Recently in trout culture the operation of larger ponds and the utilization of 

 their natural productivity for brood raising and growing spavm trout has become very 

 important, 



Tfithin the two main branches, many flshbreeders go in for diversified industries 

 and some side lines. Carp and tench breeders often also raise Gold Alands at the same 

 time, while brook trout culture is often combined with the culture of rainbow-trout, 



UTe can furthermore disting\iish between them 



(1) Extensive management of a fishery, where, according to the definition 

 of Aerebosic the individual fish enjoys relatively much space within 

 the pond, and 



(2) Intensive management, where the individual fish lives with relatively 

 restricted space, and where its existence is guaranteed more through 

 artificial feeding, fertilizing and more general care of the pond than 

 through prevailing natural conditions. 



Small secondary industries, since they must be simple, must be essentially extensive 

 or half intensive. The general division of the industries into secondary and main 

 industries does not mean much, since even very large industries are often the secondary 

 industries of still larger agricultural industries. 



On the other hand, the distinction is important between 



(1) Fisheries proper, where fish are raised and cultivated from eggs to 

 adults, and 



(2) Partial fisheries which specialize in only certain classes (grades) 

 of fish, according to age or size. 



Carp-growing industries are preponderantly full industries. Small secondary industries, 

 with few exceptions, must always be special industries which are concerned only with carp 

 growing or trout growing and produce only food fishes (see section XIII). The very large 

 pond industries which produce mainly food carps and food trout, must often buy larger 

 additional amounts of stock to add to the stock material they have raised. 



In table 10, we have a classification of the different fisheries (in Germany), their 

 size and number, according to figures by Rlihler, K. Schiemenz and Jaisle, 



Table 10. 



Carp Fisheries 



Trout Fisheries 



Size of the 



individual 



fishery 



Number of 

 fisheries 



Pond area 



in 



Germany 



In 1925 



Annual production 



of adult trout 



by the individual 



fisheries 



Number of 

 fisheries 



in 

 Germany 



"Dwarf" and small 



fisheries 



<10 



hectar 



10,000 ha 

 (16.5^) 



^10 dozen 



600 



Average fisheries 



10 to 500 

 hectars 



800 



37,500 ha 

 (62.5^) 



10 to 

 100 dozen 



100 

 (13.95S) 



^^^•rt:^"'"> 500 hectars 15 



Fisheries 



12,500 ha 

 (21^) 



7 100 dozen 



20 

 (2.8^) 



60,000 ha 



720 



70 



