So far, we have some threads. Jed Welsh nicely connects them for us :
In Scotland there was [a] series of lakes that the Scots simply named lake one, lake two, lake three, etc. The most popular lake was Lake number eleven. The Scottish lingo for the lake was “Loch Leven.” It was from this lake that the Scottish brown trout were planted in the Eastern Sierras. We didn't call it a brown trout we called it Loch Leven.By the way, there are different strains of brown trouts: red-and-brown-spotted German and the “real” Loch Leven trout—but neither one is native American .
Summary: North Sierra's Loch Leven Lakes are named after a European trout species nicknamed after a lake named after a number.
Keywords: geography, history, Scotland, Sierra Nevada, North America, toponym, brown trout, natural history, folklore, lingo.
References and more to explore
 J. L. Medeiros: A Naturalist's Transect along the I-80 Corridor in California: Rockin to Donner Pass [see Stop #7 in www.sierracollege.edu/ejournals/jscnhm/v2n1/fieldtrip2.html].
 Historic Scotland: LochLeven Castle [www.historic-scotland.gov.uk/propertyresults/propertyoverview.htm?PropID=PL_202].
 Salmo trutta Linnaeus, 1758 [http://nas.er.usgs.gov/queries/GreatLakes/SpeciesInfo.asp?NoCache=6%2F17%2F2010+1%3A38%3A11+PM&SpeciesID=931&State=&HUCNumber=DGreatLakes/].
 George van Zant: Jed Welsh - Brown Trout of the Eastern Sierra [www.bigfishtackle.com/fishing_articles/Featured_Fishing_Authors/George_Van_Zant/Jed_Welsh_-_Brown_Trout_of_the_Eastern_Sierra_338.html].
 Lenn Harris: Not All Brown Trout Are German! [www.ultimateoutdoorsradio.com/not-all-brown-trout-are-german-by-lenn-harris/fishing-reports/].