MIGRATIONS OP COD 
63 
At Round Shoal buoy a relatively small sample of cod was obtained (275 fish), 
but it was sufficient to show that the same stock of cod present throughout the spring 
and summer was still there. (Fig. 20, No. 3.) Although October begins the western 
migration of cod from Nantucket Shoals and from grounds to the north and east, 
the lengths of the Round Shoal October cod do not suggest that there had been even a 
small influx of foreign cod. We did, however, find cod somewhat less plentiful on the 
Round Shoal grounds in the fall than during the spring and summer of 1927, so that a 
small part of the stock of fish could have already started westward without such a 
fact being registered in the graph. Again, the dominant length of the D cod remained 
at 21 inches, as it did during the period from June to late August, and it would 
appear from this that these cod grew but little throughout the summer. 
At Great Rip we had a somewhat different situation in October, 1927. (Fig. 22, 
No. 3.) The D cod were still dominant at 23 to 25 inches, compared to 22 to 24 
inches in June, 1927, but a new school with individuals greater than 26 inches long 
arrived on the grounds some time between the middle of June and October. Appar- 
ently this school was not very large, for it was not found between Round Shoal and 
Rose and Crown buoys. (Fig. 20, No. 3) It is likely that these larger fish were on 
their way westward and that they originated from a region other than Nantucket 
Shoals or, at any rate, from a part of the shoals where no tagging had been done. 
Summing up the year 1927, we find that the same school of cod was distributed 
over all the tagging grounds throughout the spring, summer, and fall. These fish, 
designated as the D cod, were first noted on Nantucket Shoals in August, 1925 
(fig. 17, No. 3), when they were around 14 inches long and formed only a relative^ 
small part of the total stock of cod. In October, 1925, the D cod were just a little 
more prominent than in August. (Fig. 17, No. 4.) They were next found on the one 
cruise made in 1926 in September at both Great Rip and Round Shoal, where they 
formed the dominant school. At Great Rip in 1926 the individuals of the D school 
centered around 20 inches long and at Round Shoal around 18 inches. Throughout 
1927 this D school was even more dominant than in 1926 and monopolized all the 
tagging grounds at all times, excepting at Great Rip, where a small school of large 
fish appeared in the fall. 
A smaller percentage of Nantucket cod was recaptured to the westward during 
the winter of 1926-27 than during any of the other winters since 1923, so it is apparent 
that a large part of the D cod remained stationary on Nantucket Shoals throughout 
1926 and 1927, neither emigrating during those summers nor migrating westward 
during the winter. As the C cod disappeared from the shoals during the winter 
of 1926-27 most of them probably migrated westward the fall of 1926, but a large part 
of the catch made in the Rhode Island-North Carolina region that winter evidently 
consisted of fish which migrated from parts of Nantucket Shoals, where no tagging 
had been done, as well as from the regions to the north and east of Nantucket. If 
many of the cod came from the latter locality they did not pass over the Nantucket 
tagging grounds when we were fishing there in October, 1926, nor were they present 
on the shoals during 1927, or they would have been detected then in the length 
frequencies of the fish caught. Such of these fish as survived the winter in the Rhode 
Island-North Carolina region returned eastward in the spring and evidently did not 
stop on Nantucket Shoals. 
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