102 
BULLETIN OF THE BUREAU OF FISHERIES 
bined in the table which follows. About one half of these remeasurements were made 
on Nantucket Shoals by the tagging vessels, while the half which came from fishermen 
were from fish nearly all of which were recaptured between Rhode Island and Delaware. 
Table 38. — Increase in growth registered by Nantucket Shoals cod between the time of tagging and 
recapture 
- 
Lengths of fish in inches at time of tagging 
Number 
of fish 
Average 
time in 
months 
from date 
of tagging 
that fish 
were re- 
captured 
Average 
increase 
per month 
in inches 
17 to 20 
28 
8.4 
0.32 
21 to 24 
58 
5.3 
.33 
25 to 28 
54 
5.8 
.21 
29 to 32 
35 
6.7 
.22 
33 to 35 
6 
7.7 
.19 
The average time of recapture from the date of tagging, given in Table 38, in- 
cludes many records of fish caught after they had been at liberty only one to three 
months, but these are balanced by other recaptures made as much as 20 to 24 months 
later. The average increase per month was obtained from each individual recapture 
record. Thus, a fish recaptured after two months showing a gain in length of 0.50 
inch would be classed at a rate of 0.25 inch per month, as would also a fish taken 12 
months later showing an increase of 3 inches. 
We are justified in using the increase in length per month to calculate the increase 
per year because cod recaptured after they had been at liberty for more than one year 
had not grown at a rate appreciably different from those which had been at lib- 
erty only a few months. Data on the 12 to 24 month fish are as follows: Fish 17 to 
20 inches long at the time of tagging grew 0.29 inch per month (8 fish); 21 to 24 
inch fish, 0.30 inch (10 fish); 25 to 28 inch fish, 0.22 inch (9 fish); 29 to 32 inch fish, 
0.25 inch (8 fish); and the 33 to 35 inch fish, 0.19 inch (2 fish). 
A m ong the individual records of fish taken long after tagging are the following: 
A 28-inch cod gained 5 inches in 18 months; a 26%-inch cod gained 5.25 inches; a 
16%-inch fish gained 6.25 inches in 20 months; a 16%-inch cod gained 11% inches in 
24 months; and a 23%-inch cod gained 3 inches in 37 months. This latter fish was in 
poor condition and its growth was considerably below normal. It was not included 
in Table 38. 
An attempt was made to detect a difference in growth between winter and summer 
by segregating the recaptured and remeasured cod into two groups. But as none of 
the fish fell wholly within the winter season, no marked difference in the rate of growth 
was noted between those fish tagged in the fall (September-October) and recaptured 
in the spring (April-May) and those tagged in the spring and recaptured in the fall, 
possibly because in each instance there was a fast and a slow growing period which 
balanced each other. A seasonal difference in the rate of growth was more evident 
from our length-frequency data. 
According to the growth registered by tagged fish, Nantucket cod 17 to 24 inches 
long increase in length about 4 inches a year, while fish 25 to 35 inches long increase 
about 2% inches a year. These size segregations were made arbitrarily, for it is ob- 
vious that there is not a sharp demarcation between the two groups, and as the fish 
become older there is a gradual decrease in the gain in length that occurs each year. 
