I 



33 



Tiles and boards can be placed in the ponds at a depth 

 of 8 inches to 3 feet. These fishes prefer a board, 

 rocks, tile fragments of flower pots, or stones close 

 to a sandy shoal, beneath which the male digs a nest 

 and the female lays her eggs (fig. 11). 



POND PRODUCTION 



Months of preparation, fertilizing, and feeding 

 culminate in the harvest of minnows, usually in the 

 fall. In order that the minnow-culturi st might gain 

 some idea of the yield to expect from his ponds, data 

 have been gathered on pond yields in Michigan, Wiscon- 

 sin, Minnesota, and in West Virginia, where controlled 

 tests were conducted. Tables 3 to 6 show that yields 

 vary greatly with the species raised, geographic location 

 of the pond, source and temperature of water, nature 

 of the bottom, stocking rate, and the amount and kind 

 of fertilizer used. Costs and returns likewise vary. 

 It has been found in Minnesota that though almost as 

 many fish are produced in some large ponds as in small 

 ones, the actual yield declines with increasing pond- 

 size. In large ponds, the fish are there but only a 

 part of them can be harvested: the effectiveness of 

 successive seine hauls decreases because of the scat- 

 tering of fish between hauls and the general thinning 

 of the population. 



The Minnesota production table illustrates some 

 of the difficulties in raising minnows. Pond No. 1 

 was not stocked heavily enough "for maximum production. 

 Fifty percent of the harvested fish, however, were of 

 large size. Pond No. 3 could not be seined easily; so 

 only a part of the production could be harvested. Pond 

 No. 5 illustrates the poor production obtainable where 

 a predator population is able to live through the 

 winter. Pond No. 8 did not have sufficient screening 

 at the outlet: the suckers could escape into the lake, 

 and northern pike were able to move into the pond. 

 Nos. 1 to 8 were operated by hatchery men who had years 

 of experience in raising trout and wall-eyed pike but 

 had not raised minnows before. The beginner in minnow 

 propagation can expect low returns unless he understands 

 the requirements andthe best methods of propagating the 

 minnows he desires to raise. 



Two Minnesota ponds demonstrate the effect of 

 stocking and fertilization on the pond yield. A 5-acre 

 pond stocked with 350 golden shiners (70 per acre) was 

 fertilized with 4,650 pounds of commercial fertilizer 



