Table 10. — Estimated number of marked fall chinook salmon of 1981 brood in catches, Iribidary spawning populations, and 

 hatchery returns by type of mark, region of recovery, type of fishery, and year of capture, 1963-66 — Continued 



' Primarily troll fisheries. 



- Primarily pill net. 



s Twelve hatcheries participating in the marking program. 



< ToutU", Abernathv. Speelyai, Sandy, and Klaskanine Hatcheries. 



Table 10. — Eslimaled number of marked fall chinook salmon'of 1961 brood in catches, tributary spawning populations, and 

 hatchery returns by type of mark, region of recovery, type of fishery, and year of capture, 1963-66 — Continued 



•Not sampled. 



> Primarily troll fisheries. 



- Primarily gill net. 



3 Twelve hatcheries participating in the marking program. 



' Toutle, Abernathy, Speelyai, Sandy, and Klaskanine Hatcheries. 



examination of the data on mark recoveries and 

 accuracy of deterniinino- the age of fall chinook 

 salmon. 



In test readings of scales from marked chinook 

 salmon of known age, six scale readers correctly 

 aged (total age) 9<?> percent of the 400 test scales 

 (Godfrey, Worlund, and Bilton, 1968). Table 11 

 shows the estimated and actual percentage age 



compositions of the 400 test scales. From the re- 

 sults of this test, it appears that in any one year 

 scale readers can estimate reasonably well the 

 numbers of i^artially marked fish of a given age 

 (and, hence, brood-year) . 



A summary of partially marked fish is presented 

 in table 12 ; the data resulted from the combination 

 of years and general mark types (e.g., Ad-LV and 



COXTRIBUTIOX OF COLTMBIA RIVER HATCHERIES TO FALL CHINOOK SALMON HARVEST 



377 



