Table 2. — Ages of marked Columbia River fall chinook 

 salmon in catches and escapements by brood (lOGl-GJ,) 

 and sampling years {1963-60) 



RM 



Ad-RV- Kalama 



RM 



RV-RM Ox Bow - 



LV-RM Elokomin 



1962.. Ad-LM 12 hatcheries.. 



Ad-L\'- Spring Creek.. 



LM 



Ad-RV- Kalama. 



LM 



RV-LM Cascade 



LV-LM Urays River. . 



1963.. Ad-RM 12 hatcheries.. 



Ad-LV- Spring Creek.. 



RM 



.\d-RV- Kalama. 



RM 



RV-RM Klickitat 



LV-RM Big Creek 



1964-. Ad-LM 12 hatcheries.. 



Ad-LV- Spring Creek,. 



LM 



.\d-RV- Kalama 



LM 



RV-LM Little White 



Salmon. 



LV-LM Bonneville.. - 



Number of marks in catches and 

 escapements 



3 4 5 



3 4 5 



3 4 5 



2 3 4 5 . 



2 3 4 5 



3 4 5 



3 4 5 



2 3 4 6 



2 3 4 5 



2 3 4 5 



3 4 5 



3 4 5 



2 3 4 5 



2 3 4 5 



2 3 4 6 



I Ad: Adipose; LV: Left ventral; RV: Right ventral; LM: Left maxillary; 

 RM: Right maxillary. 



To obtain the fish for nuuking, a sampling tool 

 (Hewitt and Burrows, 1!)4S) was modified to re- 

 move a random "10 percent" sample. Tliis device is 

 a circular net consisting of 10 equal pie-shaped 

 sections that fits into a cylindrical liner such that 

 all fish contained in the cylinder must pass through 

 one of the sections (fig. 2). The sample for mark- 

 ing was obtained by closing one of the sections. 

 In practice, the sampling device was placed in a 

 tub partially filled with water. Fish were removed 

 from a pond in groups weighing about 18 kg. (40 

 pounds) each and placed in the sampler, and the 

 device was then raised; the closed section retained 

 the sample for marking. The fish that passed 

 through the open sections remained in the tub and 

 were placed in another pond. This procedure was 

 followed until all fish in each pond were {Processed. 



At each hatchery, fish selected for marking were 

 first anaesthetized with MS-22'2 ^ (tricaine meth- 

 anesulfonate), then the markers used bent-nosed 

 dissecting scissors to remoxe certain fins and maxil- 

 laries. Marked fish were held in hatchery troughs 



2 Trade namps referred to in this pnlilication do not imply 

 endorsement of commercial prodncts by the Bureau of Com- 

 mercial Fisheries. 



364 



for recovery from the anaestlietic and returneil to 

 the group of unmarked fish from which they were 

 removed. To ensure proper control of quality, 25 

 marked fish from each marker were examined 

 daily. In addition, fish that died shortly after 

 marking were carefully examined in an eti'ort to 

 detect improper handling. 



The entire production of each hatchery was 

 sampled at time of release (3-8 weeks after mark- 

 ing) to estimate the proportion and numbers of 

 marked fi.sh released. The procedure for obtaining 

 this sample was the same as for selecting fish for 

 marking, except that fish initially removed by the 

 closed section of the sampler were pooled and 

 •sampled again. The resultant sample ( about 1 per- 

 cent of the total production) was sorted into 

 marked and unmarked groups and counted and 

 weighed. These counts, together with an estimate 

 of the proportion removed by the particular 

 sampler, were used to estimate the proportions and 

 niinibers of marked fish in the release. 



RECOVERY OF MARKS 



The recovery phase of the investigation began 

 in VMV.\ and will end in liXi!) (table 2). 



Sami)ling for marked fish was designed to cover 

 four areas: major ocean fisheries from southeast 

 Alaska tt) central California, Columbia River fish- 

 eries, parent hatcheries, and certain natural spawn- 

 ing grounds. 



Sami)ling for marks in each area consists of 

 i-ecoi-tling numbers of fish examined for marks and 

 the numbers recovered with each type of mark. 

 In addition, all marked fish and a sample of un- 

 marked fish are examined for age, length, and 

 weight. It was recognized that occurrence of marks 

 and compositions of age and size woukl change 

 with time; thus, the sampling sea.son was stratified 

 into small units (usually biweekly for the ocean 

 and weekly for the Columbia River fisheries). 



The general fisheries being sampled are ocean 

 commercial and sport; Columbia River commer- 

 cial and sport; and Puget Sound sport. For pur- 

 poses of sampling, most fisheries were further 

 stratified by port of landing. Exceptions are the 

 Alaska and British Columbia troll, purse seine, 

 and gill net fisheries; Columbia River commercial 

 and si)ort fisheries; and Puget Sound sport fishery, 

 in which the stratification is by area of catch. The 

 specific fisheries being sampled are listed in table 



U.S. FISH AND WILDLIFE SERVICE 



