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Usinger: Introduction 



By way of summary it should be emphasized that 

 wastes are not intrinsically bad. In many cases they 

 are legitimate by-products of man's civilization. 

 Too often industrialists try to ignore pollution prob- 

 lems by "looking the other way" and conservationists 

 would simply legislate them out of existence. The 

 result is an impasse and the solution, of course, lies 

 not in either extreme but requires that issues be 

 faced squarely and dealt with on a continuing basis. 

 Actually, substantial progress has been made in 

 recent years by recovering useful chemical wastes, 

 improving erosion control, and by increased knowledge 

 of the processes involved in reduction of organic 

 wastes by natural waters. It is now realized that 

 organic wastes simply speed the process of eutrophi- 

 cation in a lake or stream. In limited or controlled 

 amounts they increase the productivity of natural 

 waters. It is only when an excessive load is dumped 

 at a time or place which affects the interests of 

 other people that trouble starts. At such times the 

 limnologist is usually called upon to provide evidence 

 for or against pollution. 



Pond Fish Culture 



Aquiculture has been practiced since the dawn of 

 history and has been a source of protein in China 

 and India for centuries. Strictly from the viewpoint 

 of productivity in pounds per acre, carp are unsur- 

 passed, yielding up to 3,000 pounds per annum in 

 the Orient. However, in the United States carp are 

 not considered desirable for human consumption, and 

 fish ponds are not intended solely for food production. 

 They may be purely aesthetic garden ponds, primarily 

 practical farm ponds for watering stock, or recrea- 

 tional pools for fishermen. In California there has been 

 increased interest in the multipurpose farm pond and 

 in commercial "trout farm" ponds where fishermen 

 are guaranteed results and pay for their catches by 

 the linear inch or pound. 



Experiments in Alabama (Swingle and Smith, 1941) 

 have shown that each pond has a normal carrying 

 capacity for a particular species of fish, regardless 

 of depth (18 to 54 inches) and regardless of number of 

 fish stocked. If a pond is overstocked, the fish will 

 be small, if understocked, they will be large; in either 

 condition the pounds per acre will be the same. 

 Phytoplankton feeders such as goldfish yielded up 

 to 1,000 pounds per acre; insect feeders such as 

 bluegill, 600 pounds per acre; and fish feeders such 

 as large-mouthed black bass, 200 pounds per acre. 

 Ideally, a pond should be stocked with a ratio of 

 carnivorous and forage fish of approximately 1:10 

 or 1:15. 



The total productivity of a pond can be increased 

 by addition of fertilizer. The following mixture is 

 recommended: 40 pounds of sulfate of ammonia, 60 

 pounds of superphosphate (16 per cent), 5 pounds of 

 muriate of potash, and 15 pounds of finely ground 

 limestone per acre. The materials should be mixed 

 before applying. Fertilizer was applied in Alabama 

 (Swingle and Smith, 1951) beginning in April or May 



and continuing every four weeks until September or 

 October. Thus eight to fourteen applications were 

 made at an annual cost per acre of $11.00 to $20.00 

 or 3 to 6 cents per pound of fish. The stocking policy 

 of the U. S. Fish and Wildlife Service for new farm 

 ponds in the southeastern states is: 50 bass and 500 

 bluegills per acre in unfertilized waters, and 100 

 bass and 1,000 bluegills per acre in fertilized waters 

 (Holloway, 1951). 



Weeds are generally considered to be undesirable 

 in fish ponds. They supply protection for mosquito 

 larvae, hinder bass from their essential role in pre- 

 venting an overpopulation of plankton and insect- 

 feeding fish, utilize fertilizer without greatly increasing 

 food for fish, and interfere with sport fishing. To 

 prevent the rooting of weeds along shore lines, the 

 edges of ponds should be deepened. Periodic clearing 

 also may be necessary to remove volunteer plants 

 before they become heavily rooted and spread (Davison 

 and Johnson, 1943). 



The role of insects in farm ponds was studied 

 intensively by Wilson (1923) in Iowa. It was found, as 

 might be expected, that insects are an important 

 element in the food of pond fishes and that they are, 

 in turn, dependent on phytoplankton and other organic 

 matter for their existence. However, a special situa- 

 tion exists for predatory insects in farm ponds. 

 Immediately after stocking, all the fish are small 

 and hence are at the mercy of the larger insects, 

 with no fish yet large enough to eat them. The beetle 

 genera Dytiscus, Hydrous, and Cybister, Belosto- 

 matids, and large nymphs of Odonata are especially 

 troublesome in ponds with fish fry but seldom bother 

 fish more than one year old and, in fact, are a valuable 

 source of food for the larger fish. Therefore it is 

 recommended to: screen small ponds for fish fry in 

 areas where large predatory insects occur in abun- 

 dance; remove strong lights from the immediate 

 vicinity of ponds since the large predators are 

 attracted to lights; remove fry from infested ponds 

 and stock with larger fish; and remove fry and drain 

 infested ponds, thus exposing large predators so 

 that they may be destroyed by hand. Chemical control 

 has been recommended by Meehean (1937), using oil 

 film at the surface (1 part cod-liver oil to 3 parts 

 kerosene, or straight kerosene at 10-12 gallons per 

 acre), but this has no effect on the gill-breathing 

 immature insects which take oxygen beneath the 

 surface. 



A purely negative approach is not adequate for 

 proper management of insects in pond fish culture. 

 By far the majority of aquatic insects are desirable 

 and should be maintained at high population levels. 

 Fortunately, insects need not be stocked because 

 they migrate readily from one pond to another. Wilson 

 (1923) found eight species of beetles in a new pond 

 twenty-four hours after it was filled with water and 

 five more species invaded the pond after three days. 

 In ponds where predation by fish is so intensive that 

 insects cannot maintain themselves, fish-free side 

 ponds or troughs may be used. In this way stocks of 

 insects can be developed and washed into fish ponds 

 periodically as needed. 



