. The changing Illinois environment : critical trends : technical report of the Critical Trends Assessment Project. Man; Pollution; Environmental protection; Ecology; Environmental impact analysis. Figure 5. Changes in the number of angler-days spent on recreational fishing at various Illinois lakes according to a mail survey conducted every three years by the Illinois Department of Consen'ation. Values are expressed as the percent change relative to the number of angler-hours spent at each group of lakes in 1977. Absolute values are not given because these are inflated by nonresponse and reca
. The changing Illinois environment : critical trends : technical report of the Critical Trends Assessment Project. Man; Pollution; Environmental protection; Ecology; Environmental impact analysis. Figure 5. Changes in the number of angler-days spent on recreational fishing at various Illinois lakes according to a mail survey conducted every three years by the Illinois Department of Consen'ation. Values are expressed as the percent change relative to the number of angler-hours spent at each group of lakes in 1977. Absolute values are not given because these are inflated by nonresponse and recall biases (Tarrant et al. 1993); the relative changes shown here assume that these biases were consistent among years. "Other lakes and impoundments, " which include state conser- vation lakes, public lakes, organizational lakes, daily fee lakes, and private lakes, are subject to the majority of the total angling effort. have increased since the 1970s (Figure 9). Part of this is a response to increased fishing pressure, part is due to the stocking of new or reconstituted lakes, and part is due to a desire for particular coolwater species such as walleye and muskellunge that have limited repro- duction because of inappropriate environmental conditions. None of these species programs has been been adequately supported by additional license charges—even for salmonids, for which an additional fee is charged—although modest modest fee increases were instituted in 1979 and 1982 for hatchery invest- ment and stocking. Expenditures on fish production for stocking (including hatcheries) have constituted 33% of the total operating budget of the Division of Fisher- ies of the Illinois Department of Conservation (Illinois State Budget Detail, Fiscal Year 1992) for the past seven years. Therefore, evaluations of the cost- effectiveness of various rearing and stocking strategies need to be related to angler demand for these fish species. These estimates need to be compared with
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