I am trying to find an alpine cirque lake somewhere in central Idaho (Salmon basin) that has a natural trout population. By natural I mean not-introduced by humans at any point and not stocked; a population that arrived there by swimming up a headwater stream. So fish that arrived there prior to the 1800's. I am looking for such a lake for catch and release fly fishing. I know I can use the stocking records on your website to find lakes that don't exist in the database, but since those records only go back to the 60's and there was stocking before that in many areas it is difficult to know. I guess the only way to be certain would be a genetic analysis of the different populations. But does Idaho Fish and Game have any records of alpine lakes with pre-historic trout populations that have not received subsequent stocking? Maybe for Bull trout it's easier to assume they were present naturally, but what about westslope cutthroat? My sincere thanks for any help.
I hope you're not too disappointed, but there were never fish in the type of lakes you describe. Prior to the beginning of mountain lake stocking in Idaho, headwater barriers and subsurface flows prevented native fish species from reaching upper elevation mountain lakes. In the early 1900's enterprising sportsmen began transporting native salmonids (cutthroat and rainbow) and non-native brook trout to mountain lakes. Once established in the upper elevation lakes, the fish were transported downstream by surface flows.
In Idaho, there are hundreds of high elevation cirque lakes with no inlet or outlet and they are totally fed by snow-melt. A number of these lakes are not stocked with fish for various reasons - including extremely difficult access and protection of native amphibians.