624 REPORT OF THE COMMISSIONER OF FISHERIES. 



effects oi it after passing, together with the large estate of a rich monastery of the 

 same name, in the year 1670, into possession of the Princes of Schwarzenberg, their 

 present owners. The extent which carp-culture has reached on these princely 

 domains will be seen from the circumstance that their artificial ponds comprise an 

 area of no less than 20,000 acres. The proceeds amount to about 500,000 pounds of 

 carp per annum. The ponds of the Princes of Schwarzenberg are probably the most 

 extensive of the kind on the globe. They are usually situated in some undulating 

 lowland country, where small valleys have been closed in by gigantic dams for the 

 purpose of forming reservoirs. Similar establishments, though not equally exten- 

 sive, are found in the provinces of Silesia and Brandenburg; as, for instance, near 

 Breslau and Cottbus, in Peitz and Pleitz, which 1 visited last year. In Hesse-Cassel, 

 Hanover, Oldenburg, Mecklenburg, and Holstein there are also many hundreds of 

 ponds, none of them covering more than a few acres, but almost every large farm 

 possessing at least one of them. 



The well-appointed carp-cultural establishment has at least three 

 kinds of ponds, each adapted for a particular phase of the industry. 

 These ponds are usually made by throwing dams across small vallej^s, 

 and by the aid of dikes, and are commonly fed by small streams flow- 

 ing into them, by springs, or they may depend entirely upon the 

 rains to keep them tilled. These last are often spoken of as "sky- 

 ponds," and are much more uncertain than the others. The ponds 

 fed b}^ streams are ordinarily protected from flooding by freshets by 

 leading the main channel of the stream ai'ound them, so that the 

 amount of water which flows into the pond can be regulated at will. 



The classes of ponds are: 



1. Spawning ponds. Shallow ponds in which the water is easily 

 warmed by the sun, and suitable for the spawning fish. 



2. Raising ponds. Ponds, usually of medium size, to which the fry 

 are transferred and where the}^ are retained, isolated from the larger 

 fish, until they are a year or two old. 



3. Stock ponds. Large ponds in which the fish are kept until they 

 have reached a marketable size; this is usually considered to be when 

 they have reached a weight of 2i to 2i pounds. One reason that the 

 young fish are reared for a time in the raising ponds is that in the 

 stock ponds with the older carp are often kept a number of predaceous 

 fish, such as perch, pike, etc., which are supposed to keep the carp in 

 better condition by preventing them from becoming too lazy and seden- 

 tary. These fish would destroy the carp fry if the latter were put 

 into the stock ponds while still small. The predaceous fish also form a 

 secondar}' source of income. 



Since the stock ponds are not always favorable for the wintering of 

 the fish there are sometimes ponds especially adapted for this, and 

 these are known as — 



4. Winter ponds. These should be in sheltered localities, if possible, 

 and should have a depth of at least 6 to 8 feet. 



All the above classes of ponds are constructed upon the same general 

 principle. Ditches f j'om the various parts of the pond lead into other 



