680 REPORT OF COMMISSIONER OF FISH AND FISHERIES. [8] 
250 carp of one summer, a Spawning-pond of 1 hectare would be sufficient 
to completely stock with carp an open water area of 1,000 hectares in 
5 years, and to fill up the gaps occasioned by the fisheries. 
In setting out the young fish, they should be distributed, as much as 
possible, over the entire water area, and care should be taken to place 
them in shallow water where they find plenty of food and where they are 
protected from fish of prey. 
If it isintended to raise large carp, which are not exposed to any dan- 
ger from fish of prey, a larger pond area is needed. I must here refer 
once more to Mr. Gasch, whose results are unexcelled by those of any 
other pisciculturist, and, basing my assertions on his experience, I must 
say that it requires a pond-area of at least 50 hectares to raise 50,000 carp 
of 20 centimeters length per annum; therefore, 50 times as many as 
we supposed before. 
The otter is an exceedingly dangerous enemy to the fish, and must 
positively be exterminated, if carp are to be raised; herons, cormorants, 
and ducks also do great damage to the spawning-ponds. It is, therefore, 
necessary to combat these enemies in the most energetic and persistent 
manner. Inmy book Fischzucht I have treated of all these matters at 
length, and any of my readers who desire further advice on this subject 
are therefore referred to that work. 
