MIGRATIONS OP COD 
95 
tagged cod (out of 1,600 marked) from these banks were recaptured along the coast 
of Cape Cod. 
If some of the cod from the north and east of Cape Cod which migrate to the 
wintering grounds between Rhode Island and North Carolina drop off, either on their 
way southward or on their return northward, to live on Nantucket Shoals, then the 
stock of fish in this latter region is kept up partly by grown fish from the Massachu- 
setts Bay region and from the offshore grounds between southern Nova Scotia and 
Georges Bank. Evidence of this is shown by the following data: Out of a total of 
only 196 cod tagged on Stellwagen Bank, in Massachusetts Bay, from 1923 to 1928, 
1 fish was recaptured between Rhode Island and New Jersey during the fall of each 
of the years 1923, 1924, 1925, and 1928 (no cod were tagged in Massachusetts Bay in 
1926 and only 10 in 1927), showing that there was a decided tendency for some of 
these fish to go southward each year. 
That some of the cod living offshore migrate to or beyond Nantucket Shoals is 
shown by the following recapture records: 1 of the 263 cod which we tagged off Cape 
Sable in 1928 was retaken off Chatham, Mass. On Browns Bank, 1,100 cod were 
tagged in 1927-28; and of the 28 recaptures reported up to the end of 1929, 2 fish 
had crossed the deep channel to the south and west, for 1 of them was taken 
on Georges Bank and the other in South Channel. On the northeastern part of 
Georges Bank, about 150 miles from Nantucket Shoals, 1,598 cod were tagged from 
1926 to 1928, of which only 12 were reported recaptured. But 3 of these, or one-fourth 
of the total, have been recorded from along the route to southern New England, as 
follows: 1 cod, tagged September 26, 1928, in about latitude 42° 00' N., longitude 66° 
22' W., was retaken on October 20 about 100 miles to the westward, toward Nan- 
tucket Shoals; while another fish tagged on the same date and in the same locality 
was recaptured on the shoals in May, 1929; of the cod tagged on Georges Bank in 
August, 1926, 1 was recaptured off Rhode Island in April, 1927. Some cod were 
tagged off southern Nova Scotia by the Biological Board of Canada. Among the 
recaptures are several fish taken on Georges Bank and several taken off Rhode Island. 
SUMMARY 
The size of the summer population of adult or nearly adult cod on Nantucket 
Shoals from 1923 to 1928 might be roughly estimated at between 3,000,000 and 
4,500,000 fish. 
Immigrant fish and the young which grow up in the Nantucket Shoals region 
have been sufficient to keep up the population there by offsetting losses due to deaths 
and emigrations. 
A large part of the cod fry which seek bottom on Nantucket Shoals appear to 
come from eggs deposited along the coast of Maine. But although fry may be 
plentiful on the shoals, it would seem that they contribute only in a small way in 
keeping up the local population, for relatively few 1 to 2 year old cod have been 
found there. 
Indications are that the stock of cod on Nantucket Shoals is kept up chiefly 
by the immigration of young adult and near-adult fish. Recaptures of tagged fish 
have indicated that the region to the northward of Cape Cod contributes annually 
but a small number of adult cod to the Nantucket Shoals grounds. The South 
Channel grounds and the southwest part of Georges Bank appear to be a more 
probable source, for, although scarcely any cod were tagged there and we have no 
105919—30 7 
