NATURAL PONDS 



NATURAL PONDS 



In some localities, the bait dealer 

 will have to use natural ponds for 

 the production of minnows because 

 of the lack of suitable locations for 

 artificial ponds. While natural 

 ponds often do not produce as many 

 minnows to the acre as do artificial 

 ponds, there are some points in their 

 favor. Natural ponds do not re- 

 quire expensive dams and control 

 structures, rentals are usually low, 

 and little or no fertilizer is needed. 

 As these factors add up to low pro- 

 duction costs, the margin of profit 

 is usually high. 



Natural ponds available for the 

 production of minnows vary 

 greatly in size and shape, but me- 

 dium-sized ponds are most practical 

 to operate. Large ponds are too 

 difficult to seine and small ponds 

 cost more per acre to seine than do 

 medium-sized ponds. Deep ponds 

 produce better in hot, dry years 

 when shallow ponds become too 

 warm and may even dry up, but in 

 cold, wet years, the shallow ponds 

 come into their own. As it is diffi- 

 cult to predict a full season of 

 weather, the dealer should try to 

 operate both shallow and deep 

 ponds each year. While the type of 

 pond most practical for production 

 varies with the species of minnow 

 to be raised, Minnesota dealers have 

 found that natural ponds 3 to 5 

 acres in size and 5 to 8 feet deep are 

 most profitable. 



Natural ponds vary greatly in 

 fertility. Ponds located in rich 

 farmland are usually very fertile. 



and ponds on poor, rocky soils are 

 infertile unless the runoff includes 

 such sources of fertility as barn- 

 yard drainage. The type of soil on 

 the pond bottom has a definite effect 

 on pond fertility. Fine-textured 

 soils that cloud the water easily and 

 give up their fertility readily are 

 usually found in fertile ponds. 

 Soils that have most of their fer- 

 tility tied up in vegetation or or- 

 ganic matter give up that fertility 

 very slowly and ponds with such 

 soils tend to be moderately fertile. 

 The relative fertility of a pond can 

 be judged by how green it becomes 

 during hot weather: the greener 

 tlie water, the richer the pond. 



A rich pond will contain a large 

 amount of nutrients in the water 

 and will produce good crops of wa- 

 ter fleas for fish food at various 

 times during the season. Such a 

 condition is desirable for the pro- 

 duction of large fish crops, but rich 

 ponds also may produce great 

 amounts of algae. P]ven though al- 

 gae enter into the food chain, these 

 microscopic plants are not readily 

 eaten by most minnows, and when 

 they decompose the dissolved oxy- 

 gen in the water is used up and 

 large amounts of ammonia are pro- 

 duced. The fish need a fairly high 

 concentration of oxygen for respira- 

 tion, and ammonia in large concen- 

 trations is toxic to them. Conse- 

 quently, the decomposition of a 

 heavy algal growth may kill a large 

 number of fish. Algal blooms are 

 likely to be more harmful in shallow 

 ponds than in deep ponds. Some 

 species of minnows tolerate lower 



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