a 
wegian waters. The scales thus serve as a kind of certificate of origin, legible even when 
the fish are encountered in waters far distant from those of the northern coasts of Nor- 
way. In other words, it is possible to study the migrations of these fish in the same 
manner as when dealing with specimens marked and set free for purposes of investiga- 
tion. Whereas the scientist, however, may mark his thousands of fish, and possibly 
recapture some few hundred, nature has here marked millions, and millions may be 
caught. During the ten years 1907—1911, the occurrence of these “marked” fish has 
been closely studied, and their mi- 
grations may be traced, more’ or less 
acurrately, as in Fig. 24. 
“Moving from the northern Nor- 
wegian waters, they have passed 
southward in great numbers, to find 
a spawning place off the west coast, 
encountermg here fish which had 
grown up in more southerly waters, 
and spreading, together with these, 
westward to the Faroes, and eastward 
to the Skagerak. Some few individuals 
have gone even farther, penetrating 
into the Kattegat, and the southern 
part of the North Sea, where they 
have been encountered in small num- 
bers among the herring having their 
habitat there. None of these fish are 
now to be found in the northern 
Norwegian waters, but farther south 
they still occur in numbers, and their 
appearance and migrations may be 
further studied”. 
It will be seen from the chart 
| (Fig. 24) that in 1908, the emigrant 
‘Fig. 24. Migrations of the »marked« herring. (LEA). Nordland herrmg began to make their 
appearance among the large herring 
off the coast of the Romsdal district, while in 1910, they were present in the spring 
herring shoals. This exactly corresponds to a great emigration of Nordland fat herring 
m 1909 and immigration among the spring herring in 1910, which, as we have seen in 
the foregoing, is strongly suggested by the composition in point of age of the two classes. 
Closer study of this phenomenon enables us moreover, to calculate the percentage 
furnished later on by the original Nordland fat herring contingent, when mature, 
among the shoals of large and spring fish*). 
In a sample of large herring, 47 % of the year class 1904 were found to be marked 
fish. As the earlier fat herring samples from Nordland revealed the fact that only 
2/, of the year class were marked, it is necessary to increase the percentage of 47 % 
*) Vide Hyorr and Lea. Publ. de Circ. No. 61. 
