Íslenskar landbúnaðarrannsóknir - 01.09.1978, Blaðsíða 117

AN ANALYSIS OF KOLLAFJORDUR HATCHERY 1 15
(iSalvelinus alpinus), Atlantic salmon (Salrno
salar) is the principal product and is the
only species considered in this paper.
Kollafjördur Hatchery and its operat-
ing procedures are described by Gud-
jónsson (1973). Briefly, the hatchery op-
eration is as follows: adult salmon return
to the hatchery from June through Sep-
tember and are held until late October,
when stripping takes fílace. If incubated
in unheated water, the eggs hatch in
Jan uary and the alevins begin feeding in
late May; with the use of heated water, the
date offeeding can be advanced as much
as 4 months.
Once feeding starts, the fry are placed
in one of40, 2 m X 2 m fiberglass tanks in a
first-stage rearing house. The water is
heated and varies between 8° and 13°C.
The fish are continually fed as much food
as they will eat. Fish in the first-stage
rearing house may be sold, transferred to a
second-stage rearing house, or transferred
to outdoor ponds.
The second-stage rearing house is co-
vered with a transparent rood to insure
proper photoperiod prior to smoltifica-
tion. The ponds in this house consist of 12,
15-m long concrete raceways. Eight are
1.9 m wide and 4 are 0.6 m wide. Enough
hot water is available to maintain two
large ponds at 10°C; the temperature of
the remaining ponds varies between 3°
and 6°C. Salmon raised in the heated wa-
ter reach smolt size and can be released in
May and June. The other fish must be
held for another year, transferred to an
outdoor pond, or sold. In both the first-
and second-stage rearing houses fish are
regularly graded, and fish of similar size
are placed in the same pond.
There are 27 earthen outdoor ponds, 6
of which are commonly reserved for sal-
mon. Fifteen of the 27 ponds are shallow
and have been little-used so far for any
species. Salmon are placed in the outdoor
ponds in the fall after reaching a size ofat
least 10 cm indoors. Over-winter mor-
tality is significant, but a large number
survive and are released as 2-yr. smolts.
Others are sold.
Fish leave the hatchery when they are
sold to buyers to supplement natural pro-
duction of private streams, when they are
planted into barren or experimetal
streams, or when they are released at the
hatchery.
Fish released at Kollafjördur return to
the hatchery after either one (90%) or two
(10%) winters at sea. Some are selected
for brood slock and held, while the rest are
slaughtered and sold to support the
hatchery’s operations.
Three sources of water are important to
the hatchery. Springwater with .a volume
suíficient for all the hatchery’s needs
(150-200 liters/sec) is most important. Its
temperature varies between 3°C in the
winter and 6°C in the summer. The sec-
ond source of importance is 5—8 liters/sec
of 70°C thermal water. This water goes
through a heat-exchanger and warms a
part of the springwater. Additional hot
water could be made available with a
certain amount of capital expenditure. A
third source of water is a stream with a
relatively large wolume of water. Its
temperature varies between 1°C in the
winter and 10°C in the summer. The
stream is presently being used only on an
experimental basis, with the hope that its
high summer temperature can be used
advantageously to increase growth. The
mean monthly temperatures of the well