Translation Series No.1211

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5 .. Age and growth of the salmon in
the main basin of the Baltic' Sea
For the determination of the individual growth of fish it is
necessary to obtain the increase in length or in weight during a known
period of time. That is possible in general only with the aid of tagging
certain individuals. When it is . desired to ascertain the increase for a
group of fish, then determinations of length, weight, and age are re-
quired. On account of this close connection, age.and growth will be treated
together in this chapter.
5.1. On the terminology of age and growth analysesl °
The numerous developmental stages of the salmon have had of old .
definite names, especially in the English language. A small fish, freshly
hatched from the egg is called "alevin" (yolk-sack brood)'. After the Yolk
sack has been absorbed and after theflah begins.to feed, it.is.called
"fry" (brood able to feed). During the following period of life, salmon
have the outward appearance of trout and are designated parr until the
transformation into smolt. Since the parr stage extends over several years,
the additional terma "fingerling", "summerling", or one-yeax x-year parr:
were introduced, according to the size and aee of the fish.
In the post-smolt stage (for development of smolt. see 4.1.1.)
the young salmon in the first year'in the sea ("speitzgen") are called
"mielnica". Grilse (Jacob!s salmon) are those fish that spawn already
after only two summers in the sea. Mentioned must be further the names
"kelt" (a salmon thai has spawned, but preserved its nuptial colours)
10 The essential deSignations have been taken from the paper by T. H.
Aria and . W.-J. M. Menzies "The interpretat ion of the zones on scales
of salMon...." (Rapp.Yroc., Vol. XCVII, 1936).
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