The next year class^ 19^2^ was a very strong one. This report does not 

 cover the fall of the year 195Uj when the 19^2 year class is expected to 

 reach the critical size i-ri-th respect to the selectivity of the li-l/2 inch 

 mesh, but in the second quarter of 195h<, large numbers escaped through the 

 meshes of the nets as vrill be shown. 



The effect of the mesh size in relation to year-class strength can 

 best be understood by a study of the size composition of the catches of the 

 large-mesh and small-mesh vessels. In figures 1 to 6 are presented the size 

 compositions of average catches for each 3-month period from January 1953 to 

 June 195U. The first two quarters C^igs. 1 and 2) are for the 6-month period 

 immediately preceding regulation and continue the reporting of size composi- 

 tions of catches presented in previous reports (Premetz 19^3, Premetz et al. 

 195U) . Vessels were not using large mesh during this oeriod.V The last 

 four graphs (figs. 3-6) are for the first year of regulation, beginning 

 July 1, 1953, during which both large-mesh and small-mesh vessels were 

 operating. 



To understand the length frequency curves it is necessary to rel'ate 

 them to year classes. In early 1953 the dominant year class was from the 

 1950 brood. This abundant group of 3-year-old fish was responsible for the 

 prominent mode in the length frequency curve for the first quarter of 1953 

 (fig. 1). This mode, then centered at about h3 cm., progressed with the 

 growth of the fish to about 52 cm. in the first quarter of 195U (fig. 5) . 

 During the second quarter of 195U this year class was taken in such rela- 

 tively small quantities that it cannot be identified on the length frequency 

 curve (fig. 6) . 



The following year class, that of 195l, was verj'- weak and nowhere pro- 

 duces a mode on the leng;;,h frequency curves. 



The group following this, the 1952 year class, was another strong one. 

 It is seen first on the length frequency curves in the second quarter of 

 1953 (fig 2) when large quantities were caught and discarded by the small- 

 mesh vessels before regulation. The average length at that time was about 

 27 cm. . The growth in size of this year class can be followed by the pro- 

 gression of the mode through the graphs to the second quarter of 195U when 

 the mode wa? centered at about hO cm. (fig. 6) . 



A very striking change in size composition occurred between the first 

 and second quarters of 195ij.. By the second quarter, most of the 1952 year 

 class had attained marketable size. This group of 2-year-old fish then 

 dominated the catches. The previous dominant year class, now h years old, 

 is hardlj-- discernible in the length frequency cuarve for this quarter 

 because of the extreme abundance of the 2-year-olds, The U-year-old group 

 of fish may not have been actually less abundant than in the previous quar- 

 ter but simply relatively less so. (Note that the vertical scale in figure 

 6 is not comparable to that in figure $) . 



1/ A few vessels converted promptly about June 1, 1953^, but data for these 

 vessels were not used for June in this report. 



