264 



FISHERY BULLETIN OF THE FISH AND WILDLIFE SEEVICE 



16. The yellow perch of Lake Erie grew more 

 rapidly than did most of the perch of other waters 

 with which comparisons were made. 



17. Scales of Lake Erie yellow perch used by 

 Harkness (1922) were compared with those in the 

 present study, and the annual increments of 

 calculated length indicated no pronounced change 

 in the growth rate of 1927 from that of 1920. 



18. Length frequencies of the impounding-net 

 collections had a unimodal distribution each year, 

 but gill-net collections showed both unimodal and 

 bimodal distributions. 



19. The position of the mode in the length fre- 

 quencies fluctuated from year to year, and was 

 influenced to a considerable extent by the average 

 length of the dominant age group. The modal 

 frequency fluctuated over a wider range in the im- 

 pounding-net collections than in the gilled fish 

 from gill nets because of the greater selectivity 

 of the latter gear. 



20. The coefficient of condition K of individual 

 Lake Erie yellow perch ranged from 1.13 to 3.23, 

 and averaged 1.91. The state of the gonads 

 affected the coefficient of condition of the females 

 during the spawning season, at which time they 

 lost approximately 16 percent of their prespawning 

 weight. There are no data on the loss of weight of 

 males at spawning. At other periods condition 

 was not related to sex or state of maturity. 



2 1 . The coefficient of condition increased sharply 

 from June to July and remained at a high level in 

 August and September. In two of three years 

 condition declined in the autumn, but m the third 

 year it improved. 



22. Weight of the Lake Erie yellow perch in- 

 creased at a rate slightly greater than the cube of 

 the length. Over the interval of length to which 



the equation was fitted the empirical and calcu- 

 lated weights agreed closely. 



23. The year class of 1926 was unusually strong 

 and dominated the impounding-net catches of 

 1927, 1928, and 1929. There is evidence from the 

 samples of legal- sized yellow perch that the 1942 

 year class also was one of exceptional strength. 

 The year classes of 1936 and 1944 are believed to 

 have been of more than ordinary size. 



24. No relation between strength of year classes 

 and meteorologic conditions could be demon- 

 strated. 



25. The commercial catch (legal size) of both 

 impounding and gill nets was dominated by age 

 group III in the spring and early summer. Domi- 

 nance by group-II fish was characteristic of the 

 late-season catches of both types of gear, although 

 there are exceptions when age group III may be 

 dommant in both gears dui-ing the autumn. 



26. The sex ratio was determined to be 96 

 females to 100 males in the combined data from 

 all samples except those obtained in AprU, when 

 the ratio was obviously distorted. Evidence was 

 obtained of segregation according to sex in all 

 months from AprU to November, inclusive, except 

 September. It was pointed out that the number 

 of samples employed, as well as the number of 

 individuals examined, was important in the 

 accm'ate determination of the sex ratio. The 

 relative abundance of females in a year class 

 increased with age. 



27. Male yellow perch in Lake Erie matured at 

 an earlier age and at a smaller size than females. 

 Practically all males were mature or maturing at 

 a total length of 8 inches. Proportions of females 

 matm'e or maturing at different total lengths were 

 48.4 percent at 8 to Scinches, 86.1 percent at S>% 

 to 9 inches, and 97 percent at 9 to 9/2 inches. 



BIBLIOGRAPHY 



Alm, Gunnar. 



1917. Undersokningar rorande Hjalmarens naturfor- 

 hall§,nden och fiske. Medd. Kiingl. Lantbruksst., Nr. 

 204 (Nr. 3 kr 1917), 111 S., 5 pis. 



1918. Fiskeribiologiska stvidier fr&n sjon Lamen (Sm&- 

 land). Skrifter utgiviia av Sodra Sveriges Fisken- 

 forening, 1918, Nr. 3, S. 171-187. 



1919. Fiskeribiologiska undersokningar i sjoarna Toften, 

 Testen ocli Tien (Nerike). Medd. Kungl. Lant- 

 bruksst., Nr. 218 (Nr. 4 kr 1919), 50 S. 



1921. Undersokingar over tillvaxt och foda hos Klotent- 

 iarnarnas fiskarter. Medd. Kungl. Lantbruksst., Nr. 

 232 (Nr. 3 &r 1921), S. 121-144. 



1946. Reasons for the occurrence of stunted fish popu- 

 lations with special regard to the perch. Medd. 

 Kungl. Lantbruksst. Nr. 25, 146 pp. 

 BoLEN, Homer R. 



1924. The relation of size to age in some common fresh- 

 water fishes. Proc. Indiana Acad. Sci., vol. 33 (1923), 

 pp. 307-309. 

 Brofeldt, Pekka. 



1915. Om fiskarna och fiskeriforhailandena i Thusby 

 trask samt anvisningar till dessas forbattrande. 

 Finlands Fiskerier, Bd. Ill (1914-15), S. 106-123. 

 1917. Bidrag till kannedomen oni fiskbestindet i vS,ra 



