5o8 Roosevelt Wild Life .Imials 



surface and frequently jumping out and skipping along over the water. This habit 

 has given them the name "Skipjack." 



Breeding Habits and Life History. Few notes were obtained on the breed- 

 ing of the Silversides in Oneida Lake. Those taken in September, 191 5. were 

 undoubtedly young of the season for they were all small, uniformly sized specimens 

 from 13^ to 2 inches long. The four Silversides taken at other seasons, April, 

 July, and October, were 2^ to 4' 4 inches in length. Four and a half inches is 

 near the maximum size of the species. Calm ( 'ij. ]). 73 ) studied the growth of this 

 species in Oconomowoc Lake, Wisconsin, from the average size of 11.2 mm to a 

 maxinuun size of 76.2 mm. 



The species breeds about Ithaca in May and June, in quiet lakes, streams 

 and ponds. Its eggs bear filaments (Eigenmann, '18, p. 1044) attaching them to 

 vegetation, according to Wright and Allen ('13, p. 5). Richardson ('13, p. 411) 

 found fry ^-^ inches long abundant and in schools in June, 191 1, near Havana, 

 Illinois, He says that they swim near the surface with a characteristic wiggling 

 movement, seeming to keep in the open spaces between the smartweed and the 

 Potamogeton. In spawning, the fish of a pair evident!)- wind in and out among 

 water plants. Evermann and Clark ( '20, p. 378) say that it probably spawns in 

 Lake Maxinkuckee in the latter part of June and through July. Hubbs ('21, 

 p. 270) made an intensive study of this species in 1920, in Portage Lake and 

 adjacent waters in southern Michigan, including the Huron River. He found the 

 breeding activities at their height (hn-ing the last of May and early June, after 

 the surface waters had been heated above 68° F. Spawning occurred in the shoals 

 of the lake and in the Huron River. "The most densely populated breeding area 

 was the moderate current of the river, over a washed gravel bottom," at depths 

 of about one to four feet. He gives the following account of the spawning 

 activities: "Particularly after the height of the breeding season, the males in these 

 spawning areas were shown by frequently repeated observation greatly to outnum- 

 ber the females. Single males were at all times numerous here, but the only females 

 observed were paired with from one to several males. Each male appeared to 

 command a rather illdefined area of surface water, in moderate current two to 

 four meters long by one or two meters wide. I<'roni this area each guardian male 

 vigorously drove off invading males, returning later, though not invariably, to 

 approximately the .same spot. During the height of the breeding activities, how- 

 ever, no such areal restriction of individuals was apparent, for most or all of the 

 males as well as the females were engaged in their wild .spawning. 



"Apparently upon entering the spawning area, the females were quickly recog- 

 nized as such by the males, who gave chase. The fi-malc in all cases first made 

 away at high speed very clcsely pursued by one to sc\cral males. LTsually she 

 leaped through the air, often repeatedly, in what appeared to be her vigorous eflforts 

 to elude the pursuing male. Only once was the actual spawning act observed, but 

 at such close range and under such conditions of illumination that the details of 

 movement could be closely followed." The eggs ;u-c oNlmdcd cnnsicler.-ibly above 

 the bottom and sink very slowly: llu'v art- \m-11 su|iplie(l with nil glubules ;md with ;i 

 flotation organ in the form of a long filament. Tliibbs thinks that an egg must be 



