STUDIES ON THE STRIPED BASS OF THE ATLANTIC COAST 51 



lation summering in northern waters — that is, that they move up into Chesapeake 

 Bay in the spring as 2-year-olds (e. g., see under the last part of the section on migra- 

 tions) and then migrate to northern waters a year or more later. This is added 

 evidence that the dominant 1934 year-class, which first appeared as 2-year-olds in 

 northern waters in 1936, came from the general area of Chesapeake and perhaps 

 Delaware Bays, although evidence of the above type should be obtained for severa 

 successive years before it can be considered conclusive proof of the fact that the 

 contribution to northern waters in the spring and summer comes essentially from the 

 latitudes of Chesapeake and Delaware Bays each year. 



Measurements of the growth zones of scales from striped bass born in 1936 in 

 the Delaware Bay and Albemarle Sound regions are shown in figure 34. It will be 

 noted that the widths of the second growth zones of the scales from the fish of Dela- 

 ware Bay origin born in 1936 are slightly below those for the growth zones on the 

 scales from the fish of Chesapeake Bay origin born in 1935. (Compare upper set of 

 curves in fig. 34 with middle set of curves in fig. 33.) It is probable that this differ- 

 ence is at least in part due to the fact that the second growth zones on the scales from 

 the Delaware Bay fish were not yet quite complete (the fish were taken on November 

 8, 1937) because the annuli on scales do not appear until spring, although the growth 

 from November to March is almost negligible. Whether or not there is a constant 

 difference in the widths of the second growth zones of scales from fish of Delaware 



LENGTH FREQUENCIES OF GROWTH ZONES ON SCALES FROM 

 FROM YEARLING AND T WO" YE AR- OLD? STRIPED BASS IN 

 1937-1938 



OvlUBCft B. I9ST 



Figure 34.— The length-frequencies of the growth zones on scales from yearling and 2-year-old striped bass taken in Delaware Bay 

 and Albemarle Sound in 1937 and 1938. The measurements making up these curves have been smoothed by threes throughout. 



and Chesapeake Bay origin remains to be seen from sampling over a period of years. 

 It is probable that this method will not provide a good means of distinguishing 

 between bass born in these two regions, as the environmental differences are appar- 

 ently insufficient to cause any constant difference in growth rate during the second 

 year. 



The widths of the second growth zones of scales from fish born in 1936 in Albe- 

 marle Sound (see lower set of curves in fig. 34) are interesting because although they 

 are quite great, they are not so distinctively different from the others as those from 

 North Carolina collected in 1937 (see bottom set of curves, figs. 32 and 33). They 

 indicate, in other words, that although a wide second growth zone is apparently a 

 characteristic of North Carolina fish from the general region of Albemarle Sound, 

 this characteristic varies from year to year sufficiently so that it can only be used as 

 a means of distinguishing fish of North Carolina origin from fish of Chesapeake Bay 

 origin when the scales from fair samplings of bass that are just becoming 2 years old 

 in the spring, before any coastal migrations have been undertaken, are available 

 from both areas during any one year. 



In conclusion it should be emphasized once more that the available evidence 

 from general observation, scale analysis, and tagging experiments, gives every indi- 

 cation that the dominant 1934 j^ear-class originated chiefly in the latitude of Chesa- 

 peake and Delaware Bays; that those fish produced in North Carolina contribute 

 directly only a relatively small fraction to the population summering in northern 

 waters; and that the main body of the northern summer population of striped bass 

 comes from the area bounded on the south by Virginia and on the north by New 

 Jersey. Further proof that Chesapeake Bay in general contributes a large propor- 

 tion of the stock summering in northern waters is seen m figure 35, where the catches 



