— 206 — 
I have previously (p. 199) given a table showing the variations in the quantity of fish 
taken at Lofoten during the month of April, the latest month in which the fishery ever 
oceurs. And it is a very curious coimeidence, if such it be, that in the two years 1903 
and 1904, when the rich year classes previously referred to were spawned, the fishery 
set in remarkably late, in comparison with previous and subsequent years. In 1903, 
68.6 % of the total Lofoten yield for the year was taken in April; in 1904, the per- 
centage for April was 78.1, whereas the usual figure is a little over 20 %. In considera- 
tion of the foregoing, it might well seem possible that the high numerical value of these 
two year classes, especially that of 1904, should be due to the fact that the spawning 
set in so late as to ensure an adequate supply of nourishment for the young laryee at the 
stage when this was required. This question appeared to me of so vital importance, 
that I thought it best to lay the facts before one of the greatest authorities on micro- 
scopic plant life, H. H. Gran, who entirely agreed with me as to the significance of 
the point at issue. We therefore, in September 1913, laid before the International Council 
for the Investigation of the Sea a proposal concerning the organisation of future research 
work, both as regards the question of nourishment in young stages of fish, and the spring 
flowering of microscopical plants. The International Council subsequently agreed to 
devote especial attention to these questions during the coming years*), 
Drift of the larvæ and young fry with the currents. 
I have already drawn attention to another point which might be considered as pos- 
sibly exerting some influence upon the mortality of fish in the early stages, viz, the 
passive movement of the larvee with the currents. During the first cruise of the “Michael 
Sars” in the Norwegian Sea, I encountered great numbers of young cod fry drifting in 
the water above the great main depression in this region. It is possible that many indi- 
viduals perish during such drifting movements: nothing is, however, definitely known 
as to this. It would be especially desirable to ascertain the extent of such movement, 
and how far the young fry are able to return, of their own volition, to such localities 
as offer favourable conditions for their further growth. 
Later stages. 
The remarks here set forth as to the conditions in respect of nourishment, and move- 
ments of the fish in their youngest stages, naturally also apply, in a certain degree, to 
the older individuals, the fish at every stage of life being dependent upon some or another 
form of nourishment, the available quantity of which is a factor of great importance. 
We have seen in the foregoing that the stock of fish yaries greatly in numbers from year 
to year; in like manner, recent investigations have shown that also other forms of animal 
life exhibit great variations in the numerical value of their occurrence. As regards the 
larger pelagic organisms, (larger crustaceans, cuttle fish, etc.), the uncertainty of quan- 
titative determination renders this difficult to prove; with regard to bottom organisms, 
however, the interesting investigations carried out of late years by C. G. Jon. PETERSEN 
have definitely proved the existence of great variations in the numerical value of the 
different year classes. No complete statement as to this work has yet been published; 
I had, however the privilege of learning from Dr. Jon. PETERSEN, in conversation, 
*) Rapports ét Proc. Verb. Vol. XIX Copenhagen, 1913, pp. 124—127. 
