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Use of Nets to Control Fish Populations The use of nets and traps has met with different success because an inadequate fraction of the population is removed. Large escapement in large lakes require continuous fishing for satisfactory control. Some nets are effective only in shallow waters (e.g., fyke nets). In deeper waters, these nets do not fish well since fish can swim over the "leads." Seines and trawls have promise for control in some waters but require a relatively smooth bottom, free of snags to be fished properly. This condition is found only occasionally in most waters. In small farm ponds with a suitable bottom, seines can be very effective in catching fish. Wing nets and trap nets are also effective for crappies, sunfish, bullheads, and gizzard shad in shallow waters. The use of gill nets and trammel nets are effective on many species of fish. With the exception of the seines and trawls (active gear - moved by humans and does not require fish movement to be effective), trap nets, gill nets, and trammel nets are passive gears that depend on fish movement. At certain times of the year, passive gear can be effective in catching certain species. The main drawback in using nets is that they are labor intensive and are rather expensive. Case Histories Using Chemicals in Combination with Nets Often catches in passive gear will be largest at the beginning of the netting operation when the gear will catch fish that are active. Sometimes the use of a chemical (e.g., copper sulfate) has been used to activate fish increasing net catches (Brown, 1964; Tompkins and Bridges, 1958). Tompkins and Bridges reported that 6 fyke nets were set in Lake Quanopowit, Massachusetts on August 12 and by August 21 the catch per net day had declined from 148 pounds to 11 pounds. On the latter date, the city water commission applied copper sulfate to the pond (as an algaecide) using a concentration of 1.0 ppm. The following day's lifts contained 173 pounds of fish per net, the highest 24-hour return recorded during the entire operation. From this peak, the catch declined to 15 pounds per net day on the 28th when the nets were removed. The application of copper sulfate produced an increase in total harvest between 36 to 45 percent depending upon the extrapolation of what the catches might have been if the chemical had not been used. Brown (1964) stated that his catch was slightly more than double when copper sulfate (0.5 to 3 ppm) was used during 32 nettings on 20 Ohio Lakes. The cost of the chemical and the time required to apply it was considered to be insignificant. Case Histories of Haul Seining Huish (1959) summarized the use of a haul seine in Lake Reedy, Florida from April 1952 to February 1954. 353 seine hauls were made using a 1,100-yard seine. During the seining period, 454,447 pounds of fish were captured and 357,947 pounds of fish were removed from the lake. Gizzard shad, bluegills, redear sunfish, bullheads, and white catfish were removed from the lake in that order while largemouth bass were returned. The removal of these fish (107 pounds per acre) did not produce significant changes in the remaining fish populations except for bluegills. There was a rapid increase in the weight of individual bluegills during the first seven months of the study. The average weight of largemouth bass increased during 2