254 REPORT OF THE COMMISSIONERS OF 



a large series of swarms, during a period of about two weeks, there is ground for believing that 

 the time of the guardian's care of the movements of the young extends from, at least, the stage 

 in which the yolk supply is exhausted, to that in which the caudal fin and scales have attained 

 the adult outlines — a time certainly not less than four weeks.* 



" The rate of growth of larvae of the same swarm has been observed to be approximatelv 

 uniform, the individual differences depending rather upon size than upon actual developmental 

 advances; larvae of apparently the same stage of development vary in length as much as three 

 eighths of an inch. In some cases, however, the range in development seems, as nearly as could 

 be determined, to have been equivalent to a difference of two or three days. 



" Upon the dispersal of the swarm, the larvae appear to make their way to the well-weede4 

 shallows of the neighborhood; here they remain during the first summer, occasionally taken 

 along adjacent shore reaches in the drawing of the minnow nets. Mr. Henry G. Meyer, to 

 whom the writer has hitherto referred for his kindness during collecting trips, has stated that 

 during the first summer many of the fishes will be taken in and near the mouths of the small 

 streams that feed the lake chain of Pewaukee. It may, at all events, be surmised that the 

 habits of the late larvae of Amia do not differ widely from those of the prevailing forms of the 

 local teleosts." 



III. Aeans 3aggested for l^edacing tt»e Nambers 



of tl)e DogfisI). 



The foregoing notes upon the spawning and habits of the dogfish provide the fish 

 culturist, I am convinced, with data which should enable him, and with relatively little 

 trouble, to materially reduce their numbers in localities where they abound. He 

 learns, for example, that these fish will repair to a more or less definite locality at the 

 time of spawning, and that here in the shallows their nests can be readily found and 

 destroyed. He concludes, furthermore, that without extraordinary effort he can secure 

 the male fish which guards the nest and young. This he can take either by snare or 

 by spear. As the first step in reducing the numbers of dogfish, he finds it of course 

 necessary to determine accurately the time of spawning; in this he is helped, since the 

 general limits of the season have been already indicated. The exact time of spawning 

 may usually be determined with but little difficulty, for the splashing of the fish during 

 the early days of spring may be looked upon as an indication that spawning has either 

 begun or is about to begin. An occasional rise in the shallows is thus found to mark 

 the preparation for spawning ; a continuous and noisy splashing, one which can be 



*"The writer has recently learned from his friend Mr. F. B. Sumner, that the period of the 

 attendance of the male is much longer than at first supposed. In Minnesota, Mr. Sumner records 

 the taking of a swarm of Amia larvae in which the individuals measured three to four inches in 

 length, and must have been about four months old. A remarkable fact in connection with them was 

 that all of these young fishes (females, therefore, as well as males, although no dissections were made 

 to determine sex) had acquired the characteristic coloration of the male, with the prominent orange 

 and black spot on the caudal fin." 



