528 REPORT OF COMMISSIONER OF FISH AND FISHERIES. [62] 



the reasou tliat these latter are more aj^t to freeze tlirougliout during 

 ])articularly severe weather than large ones. In small ponds, moreover, 

 the snow-water, daring a tha^v, increases the quantity of water so sud- 

 deuly that the fish are scared away from their resting-place, leave it, and 

 suffer injury during succeeding frosts. 



According to Horak, a large pond farm, intended to keep 60,000 to 

 90,000 fish, needs a pond area of 23 to 34 hectares, and a fish-pit, free 

 from mud, of 8.6 to 11.4 hectares.* Jokisch characterizes a good and 

 safe winter pond as follows : " It should be of sufiicient depth so that, 

 even during the most severe frost, it does not freeze to the bottom, but 

 always retains an ample quantity of water. Winter ponds should not 

 be exposed to floods occasioned by sudden thaws, for as soon as the fish 

 notice an unusual motion in the water, they become excited and rise 

 towards the surface, where they freeze to the ice and die. Tliis is par- 

 ticularly dangerous in spring when a thaw is often succeeded by a severe 

 frost. Winter ponds should be in a quiet locality, and during winter 

 there should be no walking, sleighing, or skating on them, nor any 

 knocking on the ice. Winter ponds ought, therefore, never be used for 

 furnishing ice for ice-houses, because the cutting of the ice would seri- 

 ously disturb the fish. The fish need a little air, especially when the 

 snow is very deei), and to sui)ply this a hole should be made in the ice, 

 in which are stuck some bundles of reeds or straw, which reach down 

 into the water and protrude above the ice. Whenever a pond has a^ood 

 many reeds, air will naturally be supplied, and it Avill not be necessary 

 to make a hole in the ice. Nothing, however, contributes so much to 

 the success of a winter pond as springs, or a supply of spring water." t 

 Horak also insists that the winter ponds should be near to the stock 

 ponds, so as to i^ake the transportation of fish easy, and that prior to 

 being filled they should be sowed at least in part.* As regards the 

 jn'oximity of the stock ponds, it is of course desirable, but in selecting 

 winter ])onds this consideration should not be decisive. 



5. THE RELATIVE SIZE OF THE DIFFERENT CLASSES OF PONDS. 



In a well-regulated pond farm the size of the spawning and raising 

 ponds should be proportionate to that of the stock ponds, i. c. the 

 former should always be ready to supply the necessary stock of fish of 

 the required quality'. To make this proportion correct is the first con- 

 dition of successfully cultivating a given pond area, and of deriving 

 from it the greatest possible income. If the proportion between the 

 raising and stock ponds is not correct, this may give rise to difticulties, 

 if there are in the raising ponds more young fish than can in two or 

 three years be developed to marketable fish in the stock ponds ; and, on 

 the other hand, if the raising ponds cannot furnish the number of fish 



? Horak, Teichwirthschaft, 1869, 



t Jokiscli, Handbuch der FiscJierei , 1804. 



