The feeding schedule was not rigidly main- 

 tained during the final week of the 1959 experi- 

 ment due to the press of the fish planting 

 operation. Care was exerted to avoid a re- 

 currence of this in 1960. 



Starvation, as it is referred to in this re- 

 port, is defined as the cessation of artificial 

 feeding. Although we did not measure the 

 plankton in the water supply, we do not be- 

 lieve that it was of sufficient quantity to affect 

 the results. This belief is supported by previous 

 chemical and plankton data (unpublished). 



Sampling 



All sampling was done with a quartering 

 net (fig. 1) which was developed, evaluated, 

 and described by Hewitt and Burrows (1948). 

 The operation of the device is as follows: 

 First, the net with one of the four bobinetting 

 bags tied closed is placed flat on the bottom 

 of a half-filled washtub. The population to be 

 sampled is transferred from the trough to the 

 tub and dispersed by three gentle clockwise 

 rotations of the hand after which the net is 

 quickly raised thereby trapping the fish in the 

 closed bag. Fish which fall into the three un- 

 tied bags remain in the tub. Sample size can 

 be increased by closing additional bags or 

 reduced by repeating the process on the initial 

 sample. 



The fish in the samples were anesthetized 

 in a 1/20,000 solution of MS222; fork length 



Figure 1. --Quartering net. 



to the nearest millimeter and weight to the 

 nearest gram recorded from each fish; and 

 scales selected from a position just below 

 the insertion of the dorsal fin. To eliminate 

 the possibility that anesthetized fish might in- 

 fluence the experimental results, all samples 

 were removed from the experiment. 



Scale analysis 



Several scales from each of 10 fish were 

 mounted dry between a pair of glass slides. 

 The ends of the slides were secured with 

 masking tape, and the slides appropriately 

 labeled. Scales were examined microscopically 

 at a magnification of 83 diameters. 



Starvation is reflected upon the scales of 

 hatchery-reared sockeye salmon by two or 

 three faint, closely set, and often broken 

 circuli. The recognition of these circuli is 

 dependent on their contrast with the surround- 

 ing circuli pattern. Scales from slow grow- 

 ing fish, therefore, do not reflect the effects 

 of starvation as do scales from rapidly grow- 

 ing fish. Most of the experimental fish, typical 

 of hatchery-reared salmon, were rapidly grow- 

 ing fish; consequently, starvation induced an 

 abrupt, hence easily recognized, change. How- 

 ever, even fish that grew rapidly both before 

 and after starvation did not reflect the mark 

 in significant numbers until 2 to 4 weeks after 

 they had resumed feeding. The position of the 

 mark, relative to the center and edge of the 

 scale, is dependent upon the amount of pre- 

 starvation and poststarvation growth. Pre- 

 liminary observations revealed no apparent 

 difference in the intensity of the marks in- 

 duced by the various starvation intervals. 

 Figure 2 contains photographs of typical scales 

 from starved and control fish. 



Because of the criteria employed to deter- 

 mine whether the scales of an individual fish 

 were marked were entirely visual and some- 

 what subjective, we felt that personal bias 

 must be reduced. To accomplish this we read 

 all scales without reference to other scales 

 on the slide and without knowing the feeding 

 history of the fish bearing the scales. This 

 was done by assigning a code number to the 

 back of each slide and then changing the slides 

 after each individual reading. 



