Fishery bulletin of the Fish and Wildlife Service - NOAA

32 FISHEKY 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 С 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 С 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 ;
AND AVERAGE LENGTHS OF 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 summet 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 С is negligible, and does not affect
the points on the growth curve in figure 20 to a significant extent. It should be mentioned
that the use of a constant, G, although superficially plausible, is not sound
theoretically. The scale probably does not begin as a geometric point, but as a plate
whose radius may well approximate the size appropriate for the fish at that time.
GROWTH OF TAGGED STRIPED BASS AS SHOWN B v
MEASUREMENTS AT TIME OF RELEASE AND SUB-
SEQUENT RECAPTURE
LiTHlV l «u. Itt.l I «ч I .a. I.« | it. I II«. Ut I I .'• ^»'r U.tl
1936 1937 ï Э i B
.—The growth of tagged striped bass as shown by measurements at the time ol release and subsequent recapture.
Thus, in the weakfish (Cynoscion regalis) a negative О 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the negative Lee's phenomenon observed (Nesbit, unpublished material).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 increment
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.