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Renewal of the stock affected by the fishery? 
In order to appreciate the influence of the fishery on the whole stock, we must first 
of all ascertain its effect upon the renewal of the same; i.e. the extent of the natural 
increase of the stock and the influence of the fishery upon the mortality. 
As regards the renewal of the stock, we have seen in the foregoing that this takes 
place, as in the case of the herring, in a very irregular manner, the number of young 
individuals which form the annual increment varying greatly from year to year. 
The renewal of the stock can thus scarcely be dependent upon so regular and con- 
stant a factor as the fishery; it must depend upon highly variable natural conditions. 
The mortality, on the other hand, would appear, from the facts already noted, to 
be greatly influenced by the fishery. The question is, whether this influence is so great 
as to prejudice the actual yield of the fishery itself, and how great is the mortality 
attributable to the fishery in comparison with that due to natural causes. 
The growth continues throughout a long period in the life of the cod, beyond the 
average age of the skrei. Thus we may find good growth in the case of 13, 14 and 15 
year old fish. It is obvious, that the earlier a fish is taken from the sea, the greater is 
the amount of possible future growth lost. How far it might be advisable to take the 
young fish, disregarding the far greater profit which it would represent if allowed to spend 
some years more in the sea, is a point which depends on many different factors, as for 
instance the chance of its death from natural causes unaided by man, and, of course, 
the chances of capturing it again. The greater our knowledge as to the longevity of 
the stock and the percentage taken by the fishery, the better shall we be able to deal 
with this important question. Continued observation will also furnish reliable informa- 
tion as to the serious problem of how far the longevity of the skrei is gradually being 
reduced; whether the fish, owing to the increased intensity of the fishery, exhibit a con- 
stantly diminishing average size. As to past years, there is but little material available 
in this respect: we have only the frequently mentioned average weights from Lofoten. 
These show, for the period from 1861—1869, an average weight (gutted) of 2.54, for 
1882—1891 of 2.8, and for 1900—1909 of 2.42. It would seem impossible to draw any 
other conclusion from these figures than that the average weight of the skrei is subject 
to contmual variation. 
Relation between the periodical variations in the average size of the skrei 
and the fluctuations of the fishery. 
We have now seen, that during the period when the 1904 year class played a great 
part among the Finmark stock and the skrei, there was a close connection between 
the occurrence of this year class and the yield of the fishery in subsequent years. We 
have also learned that the 1904 year class is not the only one which has been distinguished 
by a higher numerical value than usual, but that it appears to be a regular feature in 
the history of the skrei stock, that rich year classes arise at somewhat varying intervals. 
In Fig. 100 I have marked off, uppermost (A) the yield of the herring fisheries, the 
spring herring, (fully drawn) and fat herring, (dotted line); below, the cod fisheries, Curve 1 
the skrei and Curve 3 the Finmark fish, while Curve 2 shows the fluctuations in the 
weight of liver, which exibit a movement corresponding to that of the average weight 
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