MIGRATIONS OF COD 
103 
Increases in growth registered by recaptured tagged fish were very much the same 
in European waters as off our own coast. 
Gains in length shown by the cod tagged in Scottish waters by Fulton (1889- 
1892) amounted to about one-fourth to one-half inch in several months for fish rang- 
ing in length from 14 to 25 inches. The greatest increase was that made by a 15K-inch 
cod which measured 18 inches about seven months later (Fulton, 1893, p. 190). Ful- 
ton believed that the abrasion caused by the tag retarded natural growth. (Ibid., 
p. 177.) 
Schmidt (1907, p. 17) obtained only four dependable remeasurements from 
recaptured cod as a result of the tagging around Iceland in 1904 and 1905. These 
fish, about 20 to 24 inches long when tagged, increased about 2 ){ inches a year. Later 
tagging experiments done in Faxa Bay, on the southwest coast of Iceland, showed that 
8 of the cod (40 to 66 centimeters long when marked), recaptured 10 to 14 months later, 
had increased in length about 18 centimeters (7 inches) per year. This was a more 
rapid rate of growth than was found on the north and east coasts of Iceland, where 
the water is colder. (Saemundsson, 1913, p. 30.) 
Three cod (38 to 43 centimeters) tagged off the Faroes in August and recaptured 
in May, nine months later, had increased in length about 12 centimeters. (Winge, 
1915, p. 13.) In Danish waters some lots of tagged cod (35 to 57 centimeters) in- 
creased about 12 centimeters ( 4 % inches) during the first year after marking, while 
others (45 to 65 centimeters) increased only 7 to 9 centimeters. (Strubberg, 1922, 
p. 33.) 
According to these few records obtained from recaptured tagged cod, fish from 
about 14 to 25 inches long grew about 1% to 3 inches in length during one year off the 
east coast of Scotland, 3 to 4% inches in Danish waters, and as much as 6 to 7 inches 
off the Faroes and the southwest coast of Iceland. The latter appears to be much too 
high, especially when it was found that fry living around the Faroes and southern 
Iceland grew more slowly than those living in the North Sea (p. 99). The data on 
which these records are based are very meager, and, as Saemundsson (1913, p. 30) 
says, with respect to the Icelandic fish, they should be accepted with caution. If 
reliable remeasurements had been obtained from a large number of recaptured tagged 
fish instead of but few it is probable that cod ranging in length from 14 to 26 inches, 
living in the North Sea, would show an average increase of about 3 inches a year, 
with the smaller fish gaining somewhat more than the larger; in other words, very much 
the same rate of growth as was found for southern New England cod. 
EVIDENCE FROM SCALE STUDIES 
No attempt will be made here to give a detailed account of the studies that have 
been made on fish scales. This has been well covered by such authors as Thomson 
(1904), Dahl (1909), Taylor (1916), Lee (1920), Van Oosten (1929), and Graham 
(1929b). Growth of the cod’s scale has been described by Cunningham (1905) and 
Winge (1915) and scales in general by Paget (1920) and Creaser (1926). 
In this paper I have compared the growth and age of the cod according to its 
scales with that shown by length frequencies and the actual growth made by marked 
fish. Data are also presented concerning the zones of growth laid down on the scales, 
particularly the first growth zone and its significance in throwing light on the migra- 
tions of the cod. 
