504 KEPORT OF COMMISSIONER OF FTSTT AND FISHERIES. [128] 



liiiv; aii'-liolos at intervals of 110 meteis. Aii-lioles sLoiiUl be made es- 

 pecially in tiie places where the water flows into the pond and on both 

 sides of the pond, so as to procure a current of air under the ice."* 



The number of air-holes should not be excessive, nor should they be 

 too large, because this would deprive the fish of some of the necessary 

 warmth. But, as Reimann says in another place, "Winter ponds, which 

 are fed by a rapidly flowing river, or even by a good spring, will rarely 

 need .any air-holes." 



Horak,f as has already been stated, thinks that air-holes are absolutely 

 necessary ; but as ap])ears from his statement relative to the signs which 

 indicate the approaching death of the fish, air-holes cannot altogether 

 prevent it, as tlie first indication are seen in the existing air-holes, which, 

 so to speak, become i)oints of observation. lie likewise says that air- 

 holes are made in the ice, not merely to i)roduce a current of air, but 

 also to enable the pond cultivator to watch the fish in their winter-quar- 

 ters. According to this author, air-holes in large ponds should be 1) to 

 14 meters long, .8 to 1 meter broad, and distant from each other 17 to 

 35 meters. They should be of considerable size, and be made in gieat 

 numbers, because they are intended to keep up a current of air and act 

 as outlets for vitiated air. llorak thinks that a pon<l will rarely need 

 more than three or four air lioles, unless it is very large. Air-holes 

 should be made as soon as the ice has reached a thickness of 5 to 7 cen- 

 timeters [about L* inches]. 



Tscheiuer has probably hit the nail on the head when ho says: "If 

 proper care is taken to keep the Avater clear and pure, and if the num- 

 ber offish is not disproportionate to the (|uanlity of water and the size 

 of the pond, the safe keeping of the fish may unhesitatingly be intrusted 

 to Mother Nature, who (iares for all beings with equal wisdom." 



The fisheries in the winter ponds take place in spring-, generally in 

 April, an<l are carried on in exactly the same manner as in the rais- 

 ing ponds; but as the number offish will be greater, care should be 

 taken to get through as quickly as possible, and to place those fish 

 which are destined for the raising ponds into these at once. To try to 

 save labor and expense by employing but few men and carts would be 

 a great mistake. In order to carry on the fisheries rapidly and system- 

 atically, the pond cultivator should, during winter, prepare a careful 

 plan for stocking his pon<ls in spring, and the material for such a phni 

 will be furnished by carefully noting down the results of the previous 

 autumn fisheries. As the fish do not receive any food in tlie winter 

 ponds, except what may have been dissolved in the water, they will 

 lose some weight during winter. This loss is generally 2 or 3 per 

 cent, sometimes greater. Wlien the fisheries have come to an end, the 

 ponds should be drained entirely, anti be allowed to lie dry during the 

 summer. If any fish have died in the pond during winter, the pond must 



* Reiniaun, p. IIG. 

 t Horak, Tdclm-irfhsdiaft, 1869. 



