Effects of Fin-Clipping on Mortality and Growth of Yellow Perch with a Review of Similar Investigations

Abstract

Fin-clipped and control young-of-the-year yellow perch (Perca flavescens) were held in a hatchery pond for a year. Survival did not differ among controls and fish which had a left pectoral, right ventral, or both ventrals clipped but survival was lower in those with an anal fin clip. Growth did not differ among controls and clipped perch except in those with a left pectoral clip, which were smaller. Hence, survival and growth did not appear to be related. This and other studies indicate that fin-clipping reduces survival in fry, may or may not affect survival and growth of fingerlings, and has little effect on larger fish. Various investigations have provided little evidence that predation is an important source of excess mortality among fin-clipped fish. Fin-clipping is a valuable and widely used method of obtaining various kinds of information about fish, and it is commonly employed with the untested assumption that clipped fish do not differ otherwise from their untreated counterparts. False conclusions can be drawn from studies involving clipping if this assumption is not valid. Short-term mortality, including that brought about by physical injury, can be identified by holding treated fish for a short period before release. It has not usually been found a source of excessive losses (Parker et al. 1963). Long-term effects of fin-clipping may be more important and may go unnoticed (Ricker 1949:29-30). To determine the effects of fin-clipping on yellow perch, growth and survival were measured for fin-clipped and control fish held for a year in a hatchery pond. It appears that some clips did influence growth and survival of the fish, and these results are discussed and compared with those of other studies. I thank Stan Brown, Sandfield Hatchery Manager, for wholehearted cooperation throughout the experiment, and Gordon Thomas for help with the draining of the pond and removal of the fish. John Dobell collected and identified plankton in August, 1965. Dr. F. E. J. Fry, Dr. J. C. MacLeod, and W. J. Christie, director of the Glenora Fisheries Station, read the manuscript. METHODS AND MATERIALS Yellow perch, predominantly young-ofhe-year, were seined along the shore of Lake Mindemoya, Ontario, an inland lake in Manitoulin Island (45045' N; 82010' W). They were placed in fry tins and transported 20 miles to the South Bay Fisheries Research Station and left in the tins in running water until they could be treated, a period of 6 hours to 2 days. They were anesthetized with MS 222, some were measured, and the young-of-the-year were given one of five treatments: a left pectoral (LP), right ventral (RV), both ventral (BV), anal fin clip, or no clip (control). The perch were treated in rotation, and any that did not appear normal were rejected. Following treatment they were held in running water for 6-24 hours, so that the few handling mortalities could be removed, and then were taken 10 miles to the Sandfield Fish Hatchery and put i a pond. From August 20-25, 1964, 133 young-ofthe-year perch were captured, measured, treated, and planted. On October 20-23, 1964, 2,222 were captured, treated, and planted, but only 750 of them were mea1 Contribution No. 66-16 from the Ontario Department of Lands and Forests, Research Branch, Maple, Ontario.