FISHERY BULLETIN: VOL. 70, NO. I 



Table 7. — Percentage frequency distribution' of circuli in the first ocean zone of age 2. sockeye salmon collected 



in various years from 1956 to 1967. 



KEY TO THE PLATES 



To compensate for the reduction of the original 

 scale photographs to fit the printed page, use a 

 3 to 5x reading or magnifying glass to study 

 them. 



The area enclosed by the first or central circu- 

 lus is the focus or central platelet of the scale. 



The long black pointers near the focus indi- 

 cate winter marks in the freshwater growth zone. 



A black stub pointer, if present, indicates the 

 end of plus or transitional growth. If plus 

 growth is i)resent, the circuli between the outer- 

 most long black pointer and the black stub point- 

 er are plus growth circuli. If no plus growth is 

 present, the outermost black pointer indicates 



the end of freshwater growth as well as the last 

 winter in fresh water. 



The white pointers bordered by black indicate 

 the first winter mark in the ocean growth. The 

 circuli between the end of the freshwater growth 

 (or plus growth, if present) and this pointer are 

 ocean-growth circuli and record the first year's 

 growth in the ocean (the first ocean growth 

 zone). The more widely spread circuli of this 

 zone were deposited from May or June to Sep- 

 tember or October (the summer growth) , where- 

 as the more closely spaced circuli near the pointer 

 were deposited during the autumn, winter, and 

 early spring months (the winter growth). 



If a small white pointer'is present, it indicates 

 an adventitious check in the first ocean growth 



150 



