FISHERY BULLETIN OF THE FISH AND WILDLIFE SERVICE 293 



8. A negative correlation exists between escapement and surplus which might 

 indicate that most of the escapements have been too large. This suggestion is believed 

 to be untrue. The negative correlation is related to adverse factors influencing the 

 survival value. 



9. While the affluents of Karluk Lake contained appreciable amounts of phos- 

 phorus and silica, during the summer months, less than a measurable quantity of 

 these inorganic salts were present in the lake water, indicating that they are limiting 

 factors in the production of phytoplankton and indirectly of the zooplankton of 

 Karluk Lake. As the lack of these inorganic salts indirectly affects the production 

 of zooplankton it is probable that it also indirectly affects the growth and survival 

 of young red salmon which depend, to a large extent, on the zooplankton as a source 

 of food. 



10. Little change, if any, is taking place in the relationship between the percent- 

 age of fish of a certain ocean history in the escapement and the percentage of fish of 

 the same ocean history in the return. However, a marked change is occurring in 

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

 tion to the percentage of fish of the same fresh-water history in the return. This 

 relationship is quite unusual, and though evidently existent during most of the 

 period of time under consideration could not possibly have existed for any great 

 length of time in the past. Unless the relationship changes, the majority of the fish 

 in the Karluk runs will be four-fresh-water fish, whereas formerly the three-fresh- 

 water age group was dominant. 



11. The change in the period of time spent in fresh water is considered to be due 

 to unfavorable environmental conditions, which may also adversely affect the sur- 

 vival value of the population. 



12. The seaward migration of Karluk red salmon takes place during the last 

 week of May and the first 2 weeks of June. 



13. The percentage of 4-year fingerlings decreases, and the percentage of 3-year 

 fingerlings increases, during the period of the migration. 



14. The time of seaward migration depends on the growth rate of the finger- 

 lings, the fastest growing individuals migrating first. 



15. Among the seaward migrants the males and females arc equally represented. 



16. Among the adult fish there is a greater proportion of females than males. 



17. There is a decrease in the percentage of males among the adult fish, with 

 increased ocean residence. 



18. Among the fish of a single ocean history, there is usually a decrease in the 

 percentage of males with increased total age. 



19. The returns from the marking experiments at Karluk have been consist- 

 ently greater than returns from similar experiments in other areas. This is probably 

 true because the Karluk seaward migrants were larger at the time of marking and 

 migration than the fish in similar experiments in other areas. 



20. A greater return, or survival, was found among the older and larger 4-year 

 migrants than among the 3-year migrants. 



21. Although the ocean survival is greatest for fish that have had the longest 

 lake residence, these fish suffer a greater mortality in fresh water due to the longer 

 residence in the lake. 



