STUDIES ON THE STRIPED BASS OF THE ATLANTIC COAST 



29 



ments of fish from any one region at any one time, and that the samples from different 

 areas may have been composed of stocks from widely separated localities which showed 

 different growth rates. Nevertheless, scale analysis (see Origin of the dominant 1934 

 year-class, pp. 46-52) points to the fact that the striped bass on which studies were 

 made in northern waters in the summer of 1936 and 1937, were mainly of essentially 

 the same origin and with similar growth rates in their first and second years. Figure 19 

 shows length-frequency curves for 2- and 3-year-old striped bass taken north and 

 south of Cape Cod in 1937. Those taken north of Cape Cod were from Massa- 

 chusetts, and those south of Cape Cod from Connecticut. The striking difference 

 in the striped bass of the same ages from these two areas is at once apparent. The 

 2-year-olds north of Cape Cod show a peak at approximately 40 cm., while those 

 south of Cape Cod have a peak near 34 cm. The 3-year-olds from the same areas 

 present peaks at 45 and 40 cm., respectively. It is almost certain that all these fish 

 were of southern origin (see Origin of the dominant 1934 year-class, p. 51), and that 

 they first migrated to northern waters as 2-year-olds in the spring (see Migrations, 

 p. 44). It is possible that the difference in size can be accounted for by differential 



LENGTH FREQUENCY CURVES OF TWO- AND 

 THREE- YEAR-OLD STRIPED BASS TAKEN 

 NORTH AND SOUTH OF CAPE COD, JUNE- 

 SEPTEMBER, 1937 _ 2YE4RSOL0 



3 TEURS OLO 



Fiqcke 19.— Length-frequency curves of 2- and 3-year -old striped bass taken north and south of Cape Cod from June through 

 September 1937. Data smoothed by a moving average of threes throughout (see Table 13 for original measurements). 



migration — that is, that the larger fish of the age-categories concerned migrated far- 

 ther north than the smaller individuals. This is unlikely, however, and the difference 

 in size is probably best explained by differential growth rates in the spring, summer, 

 and early fall in the areas under consideration. The samples from these areas are 

 perhaps poor, in that they are composed of rod-and-line caught fish in order that they 

 might be comparable, for it was impossible to get samplings of the population north 

 of Cape Cod over this entire period by any other method. The differences in size 

 may be slightly exaggerated, owing to the fact that the sampling in the early summer 

 south of Capo Cod was somewhat more intensive than that of the middle and late 

 summer, while the sampling north of Cape Cod was evenly distributed throughout 

 the entire period from June through September 1937. There can be little doubt, 

 however, that in 1937 the 2- and 3-year-old striped bass north of Cape Cod grew much 

 faster than those in Connecticut waters from June through September. 



The average length attained by striped bass each year from the first to the 

 tenth year has been calculated by two different methods, and is shown in figure 20. 

 It is of some interest that these lengths of striped bass at different ages compare 

 almost exactly with those given by Scofield (1931) and Clark (1938) for striped bass 

 on the Pacific coast. Since bass 2 years old and older were available in Connecticut 

 waters in large numbers, it was possible to calculate the average lengths of the differ- 

 ent age groups simply by making age determinations from the scale samples of fish 



