Английский язык: Сборник текстов и упражнений. Дьякова Н.П. - 94 стр.

hatchery efficiency. Until now on Kamchatka we have estimated the return mostly
from the number and age structure of spawners near the hatchery itself. Neverthe-
less, hatchery fish stray to other areas, and wild fishes, in tern, can be observed in
the area of hatchery or wild fish straying. If we could asses this, the data would
be very helpful for estimating actual hatchery returns and interactions between
wild and hatchery fish. Therefore, there currently is a need for a reliable system, for
example like ones used in America to mark hatchery juvenile fish and to sample for
marks in the adult return. On Kamchatka we do not yet have such a system.
    A rather promising method is identification of fish using characteristics of
their scale structure, as well as structure of their eoliths or bones. Decoding this
information requires special equipment and experts that have special knowledge.
There are not enough such experts on Kamchatka yet, and equipment to do such
work is rather inadequate.
    To get reliable estimation of return rates, it is necessary to sample scales from
a majority of fish returning to each hatchery and to examine these samples for age
and origin. Identification of wild and hatchery fish requires creation and annual
updating of «wild» and «hatchery» standards. We began creation of these stan-
dards for wild chum and sockeye salmon from the Paratunka River system and for
Paratunsky Hatchery fish in 1996.
    We attempted to estimate rates of hatchery and of wild chum salmon in differ-
ent segments of Paratunka River in 1997. Discriminate analysis of complex scale
parameters , including 23–25 structural variables indicated, with high confidence
level (pO.OOOl), that approximately 50% of fishes entering the Paratunka River
were fish as were up to 90% of fish in Trezubets Creek near the Paratunsky Hat-
chery. Two conclusions could be suggested approximately half the total number
of spawners in Paratunka River in 1997, the second year of mass return, were hat-
chery fish and not less than 90% of the return to Paratunsky Hatchery consisted of
hatchery fish.
    We conclude that an insight to the functioning of hatcheries on Kamchatka
depends on further development of this work and applying it to other hatcheries.


          Smoltification of Hatchery Reared Young of Chum Salmon
                    in Two Various Regions of Kamchatka

    Differences have long been noted in the course of physiological processes
within individuals of a single Pacific salmon species, but from different parts of
its geographic range. However, specific data about salmon populations can
represent practical interest for predicting juvenile migration time to sea, evaluat-
ing their survival and, therefore providing insight about optimal size at release for
hatchery juveniles, it is necessary to know exact dates of smolt transformation in
the given population.
    An evaluation of physiological readiness for life at sea for hatchery juvenile
chum salmon, raised in two different regions of Kamchatka – on the south-eastern
seashore and in the mountainous Central district – showed a fundamental differ-
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