48 



FISHERY BULLETIN OF THE FISH AND WILDLIFE SERVICE 



that the members of the dominant 1934 year-class that visited northern waters in 

 1937 were of much the same origin. It should be mentioned that measurements of 

 the first and second growth zones on the scales from 2-year-old bass in Connecticut 

 waters in 1936 (members of the 1934 dominant year-class) also gave length-frequency 

 curves that were exactly comparable to those shown in the top three sets of curves in 

 figure 32. Had they been of different origin — from areas scattered along the entire 

 length of the Atlantic coast — it would be expected that the distribution of the length- 

 frequencies of the widths of the first and second growth zones in these cases would 

 have been much wider and not nearly as constant in the range of measurement as 

 they actually are. 



1ST GROWTH ZONE 



CAPE COD BAY 



HARKNESS PT.CONN 



MONTAUK.L I . NY 



2ND GROWTH ZONE 3RD GROWTH ZONE 4TH GROWTH ZONE 



AUO 2-4,1937 



l 



SEPT 6, 1937 



OCT 26. 1937 



NCOWPtfTEWffSIWL ZONE 



CURRITUCK i MARCH 24.1937 



SOUND. H C I 



COMPLETE MARGINAL ZONE 



LENGTH FREQUENCIES OF GROWTH 

 ZONES ON SCALES FROM STRIPEO 

 BASS TAKEN IN DIFFERENT LOCAL- 

 ITIES IN 1937 



INCOMPLETE MARGINAL ZONE 



WIDTH OF GROWTH ZONES IN MMS 



Figure 32.— The length-frequencies of the growth zones on scales from striped bass taken in different localities in 1937. The meas- 

 urements making up each curve have been smoothed by a moving average of threes throughout. 



One other point is of interest in the length-frequencies of the growth zones on the 

 scales from these fish taken in northern waters in 1937. This is the comparison of the 

 fourth growth zones (incomplete marginal zones) of the samples from Cape Cod Bay 

 and Harkness Point. It has been pointed out in the section on age and rate of growth 

 that there is much evidence that striped bass north of Cape Cod grew much faster 

 than those south of Cape Cod during the. summer of 1937 (see fig. 19 and p. 29). 

 Since scale growth is proportional to body growth (see fig. 21), this phenomenon should 

 be reflected in the scales, and a glance at the length frequencies of the incomplete 

 marginal zones mentioned above (see fig. 32) shows this to be true. Thus the measure- 

 ments of the fourth growth zones of the scales from fish from Cape Cod Bay present a 

 peak slightly in advance of the similar peak for the Harkness Point sample, despite 

 the fact that the sample from Cape Cod Bay was taken more than 1 month earlier 

 than the one from Harkness Point. This is probably best explained by the faster 

 growth rate of the fish summering north of Cape Cod, for if the growth rates were 

 the same, the peak for the Harkness Point sample would have been far in advance of 

 the one for the Cape Cod sample, since it was taken so much later in the summer. 



