gation is, however, an extremely lengthy and difficult task; it is therefore of the greatest 
importance to ascertain whether it may not be possible, when once a comprehension 
of the races has been obtained, to discover some more easily discernible distinctive 
marks by which to determine to which race the single individuals belong, and 
properly sort the mixed samples. Such a system can, in many cases at least, be 
found in the study of the degree of maturity exhibited by the genital organs, and 
where this in itself is not sufficient, a combined observation of the size of the fish, 
its degree of maturity, type of growth, and age, will go far to attain the desired 
object. These investigations are essentially easier, and therefore permit of extensive 
examination of specimens and samples, which is naturally a necessity if one desires 
not only to solve the zoological problem of distinction between the different forms, but 
also to follow the natural geographical distribution of the same, with the natural history 
of the different races in certain areas of sea. Such investigations will, of course, in their 
results, arrive at the same object as the more anatomical racial study, showing, for in- 
stance, as we have seen in the previous chapter in the case of the Norwegian coast her- 
ring, the natural area of migration of a race. On the basis of such investigations, also, 
one arrives at the question of variation in the migrations and size of the stock, which 
is of especial importance in dealing with the problem of fluctuations in the fishery. 
The investigations which we shall here especially consider have been particularly 
directed towards this end. As will be seen from the following, greater difficulties 
have been encountered in the North Sea than in the Norwegian waters; the investiga- 
tions have not been carried on for so long a period of time, and can therefore not present 
so definite results. They serve however, at least to point the way for future investiga- 
tions of the same nature. I will now briefly state the most important results which have 
been obtained. 
Mixture of races in the northernmost part of the North Sea. 
At the conclusion of the last and commencement of the present century, some few 
Norwegian fishermen began to take part in the herring fishery on the North Sea Banks; 
they worked, however, grounds which are only rarely and to a slight extent fished by 
other nations, viz. along the so-called “Revkant”, or 100 fathom curve, which forms 
the boundary between the North Sea Banks and the Norwegian Channel. There is 
in particular one small bank near the Revkant, called the Viking Bank, due west of Ber- 
gen, and this bank formed the true fishing ground of the Norwegian fishermen. 
The catch which these fishermen brought to land exhibited great variation in “qua- 
lity”, being now fat, early “fulls”, now far advanced fulls, sometimes spent fish, and 
at other times a mixture of all sorts. Investigations in the Fishery Laboratory very soon 
convinced me that these hauls must consist partly of Shetland herring, partly of fish 
belonging to the Norwegian race, and I endeavoured to test this by means of fishing ex- 
periments carried out in the northern part of the North Sea, and by subjecting the fish 
to close study, both according to the method laid down by Hrıncke and also other and 
simpler methods, especially size and degree of maturity*). 
These experiments will be referred to again in a later chapter, as they contribute 
*) See Norske Havfiske, II Del, p. 310 ff. and Laurits Devold og Johan Hjort: Norsk Silde- 
fiske i Nordsjsen. Norsk Fiskeritidende. 1906. 
7# 
