4 V. S. BUREAU OF FISHERIES. 



to obtain the young fish for distribution to waters they are intended 

 to stock, or for other purposes, can not be accomplished while thick 

 plant growth is present to entangle the fish and interfere with the 

 operation of the seine, and there is thus a periodical necessity of 

 clearing away or at least reducing all gross vegetation. This process 

 is laborious and expensive ; the cost of operating a pond-culture sta- 

 tion is, in fact, largely the cost of this periodic clearance of the ponds 

 and varies with the characteristics of the predominating species of 

 plants. Methods in practice at several stations are described in a 

 later portion of this paper. 



Particular kinds of vegetation may be objectionable also in specific 

 ways other than with reference to the difficulties of removal at sein- 

 ing time. Large-leaved plants may ofler too much shade to permit 

 other plants and the requisite animal life to thrive; plants of per- 

 sistent growth may take possession of the ponds and crowd out 

 species more desirable ; or plants not in themselves objectionable may 

 not be desired because other obtainable plants are more desirable for 

 the same qualities. The question becomes one of control. ^Vher- 

 ever there is soil bottom vegetation is voluntary, springing up im- 

 mediately even in artificial ponds, and any attempt to prevent the 

 entrance by natural agencies of water plants common to a region 

 is fraught with much the same difficulties that are encountered in 

 the attempted exclusion of weeds from a garden. It remains to 

 secure the balance that will bring the conditions nearest to the ideal. 



AQUATIC PLANTS AT THE POND-CULTURE STATIONS OF THE 

 BUREAU OF FISHERIES. 



With its wide geographic range the Government work in pond 

 culture naturally embraces a variety of conditions and affords inter- 

 esting and profitable comparisons. The climate, the quality and 

 temperature of the water, the character of the soil, as well as other 

 factors, make the management of each pond-culture station a sepa- 

 rate problem. The inevitable dependence upon a natural food sup- 

 ply for the young fish, however, concentrates the efforts in such work 

 about the great factor of vegetation and, next to water supply, makes 

 the selection and control of aquatic plants in ponds the most im- 

 portant question with which the pond culturist has to contend. The 

 popularity of the basses, crappies, and sunfishes, moreover, and the 

 feasibility of increasing their numbers by cultivation make pond cul- 

 ture a subject of especial interest to people everywhere in the United 

 States, and the Bureau of Fisheries is constantly receiving inquiries 

 and requests for information. The following notes are therefore 

 thought to have interest and value not only to the professional fish- 

 culturist but to the public generally. They represent efforts to col- 

 lect specimens of all the aquatic plants found at the various pond- 

 culture stations of the bureau, with observations of the respective 

 superintendents as to the particular value of the desirable species and 

 the objectionable characters of the undesirable. It is hoped thus 

 to aid in determining the relative value of each, or at least to afford 

 data that will be useful in future work, at the same time empha- 

 sizing the fact that present knowledge of the subject is all too limited. 

 These notes are not based upon biological or other scientific investi- 

 gation, but are gained from the observations and experience of prac- 



