Body length of the fish was measured as described by Sette (I9UI). For each 

 sample, scales were obtained from the first 10 specimens having any still at- 

 tached. Generally about 10 or 12 scales were taken from the side of the body 

 near the region touched by the tip of the pectoral fin. As necessity, required, 

 however, fewer were taken, sometimes only one, and from v/herevcr they could 

 be found. 



As the scales were collected from each fish they were placed in a small 

 vial of water to which had been added about two drops of 2 percent phenol 

 for preservative. The vials were kept in covered trays, 50 to a tray, and 

 held in numbered places by round slots bored in the bottom. The collections 

 v;ere sent daily to the laboratory at Stanford University, where they were 

 mounted. 



Generally the field man assigned to the sampling work was able to take 

 five samples daily, that is scales from 50 fishi'. In Washington, whenever 

 the landings were too few to permit collection of this number of samples, 

 scales were taken from enough spociraens to brin;^, up to that time, the daily 

 average to ^0. 



In the laboratory'-, the scales vrerc cleaned and dried by rubbing between 

 the fingers, and mounted between tv/o dry, clean slides which viere then bound 

 together at the ends ^irith cellixLose tape. The mounted scales were examined 

 vfith the aid of a projecting microscope. For each specimen a paper strip 

 printed vj-ith a millimeter me.asure v:as laid on the image along the midlongi- 

 tudinal axis of the sculptured part of the scale with the zero line at the 

 base of the sculptured part. Locations of annuli v/erc traced on the paper 

 strip and later recorded as dimensions after reading the millimeter measure. 



These as vrell as such pertinent data as sample number, length, and sex 

 of fish, locality and date of collection, name of reader, dimensions of scale, 

 position of marks, calculated length of fish at past ages, etc., were recorded 

 on a punch card, providing a permanent detailed record for every scale reading. 



It required tv/o hours for one person to mount 50 scale samples^ two hours 

 for one person to read ^0, and about four hours for one person to tabulate 

 the data, calculate growth increments, pvinch the cards, and check these steps 

 for $0 readings. Thus the routine processes in the laboratory required about 

 eight man hours for one day's field collection from one port. 



The readings Virerc all done by the authors, 'j/ith certain exceptions, to 

 be discussed below, each examined alternate samples of scales, Pfelford the 

 odd-numbered ones, Ifosher the even. 3y this method a check could be furnished 

 on each man's reading, since the two sets, on theoretical grounds, should be 

 satistically homogeneous if the operators used identical standards for inter- 

 preting annuli. The results of this check will be disciissed below. 



Occasionally the scale collection from a specimen was obviously contam- 

 inated with one or more scales from other fish. V/hcn that occurred, the ma- 

 terial was discarded unless at least three quarters of the scales were obvi- 

 ously from the same fish, in v/hich case these were read. 



1/ Beginning with the 19U1-U2 season, an off ort vras made to sample approxi- 

 mately one-fifth of the landings. 



99 



