PROGRESS IN BIOLOGICAL INQUIRIES, 1985 443 



by the removal of both ventral fins and planted in the West Fork of 

 Beavei- Creek. This planting; of marked iish was made with the dual 

 purpose in view of comparing; the more detailed findin<>s made at 

 Waddell Creek with the somewhat different conditions found on the 

 Klamatli, and of establishing an annual run of marked fish which 

 would give some indication of the varying intensity of fishing in the 

 main stream below. 



In ]May tlie ponds at the Hot Creek station were drawn down and 

 the survivors of the select lots of fingerlings that had been i)lanted in 

 the previous July and August were netted out, graded, and the best 

 retained for brood-stock purposes. An average survival rate of 23.36 

 percent obtained after a period of api)roximately 9 months in the 

 four natural ponds used. A total of 27,300 pedigreed trout weighing 

 717 pounds were planted in nearby waters from the Hot Creek 

 ponds this year. 



The number of select brood stock held for experimental breeding 

 purposes now total 1,597 fish, representing five different strains of 

 rainbovv'. The majority of these fish will reach spaAvning age in the 

 fall and winter of 1936-37, when actual selective breeding tests will 

 be started. 



Remarkable growth rates have obtained in spring water at Hot 

 Creek at 63° F. On natural foods, starting with fish between 2 and 

 3 inches long, growth avei-aged approximately half an inch per 

 month. In a feeding experiment 100 rainbow averaging 5 inches in 

 length were fed a diet of 30 percent li^er (fresh weight), 35 percent 

 salmon egg meal, and 35 percent abalone chips. Under the regime, 

 growth averaged approximately 1 inch a month. Anotlier lot of the 

 same size and kind of fish held under identical conditions, but fed only 

 pure shrimp collected from watercress beds grew on the average 

 0.82 inch per months. The experiments with both lots of fish 

 were run for a period of 85 days. It required 3 pounds of the 

 liver — salmon egg meal — abalone chips diet to produce a pound of 

 trout at a cost of $0.28 per pound of trout raised. The cost of this 

 diet was $0,084 per pound. It required 9.57 pounds of shrimp (v.et 

 w^eight) to produce a pound of trout in the shrimp fed lot. 



Excellent returns were obtained from the Angora Lake j^lanting 

 experiment this year, 136 catches, yielding 809 trout, being recorded. 

 Marked fish of the 1933 and 1935 plants combined formed 77 percent 

 of the 809 caught in 1935. Only 23 percent of tlie catch were un- 

 marked trout. No marked trout were caught prior to the 1935 fish- 

 ing season. The average catch per angler in 1934 was 2.3 fish and 

 in 1935, 5.9 fish. 



A plant of 2,014 marked rainbow trout averaging 5.67 inches in 

 length was made in Convict Lake on July 20, 1935. The object of 

 this plant was the same as those made in Angora Lake ; viz, to com- 

 pare numbers actually taken by anglers with numbers planted. An- 

 other object was to test a new system of boat records from whicli 

 the catch per unit of effort from year to year could be determined. 



The results obtained are most promising. The catch per unit of 

 effort ^ was determined as 0.21 fish per hour per angler. Boat fisher- 

 men filled out 106 catch-record blanks. Only 50 percent of the 

 parties renting boats actually caught fish. For those taking trout 



*> Here "catch per unit of effort" is not the .same as •'catch per fishing effort" defined on 

 p. 440. 



