Or multiple fish dropped by eagles?
waterfowl transportation of larva spiny ray fry has been suggested as one method of introduction to nearby watershed the idea being they may be able to survive on the wet feathers.
best info I can find on Fraser Watershed.
The first recorded occurrence of smallmouth bass in the South Thompson River watershed was in Phillips Lake in 1999 (Steve Maricle,BC MOE Regional Biologist, pers. comm.; Ken Tsumura, pers. comm., cited in Hatfield and Pollard 2006). However, no local or downstream captures have since been recorded for this waterbody, suggesting a failed introduction or erroneous species identification (Steve Maricle,BC MOE Regional Biologist, pers. comm.). Smallmouth bass have been recently confirmed in Gardom Lake, where a gravel outlet filter was constructed by the BC MOE in 2007 to prevent downstream movement of spiny-rayed fish species during seasonal outflows (Steve Maricle,BC MOE Regional Biologist, pers. comm.).
Following an angler-reported occurrence of smallmouth bass in July 2006, BC MOE staff confirmed this species to be present in four mainstem lakes and the mainstem channel of Beaver Creek, a tributary of the Quesnel River north of Williams Lake, BC (see Table 35 and Figure 9). Based on the lack of historic stocking of bass species by government agencies in the middle Fraser River watershed and the geographic isolation of these confirmed occurrences from other known smallmouth bass populations in BC, it seems certain that they were established through one or more local, unauthorized introductions (Tom Wilkinson, BC MOE Regional Biologist, pers. comm.).
Smallmouth bass presence was confirmed for 50 waterbodies on Vancouver and the Gulf Islands, including 36 lakes and 14 streams (see Table 18). Unconfirmed occurrences for smallmouth bass were recorded for three additional lakes. Based on provincial watershed coding, confirmed and unconfirmed occurrence records for this species are distributed across 20 separate drainages, linked only by marine or estuarine waters.
First observation dates for Salmon River and Kawkawa Lake smallmouth bass are relatively recent, in 2000 and 2003, respectively (Tracy Cone, DFO Area, pers. comm.; Justin Peterson, Angler, pers. comm., cited in Hatfield and Pollard 2006). Neither population originated through authorized stocking activities (Erin Stoddard, BC MOE Regional Biologist, pers. comm.). This, together with the lack of direct physical connectivity between these waterbodies, suggests that their smallmouth bass populations originated through independent unauthorized introductions. Only a single capture of smallmouth bass has been reported for Kawkawa Lake, this individual weighing approximately 1.4 kg (Erin Stoddard, BC MOE Regional Biologist, pers. comm.). The lack of subsequent captures in this system may indicate a failed introduction attempt (Erin Stoddard, BC MOE Regional Biologist, pers. comm.).
https://waves-vagues.dfo-mpo.gc.ca/Library/337851.pdfA Review of Yellow Perch (Perca Flavascens), Smallmouth Bass (Micropterus Dolomieu), Largemouth Bass (Micropterus Salmoides), Pumpkinseed (Lepomis Gibbosus), Walleye (Sander Vitreus) and Northern Pike (Esox Lucius) Distributions in British Columbia. 2009
FWIW I heard the Kawkawa report which was of a large dead female is now regarded as a hoax. I have heard of LMBs in Salmon but not SMBs. Either way it's though the illegal introduction was thought to have failed.