248 



FISHERY BULLETIN OF THE FISH AND WILDLIFE SERVICE 



Table 27. — Distribution by age groups of legal-sized yellow 

 perch from gill nets, 1927-28 and 1943-48 



1 Unweighted mean. 



' Minimum legal size wis 9 inches in 1927 and 1928 and 8!-i inches in all 

 later years. 



yellow perch in impounding-net and gill-net col 

 lections. The small numbers of specimens do not 

 warrant detailed comparisons of the remaining 

 age groups. Attention should be called to the 

 fact that in both 1927 and 1928 the samples taken 

 by gill nets did not contain fish caught as late in 

 the season as did those taken by impounding nets. 

 Consequently, the yellow perch taken by gUl nets 

 may be expected to have completed less of the 

 season's growth. Had the collections from both 

 types of gear been made at the same time within 

 the season, the advantage of the gill-net samples 

 with respect to the percentage of legal-sized yellow 

 perch in the age groups would probably have been 

 even greater. 



Differences in the age composition of collections 

 from the two types of giU nets were not great, 

 although there was a slight tendency for bull nets 

 to take more of the younger fish (table 25) . The 



only dominant group II occurred in the 1928 bull- 

 net collection, and when the data for 1927 and 1928 

 are combined, bull nets may be seen to have taken 

 relatively more fish of age group II than did shoal 

 nets and relatively fewer of the older age groups. 

 Likewise, the differences in the proportion of legal- 

 sized yellow perch in corresponding age groups of 

 shoal-net and bull-net collections were not large. 

 The best represented age groups (II and III) of 

 the shoal-net samples contained shghtly higher 

 percentages of legal-sized fish than the same age 

 groups in buU-net samples. 



The data on numerical and percentage age 

 composition of the legal-sized yellow perch taken 

 by gill nets are presented in table 27 with the 

 catches of shoal and bull nets combined. Added 

 to the 1927 and 1928 data are those obtained from 

 samples of the commercial catch by gill nets in 

 1943-48. Age group III dominated the samples 

 in both 1927 and 1928 and made up 58 percent of 

 the total at the then-effective size limit of 9 inches 

 (53 percent at the present 8K-inch size limit). 

 Age groups II and JV made up 26.1 and 14.1 per- 

 cent (33.6 and 11.8 percent at the 8K-inch limit) 

 and formed the only other well-represented groups 

 in the catches. Age group I was not represented 

 at all. The 1943-48 data differed from those of 

 the earlier years in that age-group-II fish domi- 

 nated in 4 years, age groups II and III were equally 

 represented in one, and age group III was domi- 

 nant in only 1 year. The averages for the 6 years 

 (comparable to the averages at the 8j2-uich size 

 limit m 1927-28) showed that group II made up 

 54.5 percent of the total, group III 36.5 percent, 

 group IV 7 percent, and group 11.6 percent. Thus 

 it is seen that there was not only a shift in domi- 

 nance from group III m 1927-28 to group 11 in 

 1943^8 but also an accompanying decrease in the 

 relative abundance of the fish in groups IV and V 

 and an increase in the number of those in group I. 



Explanation of the difference in age composi- 

 tion of the legal-sized yellow perch taken by gill 

 nets in 1927-28 and 1943-48 probably hes in the 

 time of year the fish were captured. All of the 

 1927-28 samples were collected in July and Au- 

 gust whUe those for 1943-48 were taken from late 

 September to early November. The samples ob- 

 tained in July and August (1927-28) unquestion- 

 ably were made up of fish that had not completed 

 the season's growth, whereas those taken later in 

 the year (1943-48) could be expected to have 



