YELLOW PERCH OF LAKE ERIE 



211 



release enough legal-sized perch to affect materially 

 Ihe total yield. Since Van Oosten (1932) showed 

 that trap nets \vith a mesh larger than that em- 

 ployed in the nets at the present time did not 

 release perch of 8% inches (present legal size limit) 

 and larger, the reduction in take in 1936-47 un- 

 doubtedly was largely the result of a decrease in 

 abundance of perch rather than a decrease in 

 fishing intensitj-. 



A precise evaluation cannot be made of the 

 changes in abundance of the yellow perch in Lake 

 Erie during the period of greatest fluctuations in 

 yield, because the data are not sufficient. An 

 appro.ximation of the abundance may be obtained, 

 however, from the records of the W. D. Bates 

 Fishery, Rondeau, Ontario, which give the number 

 of pound nets fished and the catch each year for 

 the period 1900-1940, and from those of Leonard 

 Bickley, Sandusky, Ohio, which give the catch by 

 trap nets of a 1-boat fisherj- during the years 191 1- 

 3 1 . The records of number of nets fished and total 

 pounds of fish taken published by the former 



Ontario Department of Game and Fisheries also 

 are of value. 



Although there are certain discrepancies among 

 these three sets of data, they all suggest that the 

 period 1928-35 was one in which the abundance 

 of yellow perch in Lake Erie was high, and all 

 data are consistent in showing that the abundance 

 declined sharply in 1936 and has remained at a 

 relatively low level since that time. Bickley's 

 data, in contrast to those of Bates, suggest a slight 

 increase in abundance in 1921-27, thus indicating 

 that the slight rise in production in the Ohio 

 waters in those years may, in part, reflect abund- 

 ance. 



It must be recognized tliat the j'ellow-perch 

 fishery in Lake Erie is not in a prosperous con- 

 dition at the present time. That the fishery has 

 not collapsed entirely is perhaps a tribute to the 

 fecundity of the perch. The danger exists in the 

 absence of a reserve supply, as well as in the low 

 abundance. The failure of only two successive 

 year classes would lead to collapse of the fishery. 



MATERIALS AND METHODS 



Materials for this investigation on the age and 

 growth of yellow perch were collected at the follow- 

 ing Lake Erie ports: Port Clinton. Sandusky, 

 Huron, Vermilion, Lorain, Ashtabula, and Conne- 

 aut, Ohio; Erie, Pa.; and Dunkirk, N. Y. (See 

 fig. 2.) Originally a separate analysis was made 

 of the data for yellow perch from the western, 

 middle, and eastern sections of the lake; it was 

 found, however, that a combination of the data 

 was justifiable. It was found also that the data 

 for trap nets and pound nets could be combined. 



Table 2 shows, for each type of gear, the number 

 of specimens on which this study has been based. 

 The 1927-37 materials used in the growth-rate 

 studies, a total of 3,036 fish, were random samples 

 of the trap-net and pound-net catches taken during 

 the latter part of the collectmg period of each year. 

 Samples from impounding nets were used because 

 that tj'pe of net is less selective than gill nets, and 

 because the impounding-net collections covered a 

 greater period of years. The 1,341 fish taken from 

 trap nets in the years 1943-48 were used in the 

 study of ammal fluctuations in growth. The ages 

 were determined of 430 specimens taken in com- 

 mercial gill nets during 1927 ami 1928, and of 

 1,136 fish taken in the j^ears 1943-48. The 

 1927-28 material consisted of random samples 



955513—5:; 2 



from shoal nets (228 fish) and from bull nets 

 (202 fish). The data on age were used to compare 

 the age composition of the catch in gill nets %vith 

 that of impounding nets. 



All specimens for which length and weight were 

 recorded (23,158 fish) in 1927-37 were used in the 

 study of the length-weight relation. The length- 

 frequency data for the years 1927-37 were based 

 on 58,665 specimens taken from random samples 

 only and included those specimens whose ages 

 were determined, most of those used in the study 

 of the length-weight relation, and a large number 

 for which lengths only were obtained. The length 

 distribution of 1,114 yellow perch taken in 1943-48 

 by trap nets was used for comparison with the 

 earlier material. 



Investigation of the relation between scale length 

 and body length was based on the examination of 

 selected or "key" scales from 600 specimens col- 

 lected in western Lake Erie as follows: September 

 to November 1928, 188; May to August, and 

 November 1929, 79; October 4, 1934, 207; April 

 1937, 60; and late autumn 1937, 66. The scale 

 measurements from only 576 of these specimens 

 could be used, since 24 individuals had lost the 

 designated scale or had key scales that were re- 

 generated, injured, or otherwise atypical. The 



