32 j] 



FISHERY BULLETIN OF THE FISH AND WILDLIFE SERVICE 



obtained by means of the product moments method, and it was found that the line 

 intersected the abscissa at 0.6 cm. This value for the length at which scales first 

 appear seems to be too low in view of the evidence mentioned above, but it has been 

 used for the factor C in the scale formula for lack of any other means of determining 

 it more accurately. There is no evidence, as shown before, that scale growth and body 

 growth in the striped bass are proportional in individuals below 11 cm., and an error 

 in the value of 0.6 cm. for C may thus be introduced, since the method applied above 

 necessarily assumes such a relationship. It is considered likely that scales do not 

 first appear until the bass are about 1.0 cm. long, and that scale growth is not directly 



ANNUAL INCREMENT IN LENGTH OF STRIPED BASS 



~°— — _ 



CALCULATED FROM GR 

 ANO AVERAGE LENGTHS 



DATA FROM SCALE 

 AGE GROUPS 



Figure 22.— The annual increment in the length of the striped bass. The annual increments through the fourth year are calculated 

 from the scales from striped bass of the 1933 year-class caught in northern waters in the summer of 1937. The annual increments 

 in the fifth to eighth years inclusive are calculated from the average lengths of the age groups involved, these lengths being 

 taken from fish caught in northern waters in 1936 and 1937 (see Table 16 for actual figures on annual increment). 



proportional to body growth until a short time after they have formed. But the error 

 introduced in the calculation of the lengths of striped bass at different ages from the 

 scale formula by this discrepancy in the value for C is negligible, and does not affect 

 the points on the growth curve in figure 20 to a significant extent. It should be men- 

 tioned that the use of a constant, C, although superficially plausible, is not sound 

 theoretically. The scale probably does not begin as a geometric point, but as a plate 

 whose radius may weU approximate the size appropriate for the fish at that time. 



GROWTH OF TAGGED STRIPED 9ASS AS SHOWN 6 

 MEASUREMENTS AT TIME OF RELEASE AND SUB- 

 SEQUENT RECAPTURE 



f,... U, I ... I ,.., I „, I ... I ... | ... I ... I .i. I ... I ... I .... I ,„., I ... I „„ l «, I ... I ... I ,t. I ,„ I ... I ... I ... Uil 

 1936 1937 1938 



Fiouee 23. — The growth of tagged striped bass as shown by measurements at the time of release and subsequent recapture. 



Thus, in the weakfish (Cynoscion regalis) a negative C would be needed to correct for 

 the negative Lee's phenomenon observed (Nesbit, unpublished material). 



The annual increment in the length of the striped bass is shown in figure 22. It 

 is apparent that the greatest growth occurs in the third year, that age at which this 

 species first undertakes coastal migrations to any great extent. Thereafter the incre- 

 ment in growth falls off sharply, particularly in the fourth year, and from then on 

 maintains an average of about 6.5-8.0 cm. each year at least up to the eighth year. 

 There is some evidence from the available material that the growth rate decreases 

 still more in the eighth and succeeding years. 



The growth of tagged individuals that were measured at the times of release 

 and subsequent recapture provides a good means of checking on the calculated growth 

 rate of the striped bass as shown in figure 20. This material is shown in figure 23. 



