This may help answer the question, from the DEC website...
"...In 2008, the DEC purchased an automated fish marking trailer (AutoFish) capable of adipose clipping and/or applying coded wire tags (CWTs) to salmon and trout automatically at a high rate of speed and accuracy. From 2008-2011, DEC and the Ontario Ministry of Natural
Resources and Forestry “mass-marked” all stocked Chinook salmon with an adipose fin clip in Lake Ontario to determine the relative contributions of wild and hatchery stocked Chinook salmon to the fishery. To evaluate the relative performance of pen-reared and traditional, shore-stocked Chinook salmon, DEC marked sub-samples of Chinooks stocked at pen-rearing sites with CWTs in 2010, 2011, and 2013"
Also regarding wild fish...
"Percentages of wild Chinook salmon in Lake Ontario varied by year class and age and among regions from 2009-2014, but overall, wild Chinook were an important component of the Lake Ontario fishery averaging 47% of the age 2 and 3 lake harvest.
Returns of Chinook salmon at the Salmon River Hatchery from the 2008-2010 year classes suggest a high degree of homing by fish stocked at the Salmon River and a low degree of straying from other stocking sites, with estimated average straying rates of 12.4%, 8.4%, and 10.9%, respectively.
Hope this helps.