Subsequent grov/th can be traced by the monthly progression in the 

 position of that group from June, 1938, through Jfey, 1939, when the 

 dominant mode was near 120 ram. It is evident that the year class was 

 composed, at first, of several subgroups, the availability of vrhich 

 fluctuated more or less independently during the year. This accounts 

 for Irregularities in the progression. 



As for the ages of fish older than year class, it may be supposed 

 that in curves to the right of those belonging to year class 0, the small- 

 est fish, those around 8U to 100 mra. , in March, 1933, v/ere the smallest 

 one-year olds, and may be homologous with those ranging from 130 to 

 about 170 mm., in October, 1933, and to those of an undeterminable range 

 above 150 mm., in Ilay, 1939. From figure 3 it is sho^m that fish as 

 small as 1^0-l60 mm. were taken in the f5.ll comnercial fishery for "adults" 

 at Monterey in October, 1939- If this October, 1939, curve of figure 3 

 be comparable vrlth the October, 1938, curve of figure 1, it could be con- 

 cluded that at Monterey in 1939 some pilchards entered the fall commercial 

 fishery when in their second year. Nothing can be told by inspection 

 of frequency curves in figures 1 and 3 about, the, ages of the fish larger 

 than these sizes; they may be all one-year olds, or there may be an ad- 

 mixture of older fish. A knowledge of the age composition of these fish 

 is possible only by determining the ages of the individual specimens. 



The modes of curves in figure 1 do not coincide in position with 

 analogous modes indicated for 1921 and 1922 (fig. 2). These differences 

 may mean that the grovrbh rate of the comparable year classes was dif- 

 ferent, or that survival T^as different; or it may mean that selection 

 was different in 1938-39 than in 1921-22. In any event, it appears from 

 these differences that one cannot generalize, as to size and growth, from 

 one year class to another, or from the sampling of one year to that of 

 another. 



Young pilchards collected in Lower California in July and August, 

 1938, from ViTashington in April, September, and October, 1938, and from 

 Oregon in I;lay, 1939, do not correspond in size to those taken in California 

 during those months. This indicates that the California bait fishery 

 does not dravr from the entire juvenile pilchard population of the Pacific 

 coast. Lacking data for Lower California, ITashington, and Oregon in 

 other months, little can be judged from these data as to the age of fish 

 represented in the available frequency curves. Are the fish taken in 

 Lower California in July and August, 1938, fish in their first year, or 

 their second? The same question may be asked about fish taken in Vj'ashing- 

 ton in April, September, and October, I938, or at Coos Bay in Ilay, 1939. 

 These and other questions bearing on the age composition might be answered 

 by studjr of the scales and otoliths. 



37 



