MIGBATIONS OF COD 
29 
stock of cod to the wintering grounds than did the eastern part, if tagged fish may be 
taken as a criterion. Thus, from the Round Shoal, Rose and Crown, Pollock Rip 
and Bass Rip grounds (northern part of Nantucket Shoals on its western side), where 
16,544 cod were tagged, 199 fish, or 1.2 per cent, were recaptured to the westward the 
first fall to spring following marking; from the Great Rip grounds (southern part of 
Nantucket Shoals on its western side), where 3,350 cod were tagged, 31 fish, or 0.93 
per cent, were recaptured; while from Davis Bank and the grounds 5 to 12 miles 
east-southeast of Round Shoal buoy (toward the eastern edge of the shoals) only 12 
fish, or 0.51 per cent, out of 2,331, were recaptured. 
Further proof that the cod which summer off southern Massachusetts make up 
a large part of the winter population to the westward has been furnished by an analysis 
of the length-frequency distributions of the fish caught in these regions. 
The size distribution of all the cod caught by the Halcyon and the Albatross II 
on Nantucket Shoals is shown in Figures 15 to 24. It can be seen that relatively few 
fish less than 23 inches long were taken on the shoals in 1923 or 1924. In line with 
this, very few cod less than 23 inches long were reported caught to the westward of the 
shoals during the winters of 1923-24 and 1924-25. The data for 1925 revealed no 
outstanding size group off southern Massachusetts nor to the westward. In 1926 
Figure 8— Length-frequency distribution of 1,291 cod caught on Nantucket Shoals October 14-17 (solid line), and 185 
taken on the Cholera Bank, November 14-21, 1927 (broken line) 
small cod, particularly 17 to 20 inch fish, predominated on those parts of the shoals 
where tagging was done (fig. 19), and during the winter of 1926-27 cod 16 to 22 inches 
long were taken between Rhode Island and Delaware in far greater numbers than for 
many years past; in fact, they were the dominating size groups there that winter. 
The same was true of 1927, when 20 to 24 inch cod predominated on the shoals and 
likewise to the westward. 
The fall of 1927 it was possible to make a direct comparison between the lengths 
of the cod on the Cholera Bank in November and those of the fish present in Nantucket 
Shoals the preceding month. These are shown in Figure 8. It can be seen that the 
fish centering around 23 inches formed the dominant size group both on the shoals 
and on the Cholera Bank. The 29-inch Nantucket fish were evidently not present 
on the Cholera Bank at the time we fished there. These larger fish were caught 
chiefly at Great Rip buoy, and it is interesting to note that according to the recapture 
dates of these Great Rip 1927 fish (Table 17) they migrated westward from Nantucket 
Shoals later in the season than did those from the Round Shoal grounds, which might 
account for their absence in our Cholera Bank catches. 
