THE GERMAN CARP IN THE UNITED STATES. 627 



little avail, since the places were so large and the conditions so varied 

 that it was practical ly impossible to get the fish out. 



There remain still to be considered those ponds in which the water 

 can be maintained at a definite height irrespective of the varying level 

 of the neighboring waters. Under suitable conditions they could 

 probably be constructed best in valleys and natural depressions 

 according to the plans already outlined as being in general use in 

 carp-cultural establishments. Under the conditions of our fisheries, 

 however, it is a matter of great economic importance that these ponds 

 should be as near to the fishing grounds as possible, and as the land 

 there is low and marsh}" the ponds must for convenience be constructed 

 in or along these marshes. For thia reason the problems presented 

 are very different from those met with in the building of ponds on 

 higher ground. The greatest difficulty comes, of course, in the mat- 

 ter of the drainage of the pond, since its deepest portions of necessity 

 lie below the level of the outside waters. An idea of the methods 

 that have been devised can probably best be conve} T ed by giving brief 

 descriptions of two or three ponds which have now been in use for 

 several years. 



Along the marshy shore of the Portage River, a mile or two above 

 Port Clinton, Ohio, is a successful carp pond covering some 30 to 35 

 acres, and owned and managed by two brothers, who also conduct at 

 the same time a fruit farm immediately adjacent to the pond. The 

 site of the pond was originally a marsh, flooded by backwater from 

 the river, where the carp commonly came in to feed and to spawn. It 

 was first converted into a pond (see diagram, p. 628) by throwing up 

 an embankment along the river side, cutting it off from the river, 

 but still leaving it connected by an open gateway protected by a screen 

 or grating. The inclosed water was at the same level as the outside 

 water, and as the level rose and fell a stream rushed in and out through 

 the gateway. This plan was found to be unsatisfactory, as the 

 impounded fish crowded about the grating, neglecting to feed, and at 

 the same time becoming badly bruised by their contact with the bars. 

 The embankment was then raised and the gateway closed, so that the 

 water in the pond could be maintained at a level 1 to 2 or 3 feet or 

 so higher than the mean level of the river, while at the same time the 

 increased height of the water caused it to spread farther back over 

 the land, enlarging the pond, and encroaching upon a neighboring 

 cornfield, a large portion of which was thus converted into marsh. 

 The principal embankment was easily raised by having a shovel-dredge 

 make a cut along the inner side, the excavated mud being deposited on 

 the outer side of the cut to form the embankment. The lower por- 

 tions were built with a scraper at a time when the river was especially 

 low, at which periods the pond can be practically drained of water. 

 During rainy seasons springs kept the water well up to the desired 



