14 
lively in the beginning of autumn, or already in the month of August, in 
the years when this fishery on the whole is carried on to any greater 
extent. This, indeed, has not heen the case of late years; some herrings, 
however, have come every year, and just at this time. I must suppose that 
these herrings come from the seas outside the Skaw, and do not stay with 
us continually. To be sure, I have formerly held another opinion on this 
question, because the herrings in the Belts are smaller than the herrings 
in the Cattegat; I thought this must necessarily indicate that we had to do 
with local races. This difference in size, which no doubt does exist, may 
be explained, however, in other ways also, which do not necessitate the 
theory of the herring”s great attachment to its native place. But I shall 
dwell no longer on this question”); I just wanted to point out the fact that 
an immigration of many various species of fish into our seas, is going on 
every autumn, an immigration which is evidently connected with the pouring 
into the Cattegat of certain masses of water (the "bank-water”). The same 
has been pointed out before already by Otto Pettersson with respect to 
Bohuslån, and by Møbius and Heincke with respect to the western part of 
the Baltic. 
This migration, which is repeated every year to a greater or smaller 
extent, but regularly at the same times, is known also from the western 
shores of Jutland. Here cod and haddock are absolutely missing in the 
summer, but in the winter, when the weather does not prevent it, they are 
eagerly fished for. Evidently, we have to do here with a very great and 
general migration of fish, encompassing the shores of North Europe, the 
closer study of which must be left for future, international investigations. 
When, according to the above, part of our cod immigrate as small, and 
grow up in our seas, while others, half-grown as well as large ones, immi- 
grate yearly, and none, or next to none, live through their whole life in our 
seas, then it is a logical consequence, that the cod in our seas, on the main, 
must be looked upon as a small part of the North Sea cod-tribe, which does 
not exist independently. They must be "children" of the North Sea cod and, 
") In Germany it is particularly Professor Heincke who has advocated this view, 
that the herring does not migrate far. But his proof of it — the occurrence of local 
races — is not satisfactory, a fact which has been pointed out also by Professor V. Hensen 
in "Wissenschaftliche Meeresuntersuchungen. Neue Folge. Bd. II. Heft 2. 1897. p. 76”. 
For the local races may very well be maintained and formed, even if the herring annu- 
ally migrates far, when it only returns again to its native place, says Hensen. He refers 
to the birds of passage, e. g. the stork, which every year undertakes long migrations, 
but which knows nevertheless to return to the same nest; for all that, we may very well 
speak of a special Scandinavian race of storks, and perhaps also point out anatomical 
peculiarities in it. The possibility that the fishes can possess a similar local sense, is 
not at all excluded; more particularly as it seems that we have found indications of it, 
e. g. by labelled salmon. These questions must be solved, as usual, with respect to the 
fishes, by direct investigations in the open nature, just as thev have been solved with 
respect to the stork. 
