes off the ponds, as I have 

 no gravid females later than April 12. In the Fox river I have never seen 

 a mud-minnow more than 3 inches long, while in the ponds near Okauchee 

 lake I have taken them 5| inches in length. Generally known as "young 

 dogfish" locally. 



Family esocidae 



54. Esox americanus (Gmelin). Grass Pickerel; Little Pickerel. 

 Found in only one locality in the county, the headwaters of the Fox 



river in the vicinity of Lannan. It was quite a surprise to find this little 

 pickerel so far north as this is one of the most northern records, but in 

 the northern waters of the Fox river and until the river becomes about 

 twenty feet wide, this pickerel is the dominant and characteristic species. 

 In this region the water is muddied by carp activity, normally but two 

 feet deep, slow and sluggish, but not stagnant, and the bottom is a mixture 

 of sand and mud. Here the pickerel lives on mud minnows and crayfish, 

 and attains a length of 9 inches, though I have taken few so large. The 

 fish spawn in typical pickerel manner, coming up into the overflowed 

 marsh during the spring flood, to lay their eggs in the shallow water. The 

 young pickerel are about two and a half inches long at the end of the first 

 summer, their food consisting of young crayfish (Cambarus propinquus) 

 which are unusually abundant there, and darters and small minnows 

 (Notropis hudsonius, N. cornutus, Umbra limi) with an occasional Physa 

 and Gammarus. The fish are so small as to be of no economic value. 



55. Esox lucius (Linn). Great Northern Pike; Pickerel. 



The common pickerel of the region. Very abundant in all of the lakes 

 and less so in all of the rivers, except during the spawning season. The 

 greater part of the summer is spent just off of the sand bars in water 18 

 to 25 feet in depth, where the voracious fish lie in the Potamogeton beds 

 and gorge themselves on any passing fish of convenient size. Feeding is 

 almost entirely during the daytime and only very seldom is one caught at 

 night. The food is normally fish, all species of minnows and small Cen- 

 trarchidae included, with crayfish varying the diet during late summer. 

 They grow to very great size, the largest I have weighed was 27|- pounds; 

 it was caught in the Oconomow river near Fowler lake. I have many 

 records of fish weighing between 15 and 18 pounds, but each year sees 

 fewer of these large specimens caught. Newspapers published during the 



