Discussion of the problems encountered in 

 holding adults in the concrete pond at Carson 

 hatchery is presented later in this report. 



Data pertaining to losses of fish held in the 

 dirt holding pond in period 1955-61 are given 

 in table 3 and Appendix tables A-1 — A-7. 



Greatest loss of fish held in the dirt holding 

 pond occurred in 1957--30.2 percent. This was 

 the year of highest water temperatures 

 (table 3). 



Eggs collected from adults held in the dirt 

 holding pond have varied from 330,700 in 

 1959, when 184 fish were transferred from 

 Bonneville Dam, to 1,259,300 in 1961, when 

 545 fish were transferred to Carson hatchery. 



Information regarding losses during incuba- 

 tion of eggs and rearing of fingerlings is 

 given in table 4. 



Concrete pond . — The concrete holding pond 

 at Carson hatchery is used as a ripening 

 area for those adult spring chinook salmon 



that return to their point of release (fig. 4). 

 The pond is 146 feet long and 40 feet wide, 

 with concrete sides and bottom. Normal depth 

 of water in the pond during the salmon maturing 

 period is 3.5 feet. Water from Tyee Springs is 

 introduced through a diffusion chamber located 

 on the bottom near the upper end of the pond. 

 When needed, additional flow is introduced from 

 Wind River. Water from the fingerling rearing 

 ponds also passes through the adult holding 

 ponds. Daily maximum and minimum tempera- 

 tures of the water in the pond are available for 

 1961 (Appendix table A-9). 



In 1957, 62 spring chinook salmon trapped 

 at Bonneville Dam were held in the concrete 

 holding pond at the hatchery (table 5). Of this 

 number, 15 fish (24.2 percent) died in the 

 trap or pond, were killed before sexually 

 mature, or had diseased ovaries. In this same 

 year, 364 fish were held in the dirt pond, 

 and similar losses amounted to 110 fish 

 (30.2 percent). 



In 1959, 107 chinook salmon entered the 

 concrete holding pond from Wind River (table 5). 



Table 4-. — Losses incurred during artificial rearing of spring chinook salmon resulting from 

 spawning of adults held In dirt holding pond, Carson National Fish Hatchery, 1955-61. 



""" Includes losses in fingerlings partially reared at Little White Salmon and Willard hatcheries. 

 ^ Includes eggs taken from fish held in concrete pond. 



^ Rearing losses of the 50,000 unfed fry shipped to Happy Valley Reservoir not included. 

 "^ Rearing losses of the 75,300 unfed fry transferred to Happy Valley Reservoir not included. 

 Rearing losses of the 56,900 fingerlings provided for Bonneville Dam experiments are included. 



