Translation Series No.1211

treated as a quality, a special population i being treated as a quantity.
This development has been pushed ahead by strong economic interests. The
two spheres of problems can no longer be separated in the present-day stage
of salmon research. When we attemPt to comprehend the'emigration of the
young salmon into the sea quantitatively, then we establish chronological
changes. The causes for such changes cari, however, only be discovered, when
it is known which hormones effect a change that causes every fish to emig
rate and, among other things, makes it resistant to . the higher salt concen-
tration in the sea.
The present paper is intended to treat problems of the biology
and the study of the stock of the salmon in the Baltic Sea. In the sense
sketched above the biology stands.here for the quality and the stock for
the quantity. The goal of the investigations is to use the results reported
on for a quantitative understanding of the stock of salmon in the Baltic
Sea.
For this end it is necessaxy to treat first the fishing technique '
and the extent of the fishery. This chapter is intended to provide three
important results for later discussions. The first task is to obtain a
measure for, the intensity of the fishery and its changes. This is to make
it possible to ascertain the effects of the fishing on the stock. The second .
task is to ascertain yearly differences in the density of the stock. This
enables us to recognize natural effects on the population density. Finally,
we shall attempt to assemble the yields of the fishery that can be considered
as a product of the intensity of the fishing and of the - amount of stock.
. [P. 221]-,
Measures for the intensity of fishing and the ameunt of stock.
(ject, r)
can only be obtained when the equipment uàed and its manner of action are
known, and when furthermore the effects of external causes on the performarme.