Íslenskar landbúnaðarrannsóknir - 01.09.1978, Page 120

118 ÍSLENZKAR LANDBÚNAÐARRANNSÓKNIR
leasl 10 cm long when placed in the out-
door ponds. Physical constraints include
the number of ponds available and the
amount of heated water and its tempera-
ture.
Analysis of hatchery operations
A method used to examine possible man-
agement schemes for Kollaijördur Hatch-
ery calls for filling in various boxes of the
chart shown in Fig. 4. The boxes represent
blocks of water available during each
month of the year. Into each box is placed
fish size in grams at the beginning of the
month, and the number of fish to be held.
Certain rules reflecting hatchery practices
govern how blocks are filled in. Initially,
simple rules were used, but these can be
refined when greater knowledge becomes
available and when more precision is de-
sired:
1. Fish start feeding between February 1
and June 1 at a size of 0.25 g.
2. Fish are raised in heated water at least
until they reach a size of 1 g.
3. In heated water (about 10°C) fish
grow exponentially from 0.25 g to 50 g
in 11 months. The monthly schedule
is the0.25, 0.4, 0.7, 1.1, 1.7, 2.8, 4.5,
7.3, 11.8, 19.1, 30.9, 50.0.
4. Growth in unheated water is insig-
nificant.
5. The number of fish per unit of water
may not exceed the schedule shown in
Table 1. (The number of fish at the
beginning of the month may not ex-
ceed the number of fish which can be
held at the weight obtained by the
month’s end.)
6. Fish destined to be 1-year smolts must