Have a peculiar question about how long a mature salmon can live in rivers and lakes before finally dying. Read that it is usually around 5-6 weeks or so with most runs. I guess it depends on species and population of course. One run that comes to mind are those Kenai winter silvers. They must really load up on fat before going up the river since they will spend several months swimming around. Why don't they just wait it out in the ocean and then run upstream to spawn? Any other runs that do the same sort of thing?