Translation Series No.1211

Laie a large number of'grilse, which are practically not being taken in
the Baltic Sea.
G. Alm investigated the age composition of spawning swarms in
the rivers Torne, Kalix, Lule, Pite, Ume,. and M8rum. The number of the
in each sample, it is true, was only 21 to 337. The age
classes A.2 and older comprised 94 per cent of the total catches. Of these
36 per cent belonged into the age class A.2.
Thé series of meaelrements,from the Swedish rivers in the years
.1959/62 indicate that the share of the age class A.2+ in the spawning
stock is at present considerably greater than the percentage of salmon that
have spent more than three years in the Baltic Sea. In supplementing these
data we qan employ investigations about the share of salmon with spawning
marks in catches from the Baltic Sea. These fish are those that had already
spawned and had then ±eturned into the Baltic Sea. The energy required for
the journey and the act of spawning is supplied by the body reserves. This
includes a degradation of substance at the scale'margin. This absorption
zone is called the spawning mark. 8Cale samples for age determination had
been taken of à total of 6914 salimmthat had been caught in the sea. Among
these were 166 fish•(2.4 Per cent) that had already sPawned. If we neglect
the grilse and consider only the spawning times of 1957 to 1961 in which
all spawning age classes were fully included, it is found that 63 per cent
of the salmon with spawning marks had spawned in the third year of their
sojourn in the sea and 37 per cent had spawned later (Table 37). In the
preceding it has been attempted to employ the series of measurements in
the rivers, the share of salmon with spawning marks, the conditions of'
the salmôn and the maturing process of the ovaries as indicators for the •
age at the time of spawning. Here we see at ance two different results:
fish analysed