This 2012 document covers all of zone 5, which includes Quetico:
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Page 122 details Lake Whitefish distribution.

The sixth post of this thread(by oldgreygoose) refers to what may be the same information you have:
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Quetico Provincial Park Fisheries Stewardship Plan data from Brian Jackson, an MNR Biologist, and Lisa Solomon, Quetico Park biologist.
Alas, the link no longer works.  The post was from 2011, so perhaps we need to look around that time frame for park fisheries data.