Growth Rates of Yellow Perch, Perca Flavescens (Mitchell), in two North Dakota Lakes After Population Reduction with Toxaphene

Abstract

Fishery waters overpopulated with desirable species generally produce few harvestable fish because of slow growth rates. In 1962 Bennett stated that no fish of harvestable were found in some waters thus affected. Eschmeyer (1936) made a similar observation concerning overcrowded populations of yellow perch (Perca flavescens). For lack of more efficient remedial measures the use of piscicides has been recommended to reduce the numbers the numbers of the problem species. Relatively low toxaphene concentrations in two North Dakota lakes substantially reduced the density of the yellow perch population the effect on other fish species was less obvious. The results reported (Henegar,1961) were incidental to the determination of the minimum toxaphene concentration necessary for fish eradication in that state. The present study was initiated in 1960 to determine the growth rates of the yellow perch surviving in Brush and Long lakes, and thus gain information concerning the suitability of toxaphene tor reducing the numbers of fish in overpopulated waters. The scale method was employed to calculate the growth rates of Brush Lake fish for the 1960 and 1961 growing seasons. Post-treatment growth rates of Long Lake fish were determined tor part of the 1960 growing season and. for all of the 1961 season. Several authors reporting the use of rotenone to thin overcrowded populations or to restore balance between fish species considered the results to be favorable. Beckman (1941) noted that the growth rates of fish surviving the treatment of one-half of Booth Lake, Michigan were too great to be accounted for by normal variation. Substantially increased harvests, apparently the results of accelerated growth rates of remaining fishes, were reported by Swingle, Prather, and Lawrence (1953) subsequent to the poisoning of some Alabama ponds. Hooper and Crance (1960) stated that the use of rotenone was an affective and economical method to restore balance to certain fish populations. Reports of unfavorable results rotenone, or of similar use of other pesticides, were not found. However, the use of toxaphene was recommended by several authors including Hemphill (1954) who first used the chemical for fish eradication. The cost of fish eradication with toxaphene is approximately 15 per cent of the cost with rotenone. On the basis of recommended concentrations and methods for thinning overcrowded fish populations with these chemicals, the use of toxaphene would be even more economical. Definite information relevant to this use of this poison and the subsequent results is conspicuously absent. [Introduction – -page 1-2