228 



BULLETIN OF THE BUREAU OF FISHERIES. 



blasts; an insect lan,-a; a green gelatinous mass including Cladoceran shells and prob- 

 ably composed of partly digested algse. 



Forbes and Richardson (1908) say of the common shiner : " It is especially a minnow 

 of creeks and the smaller rivers — our coefficients for which are 3 and 2.45, respectively — 

 scarcely ever occurring in either lakes or the smaller streams. It shows also a marked 

 preference for clear waters." Hankinson found this species in Walnut Lake, chiefly on 

 shoals with "abundant luxuriant aquatic vegetation and black bottom soil." It was 

 common on but one shoal. Its abundance and wide distribution in Douglas Lake are 

 unusual. It occurs not only in the lake but is the commonest fish taken in the seine in 

 Maple River. According to the writer's unpublished observations, the species breeds 

 only in running water on gravel bottom. Maple River and Bessie Creek afford the con- 

 ditions of its known breeding grounds. Moreover, the young fish have not been recog- 

 nized with certainty in the lake, which adds to the probability that it does not breed 

 there. It is more likely that the adults travel from the lake to the breeding grounds in 

 Maple River and Bessie Creek and that when partly grown the young go from the breed- 

 ing grounds as far as the eastern end of the lake, a distance along shore of about 6 miles. 

 The breeding grounds of this most important bait fish of the lake should be located and 

 preserved. 



Ameiurus nebulosus (Le Sueur), common bullhead, does not appear to be abundant. 

 In 191 1 four were taken on the hook in the vegetation on the east shore of South Fishtail 

 Bay. Three of them measured 9K inches in length and the fourth loK inches. The 

 records for 1912 are given below: 



Table II. — Records of Ameiurus nebulosus Taken :n Douglas Lake in 1912. 



None were taken in gill nets set at greater depth than 12 feet, so that they are 

 probably confined to the vegetation of the slope and to similar situations elsewhere. The 

 largest specimen taken is 6 inches shorter than Hankinson's (1908) largest (Hankinson's 

 measurements include the caudal fin), and 7 inches shorter than the Illinois maximum as 

 recorded by Forbes and Richardson (1908). Examination of the contents of two stom- 

 achs shows nothing unusual except the inclusion of a bumblebee. 



Young individuals of this species were taken in July at various points along the 

 shore of North Fishtail Bay and in an adjacent beach pool. In 1909 swarms of young 

 were seen in the same place together with the male. In August they had reached a 

 length of an inch and a quarter. 



Umbra limi (ICirtland), mud minnow, has not been taken in the lake itself, but is 

 abundant in the oxbow ponds that have been cut off from Maple River near the lake. 

 It should occur in the mucky bays and estuaries of the lake itself. 



Esox LUCIUS (l,imi3^us), common pike, or pickerel, is the largest and one of the most 

 abundant fish in the lake. The following table gives data concerning 22 individuals of 

 this species. 



