with no evidence of overcrowding. On this basis, 

 25,000 pounds would be a fair estimate of the 

 density at which the pond could be stocked. The 

 volume of water introduced is more than ade - 

 quate to meet the oxygen requirements of the 

 fish. Fingerling chinook salmon require 0.5 

 ppm of oxygen per pound of fish per gallon of 

 water inflow at a water temperature of 57° F. to 

 maintain a normal activity level . There is no 

 reason to assume that large adult salmon in 

 practically a dormant condition will exceed the 

 oxygen demand of fast growing, normally active 

 fingerling even at water temperatures of 70° F. . 

 Fry (1957) demonstrates that while the oxygen 

 consumption in trout increases with temperature 

 it also decreases much more rapidly, per unit 

 of weight, with an increase in fish size. In 

 chinook salmon fingerling the oxygen require- 

 ment increases .025 ppm per pound of fish per 

 gpm per degree F. from 47° F. to 57° F. To 

 provide an adequate margin of safety the oxygen 

 requirement of the chinook fingerling at 57° F. 

 was used to calculate the carrying capacity of 

 the inflowing water for the adult fish . On this 

 basis it is estimated that 35 cfs of oxygen-sat- 

 urated water at 70° F. will maintain 126,000 

 pounds of salmon, i.e., 5,000, 25 -pound chinook 

 or 21,000, 6 -pound blueback salmon, without 

 additional aeration and still leave 5 ppm of oxy- 

 gen at the outflow . Such an inflow would be 

 more than adequate to prevent the accumulation 

 of deleterious concentrations of excretory 

 products as the fish are not feeding and practic- 

 ally quiescent. 



A single pond of the dimensions shown 

 in fig. 1 could not handle the carrying capacity 

 of the water supply without exceeding the es- 

 timated capacity of the pond. There is no 

 reason, however, why such ponds cannot be run 

 in series and, with adequate aeration between 

 ponds, the actual carrying capacity of the inflow 

 increased. 



Ponds in series: --Figure 2 shows the 

 layout for a series of holding ponds of the chan- 

 nel type . In this plan the fish are directed into 

 the individual ponds but move of their own voli- 

 tion. Once the fish are diverted into the fish 

 ladder they are offered but a single upstream 

 course to pursue . The earliest appearing fish 

 are diverted into the upper pond by proceeding 

 up the right fish ladder . When the capcity of 



this pond is reached the course of the water is 

 changed by activating the second pond and the 

 fish proceed up the left fish ladder . In figure 2, 

 the next to last pond is fishing and the last pond 

 is still inactive. 



The number of ponds that would constitute 

 a series would be dependent not only on the carry- 

 ing capacity of the water supply but on the con- 

 centration and virulence of the disease organisms 

 in the last ponds of a series. High water temper- 

 atures could be expected to increase the virulence 

 of diseases. An infected water source would in- 

 crease the incidence of disease . The condition 

 of the fish as they entered the ponds and the length 

 of the holding period would have a significant ef- 

 fect on the survival rate and the number of pbnds 

 used in series. With water temperatures in the 

 low seventies and a preinfected stock, I would 

 estimate that at least four ponds could be operated 

 in series. Under more favorable conditions, such 

 as water temperatures in the low sixties, I be- 

 lieve that six and possibly eight ponds could be 

 operated in a single series with a 35 cfs inflow. 



Adaptations: --With a smaller inflow avail- 

 able the holding pond may be reduced in cross- 

 sectional area to maintain the desired .2 fps of 

 average velocity. The maximum practical re- 

 duction would be a pond 25 feet wide by 3 feet 

 deep, increasing the length to 200 feet, but re- 

 taining the 3 on 1 slope of the banks . Such a 

 pond would have a cross-sectional area of 48 

 square feet and require approximately 10 cfs of 

 inflow. The holding capacity of this pond, based 

 on the area of water 3 feet in depth as compared 

 to the area 3 feet or more in depth in the large 

 pond, would be 30 percent of the larger pond. 

 Area rather than volume was used as the criter- 

 ion because the fish tend to stratify in a single 

 layer rather than utilize the entire pond volume. 

 On this basis, the small pond should hold approx- 

 imately 7,500 pounds of fish. The carrying 

 capacity of the 10 cfs water supply, however, is 

 36,000 pounds. Smaller ponds in series, then, 

 could be employed to use the total capacity of the 

 water supply. It will be noted that the length of 

 the smaller pond has been increased to 200 feet. 

 The increase in pond length is desirable in order 

 to more efficiently utilize the trapping facilities . 



If large numbers of fish, different species, 

 or races within a species are to be held , the use 



