Table 3. — Areas where catches were examined for marked fall chinook salmon of Columbia River origin by port or zone of 



landing and type of fishery 



hatchery output. For this reason, Y>\a,ns for mark 

 sampling also included examining the fish return- 

 ing to the hatcheries and searching for marked 

 fish on certain natural spawning grounds. 



Fish returning to tlie hatcheries are counted 

 and e-xamiiK'd for marks. At each hatchery an 

 effort is made to obtain data on age, length, and 

 sex for 25 to 50 unmarked fish per week. In addi- 

 tion to searcliing for marks at tlie 12 participating 

 hatcheries, returns to 5 other hatcheries (Aber- 

 nathy, Speelyai, Toutle, Klaskanine, and Sandy; 

 fig. 1 ) are also examined for marks. 



To estimate natural spawning of hatchery- 

 reared fish, surveys were conducted on h;vtchery 

 streams as well as those adjacent to or near the 

 hatcheries under study. Tliese streams are Klicki- 

 tat, liig AVhite Salinon, Little Wliite Salmon, 

 Wind, Washougal, Kalama, Lewis, Elokomin, and 

 Grays Rivers and Plynqfton and Big Creeks. 

 These surveys were designed to estimate size of the 

 total spawning iMjpulation, as well as to sample 

 for marks, age, and length. 



All data collected during the recovery phase of 

 the study are recorded on a standard form (fig. 4). 

 Data on a group of fish examiiunl for marks are 

 recorded acctn-ding to tiie format along the upper 

 part of the form; data for individual marked re- 

 coveries are recorded on the same form according 

 to the format along the lower i>art. A scale sam- 

 ple from each nuirked fisii is sent along with the 



form to the Fish Commission of Oregon's mark 

 processing center, where the age is determined 

 and entered on the fonn. * Samples of individual 

 unmarked fish are I'ecorded and processed in the 

 same way as the marked fish. 



After approi)riate coding (e.g., type of mark, 

 fishery and gear, and port of landing) the data 

 are transferred to data processing cards from 

 which tabulations are made. The tabulations are 

 tlien foiwtirded to the Biometrics Unit at the 

 ]5iireau of Coiiiiiiercial P^isheries Biological I.ial)- 

 oratory, .Seattle, Wash., wiiere they are collated 

 with catch information, and a summary report of 

 cm-h year's sampling effort is assembled. 



SOURCES OF VARIATION 



Two major sources of variation in tlie contribu- 

 tion of hatcheries are being considered. The lirst 

 is the \ariation from year to year, which is the 

 reason for extending the marking experiment 

 o\er four brood years. The second source of \aria- 

 tion is among hatcheries. To examine this, a group 

 of fish at each of the four hatcheries was marked 

 with a uni([ue fin clip each year. Sj)ring Creek and 

 Kalama Ilatcln-ries were allotted a special mark 

 each year, and two additiomd special marks were 

 rotated among eight of the remaining hatcheries 

 so all hatcheries, except two, recei\ed special 



* In some instances (British Columbia ami Washington fish- 

 eries), a^es are determined by the agency tliat collects the data. 



366 



U.S. FISII AXP WILDLIFE SERVICE 



