5400 
5000 
4600 
NUMBER OF EGGS 
4200 
3800 
— 1966 pectoral marks excluded 
—— — 1966 pectoral marks included 
YEAR 
Figure 24. Trend of fecundity on return year 
of three-year-old Chinook salmon females. 
average increase was about 200 eggs per female, 
from 1960 through 1967. 
Sea survival of the Chinook salmon has been 
good, returns exceeding 1 per cent of the finger- 
lings released (1.0 to 3.25 per cent). The program 
has now become stabilized; 250,000 select finger- 
lings are released each year and 2.5 to 5 million 
eggs are obtained when the fish return. Five to 10 
per cent are selected to continue the select stock. 
Excess eggs and fingerlings are transferred to other 
streams, where we hope they will contribute to 
commercial and sport fisheries. 
4. Trout 
A program of selective breeding of rainbow 
trout has been carried on at the University of 
Washington’s College of Fisheries for the past 36 
years. Changes during the past 13 years have been 
pronounced (Figure 25). When the program was 
initiated in 1932 the trout reached maturity in 
their fourth year at an average weight of 1% 
pounds and produced 400 to 500 eggs at their first 
spawning. 
After 36 years, the males of select stock reach 
maturity in the first year and the females all 
mature in the second year. The rate of growth also 
VI-158 
has changed dramatically. In 1944, the first year a 
fair number of spawning fish of the two-year age 
class was available, the fish averaged 36.3 centi- 
meters forked length. By 1968, the average length 
for two-year-old spawning rainbow trout had 
increased to 60.4 centimeters, an average increase 
of a centimeter a year. The three-year-old 
spawners in the past 14 years (1954 to 1968) have 
increased from 50.5 centimeters forked length to 
68.1 centimeters, an average annual increase of 
1.25 centimeters. An actual example (Figure 26) 
shows the results of controlled rearing techniques. 
B. Future Needs 
There is a need to develop an integrated 
systems approach to the field of aquaculture, 
consisting of effective collection, trapping, hatch- 
ing, stowage, and processing facilities. If such a 
system were adopted, industry would be able to 
contribute heavily to expand the program. An 
example of the systems approach is found in the 
oyster industry. 
Suspended culture of oysters is performed now 
in small areas, the oysters growing on strings 
suspended from floating rafts or underwater racks. 
Seeding the oysters, setting the racks or rafts, and 
harvesting are hand operations. It is technically 
possible to make racks (with suitable oyster 
attachment materials already in place) to be 
installed by hand but seeded automatically from 
nearby seed beds. Properly designed, an entire rack 
could be conveyed to a harvesting device for 
removing the mature oysters mechanically or 
hydraulically, sorting them and packing them in 
one continuous operation. 
The entire growing medium could be regulated, 
using three-dimensional units and controlling the 
oysters’ growth with properly regulated water and 
nutrient flows. The engineer would work closely 
with the marine biologist who would determine 
optimum temperature, nutrient level, and water 
turnover required to maximize shellfish growth 
and quality. 
He would treat the oyster farm as a system 
(including both the physical and biological param- 
eters established by the marine biologist and the 
economic limitations imposed by product value 
and the local labor market) to achieve the best rate 
of return on investment. In a region of high labor 
costs, the environmental control system might 
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