Fish Production in Lakes as a Guide for Estimating Production in Proposed Reservoirs

Abstract

A LARGE number of artificial reservoirs are being proposed for early construction throughout the United States, which in many cases will have a profound effect on fish and wildlife. It has become imperative, therefore, to attempt to evaluate this effect prior to the completion of construction plans, in order to obtain such modifications in design or water utilization as will assure the maximum benefits to fish and wildlife compatible with other uses and values. This paper touches on only one phase of this evaluation-the quantities of fish that the proposed reservoirs may be expected to produce. Opinions on this subject vary from extreme pessimism to rosy optimism, depending largely on the observers' experience. Admittedly, there is a tremendous difference in the potential yield of various bodies of water, from the 200pounds (or better) per-acre yield of the fertilized, properly-stocked farm pond to the one-pound-per-acre yield of Lake Superior. Yet it is possible to create a useful yardstick by studying observed production data. Such a measure of yield, based on actual experience, is bound to give a more reliable estimate than pure guesswork. There are two types of data available on the populations of fish in lakes and ponds: total populations and annual yields. Unfortunately, both types of data are rarely available for the same body of water. Total population data are available only for small lakes and ponds, chiefly ones in which the fish have been poisoned. Generally speaking, only those ponds have been poisoned whose populations were abnormal in some respect. Either the natural balance between the larger predators and the smaller fish had been upset in such a manner that the lake was crowded with stunted panfish, or the lake had become heavily populated with carp, buffalo, or other rough fish, to the detriment of more desirable species. Obviously, the data from these atypical lakes are not truly representative of the average lake; but being the only data available they are presented for what they are worth. Statistics on the arinual yield of lakes are better than those on total populations because they usually refer to lakes with more or less normal populations. All the available literature on lake production has been examined, and the pertinent data compiled as shown in Table I. However, it was necessary to omit, for various reasons, certain ponds and lakes from consideration. For instance, the annual yield for Standard Lake (16.0 acres) given by Beckman (1941) referred to fish stocked immediately after the poisoning of the entire population, and thus does not represent the yield from a normally balanced population. Cahn (1939) gives the weight of carp taken from Neosha Mill Pond in southern Wisconsin, but not the area of the pond. A preliminary creel census of the trout catch in Fish Lake, Utah, given by Hazzard (1935) is omitted since the study covered but 13 days. Total yields from certain