Fishery bulletin of the Fish and Wildlife Service - NOAA

30 FISHERY BULLETIN OF THE FISH AND WILDLIFE SERVICE
of measured length. This has been done on 2,500 fish, and the results are shown by
the solid line in figure 20. The average lengths of striped bass from 1 to 4 years old
have been calculated from the scales of 4-year-old bass of measured length (see below).
This is indicated in figure 20 by the dot-a,nd-dash line. There is every reason to
believe from the available samplings of fish of the ages covered by this part of the
graph that the lengths derived by this method are accurate estimates. Further
than this, it will be noticed that in the center part of the growth curve in figure 20,
where the lengths at different ages calculated by both the above-mentioned methods
overlap, there is an almost perfect correspondence in the estimated lengths as derived
by the two different procedures. It should be emphasized again, hi connection
INCHES S 10 £O 25 30 35
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9 DIFFERENT AGE GROUPS
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FROM MEASUREMENTS ON 2500 FISH
FIGURE 20.— The growth of the striped bass, as calculated from scales and the average lengths of different age groups. See Table
14 for average lengths of striped bass at the time they become 1 year old, 2 years old, etc., to 9 years old.
with figure 20, that the lengths represented on this graph are averages, and that
there is a wide variation about the mean in the lengths at any age. This is of
course particularly true among the larger sizes, as is indicated by the broken, line at
the upper end of the growth curve. In general, fish 100 cm. (nearly 40 inches)
long average about 25 pounds and are about 11 or 12 years old; those 125 cm., (nearly
50 inches) long weigh approximately 50 pounds and are roughly 20 to 25 years old.
The largest striped bass taken in recent years (caught hi Rhode Island on rod and
line in October 1936) weighed 65 pounds and measured 137 cm. (54 inches) ; examination
of several scales leads the author to believe that this fish was 29, 30, or 31 years
old. 10 • " ' : '
In calculating the growth of striped bass up to 4 years old by the scale method,
the following formula was used:
LI equals the length of the fish at the end of year "x," "V\ the length of the scale included
in the annulus of year "x," V the total length of the scale, L the length of the
fish from which the scale is taken, and С the length of the fish when scales first appear.
(The use of the factor С has various limitations, see pp. 31-32). The measurements
on striped bass scales were made from the focus to the anterior edge of the scale and to
the annuli along a line that bisected the angle formed by the junction of the two
ï« In connection with the age of striped bass, Bigelow and Welsh (1925) writ«, ". . . they are certainly long-lived, for onekept
In the New York Aquarium lived to an age of about twenty-three years."
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