During the time of water covering, sluice boards are to be set in above the projecting 

 Eckstein sieve box, up to the rim of the sluice. The sluice is to be locked against theft 

 by means of a cover to be placed on top of the side wall (Fig. 10)» 



The costs of pond construction are mainly the combined costs of the sluice and of the 

 dam construction. The ready cut wood for a sluice of pine wood with a vertical shank of 

 2.5 meters height and a horizontal shank of 5 meters length cost in 1931 about ^0 national 

 marks. EiLght to ten working hours were required to put it together. The durability time 

 is about 25 to 30 years. The amount of earth to be moved, which is equal to the amount of 

 the dam, is easily calculated as the product of the cross section area and length of the 

 dam. Vdth an incline of 1:2 on the jjiside, the cross section of the normal dam for a 

 pond of 1 meter depth (the height a = 1.30 meters and a crown wiflthof about 30 cm.), is 

 approximately 



Q = a 1 i^a (a 1 0.30) - 1.30 1 5.20 x 1.60 

 2 2 



- 6.50 X 1.60 =5.2 square meters. 

 2 



The mass of earth in cubic meters is obtained by multiplj-liig by the length of the dam. 



Chapter III 

 T^rpvr-. A!\'n STZK C' PQiin FISHKRIi?.5 

 Pond fishery (Pisciculture) is divided into two main branches; 



(1) Carp fisheries, also frequently called Carp and Tench Fisheries, are conducted 



in shallow ponds (of about 1.30 meters depth) of warn water (in su-tuner 20 degrees centigrade 

 or higher) vjith little or no "through current". Since carp — and also tench — require large, 

 "natural feeding grounds", their ponds are always relatively large and less stocked with 

 fish than trout ponds, even when conducted upon an intensive scale. Carp and tench culture 

 is mostly conducted upon large areas, periodically flooded and by exploiting their natural 

 productivity. 



(2) Trout fisheries , requiring even under intensive culture only small ponds but 

 with a strong "through current". Brook-like ponds, rather long are best suited since 

 trout are raised almost exclusively by artificial feeding. The pond is for them only a 

 stable, an abode, so to speak. The "cultivation" of the pond as well as the exploitation 

 of the natural productivity of the pond play practically only a secondary role. 



The water of the masting ponds must be cool, 1 to 2 meters deep and even on hottest 

 summer days below 20 centigrade. V.'e find trout fisheries therefore mostly in the regions 

 of secondary mountain chains and in plains, near springs. Aside from ponds, trout fish- 

 eries require hatchery troughs and natural waters (brooks) for the rearing of the spavin. 

 Trout fisheries therefore extend beyond the territory of "pond culture", 



Fro.fi the foregoing it is obvious that carp and tench culture on the one hand, and 

 trout culture on the other are two distinctly different branches of pisciculture. We 

 even find quite a distinction between trout breeders and ordinary fish-pond keepers. 



Trout culture is more frequently found in Hannover, HVestphalia, the Rhineland, 

 Hessla and in Southern Germany, irtiile carp fisheries will be found foremost in Silesia, 

 Bavaria, Saxony and in Brandenburg, 



The distinction between the tvro classes of fishbreeders is even outwardly apparent. 

 There is an Association of German Fishbreeders and an Association of German Trout Breeders. 



Through an Ordinance of January 5, 1931, the Prussian Department of Agriculture, 

 Estates and Forests has created — ^with regard to trout culture — the three classes of pond 

 apprentices, of helpers and of pond masters. This in itself denotes a higher development 

 of this brand of pisciculture in comparison with other branches. 



69 



