STUDIES ON THE STRIPED BASS OF THE ATLANTIC COAST 25 



character of the circuli that border it. This type occurs most commonly on scales that 

 overlap a regenerated scale. It appears that the process of regeneration in a scale 

 modifies the growth of adjacent scales sufficiently to form false annuli on the latter. 

 This type was observed frequently, particularly on scale samples from tagged fish 

 that had been recaptured and had regenerated scales in the area from which a sample 

 was taken at the time of their original release. Regenerated scales were common 

 in all samples, often forming at least 10 percent of those examined. _ Sometimes 

 entire samples had to be discarded because there were no scales that were not regen- 

 erated. Up to 15 percent of the samples have been rejected on rare occasions 

 because of false annuli, regenerated scales, and other factors which made the age 

 determinations and scale measurements subject to serious errors. Scales from larger 

 striped bass were found to be much more difficult to read for age than those from 

 smaller individuals. Not only did the first annuli become indistinct, but there were 

 likely to be more false annuli so that age determinations were confusing. For this 

 reason growth calculations by the scale-measurement method have been confined to 

 fish less than 5 years old. Particularly on scales from fish over 8 years old it was almost 

 impossible to be sure that the age reading was correct, and on fish of this size or larger 

 it was only feasible to make approximations as to the age of each individual. As a 

 check on age determinations of striped bass of all sizes the growth rings on otoliths 

 have frequently been counted, and it was foimd that on individuals up to 3 years old 

 this method was satisfactory. The opercular and subopercular bones have also been 

 examined for annular markings, which were best seen after these bones had been 

 cleared in a half-and-half mixture of 5 percent glycerine and potassium hydroxide. 

 On the whole such markings were found to be indistinct and irregular, and did not 

 constitute an adequate means of making age determinations. 



Since the youngest striped bass taken in Connecticut waters during the course 

 of the investigation were 2 years old, age determinations and rate of growth studies 

 on juvenile and yearling fish were necessarily confined to material from elsewhere. 

 The growth of the larvae has already been discussed under spawning habits and early 

 life history (p. 19). The smallest juveniles that have been taken in their natural 

 habitat have also been described, and, as is shown in figure 14, these fish, which 

 were not more than 1 month old at the time they were seined in Albemarle Sound, 

 averaged about 2.7 cm. in length. Figures 10 and 11 show the range in size of 

 juvenile bass from the Hudson River, and of juvenile and yearling bass from Dela- 

 ware Bay. It is apparent that juvenile striped bass in the Hudson averaged 5-7 cm. 

 in length by the middle of the summer (see fig. 10). The juvenile bass taken in 

 Delaware Bay in November 1937 formed only a small part of the curve shown in 

 figure 11, the bulk of this sample being made up of yearling fish. The juveniles at 

 this time, however, were from 9.5-12.5 cm. long. Growth practically ceases in the 

 winter, and when striped bass become 1 year old in the spring they average 11-12 

 cm. long. Six yearling individuals taken in the Hudson River in July and August, 

 1936 and 1937, averaged 14.3 cm. (extremes 12.0-15.9 cm.). The yearlings in the 

 Delaware Bay region (see fig. 11) averaged approximately 19 cm. in November 1937. 

 By the time they become 2 years old striped bass are about 20-23 cm. in length, and 

 it is at this age that this species probably first takes any large part in the coastal 

 migrations. It should be mentioned at this tune, however, that even in juvenile 

 and yearling striped bass there is a tremendous variation about the mean in the meas- 

 urements of any age group at any one time, as can be seen from figure 1 1 . The subject 

 is further complicated since the populations under consideration were from different 

 areas where in all probability slightly different growth rates occur. Thus the lengths 

 given for striped bass of different ages throughout can only be rough approximations. 



Fish 2 years old and older were sufficiently abundant to give ample material for 

 growth-rate studies in Long Island and New England waters, particularly on the 

 members of the dominant 1934 year-class. Figure 17 shows length-frequency curves 

 of all striped bass measured in Connecticut waters from April through October 1936 

 and 1937. The prominent peaks that characterize these two curves are mainly made 

 up of the 2-year-olds in 1936 and the 2- and 3-year-olds in 1937, and they give some 

 idea of the relative abundance of the members of the 1934 year-class. The measure- 

 ments that make up these graphs come mainly from seined individuals, but they also 

 come from fish that were caught on rod and line and in pound-nets. Although this 



