FISHERY BULLETIN OF THE FISH AND WILDLIFE SERVICE 



269 



In figures 8 and 9 is presented the relationship between the percentage of fish 

 of a particular fresh-water history in the escapement and the percentage of fish of the 

 same fresh-water history in the return. There is a positive correlation between the 

 the two variables, although the relationship is very peculiar. For each 1 percent of 

 three-fresh-water fish in the escapement there is approximately 0.75 percent of three- 

 fresh-water fish in the return, and for each 1 percent of four- fresh- water fish in the 



20 40 60 BO 



PERCENTAGE Of TWO-OCEAN FISH IN ESCAPEMENT 



Figube 6.— Percentage of two-ocean fish in return plotted acainst percentage ol two-ocean fish in escapement for Hie years 1922 and 

 1921 to 1929, inclusive. The straight line represents a ratio of 1 to 1. 



escapement there is more than 2 percent of four-fresh-water fish in ilio return. Such 



a condition could not have prevailed for any great length of time. Obviously, if such 

 a relationship bad existed for several complete cycles, tin- three-fresh-water fish would 

 disappear from the population and only those that migrate to the ocean in their fourth 

 year would remain. 



The age analysis based on scale samples collected during 191o, 1017, 1010, and 

 1921 (Gilbert and Rich, 1027), demonstrated 88.5, 88.1, 01.3, and 93.4 percent, 







%> 





