50 



FISHERY BULLETIN OF THE FISH AND WILDLIFE SERVICE 



the bottom of fig. 32 are also repeated for the sake of comparison at the bottom of 

 fig. 33.) These provide proof that the members of the 1935 year-class that contributed 

 to the population summering in northern waters as 2-year-olds in 1937 came, in the 

 main, from the Chesapeake Bay area. Thus the middle set of curves in figure 33 

 are measurements of the growth zones of scales from fish that were just becoming 

 2-year-olds in Chesapeake Bay in 1937. They are, in other words, from bass that 

 had not yet migrated to any great extent, and the curve for the second growth zone 

 may therefore be considered typical for bass that had been born inl935 in Chesapeake 

 Bay. The upper set of curves in figure 33 is from measurements of the growth zones 

 of scales from 2-year-old fish taken from northern waters in the summer of 1937. 

 They are from bass of unknown origin that had migrated north along the coast in the 

 spring. It will be noted immediately that the curve for the second growth zone of 

 the scales from northern fish in the summer of 1937 compares well with the similar 

 curve for the bass of the same year-class known to be of Chesapeake Bay origin. 



LENGTH FREQUENCIES OF GROWTH 20NES ON SCALES FROM 

 TWO-YEAR-OLO STRIPED BASS IN 1937 



£ - OCT, I95T 



ZONE 2-d G»0*TM IONE 



GROWTH ZONES 



Figure 33.— The length-frequencies of the growth zones on scales from 2-year-old striped bass taken in southern New England 

 southern Chesapeake Bay. and Currituck Sound (repeated from Figure 32 for comparative purposes), in 1937. The measure- 

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



However, it does not compare well with the similar curve for bass of the same year- 

 class known to be of North Carolina origin. (See lower set of curves, figs. 32 and 

 33.) There is somewhat of an overlap between the curves of the widths of the second 

 growth zones on scales from fish of the 1935 year-class of known origin from Chesa- 

 peake Bay and North Carolina, so that scales from fish of the same age-group but of 

 unknown origin that show a second growth zone measuring from about 2.0-3.0 mm. 

 might have been born in either of the above-mentioned areas. It is apparent that the 

 majority of the widths of the second growth zones on the scales from fish taken in 

 northern waters in the summer of 1937 fall below 2.0 mm. Judging from these 

 measurements, it is possible to say that the North Carolina fish (assuming the Cur- 

 rituck Sound sampling to be representative of that area) contributed at an absolute 

 maximum about 20 percent of the 2-year-olds summering in northern waters in 1937. 

 The percentage that North Carolina contributed to the northern population at this 

 time was probably much less. In fact, a comparison of the widths of the second 

 growth zones of the scales from fish of the same year-class from Chesapeake Bay and 

 from northern waters in 1937 (see fig. 33) shows that it is possible that North Carolina 

 did not contribute anything directly to the population of 2-year-olds summering in 

 the north in 1937, and that this population came entirely from the Chesapeake Bay 

 area or north of it. The latter, however, is undoubtedly an extreme view. 



It is thus apparent that in 1937 North Carolina contributed directly not more than 

 a small fraction of the 2-year-old striped bass summering in northern waters, and that 

 the 2-year-old bass in northern areas in that summer came mainly from the Chesa- 

 peake Bay latitudes and perhaps from the Delaware Bay region. There is, however, 

 a possibility that the fish born in North Carolina contribute indirectly to the popu- 



