Lake trout in Jackson Lake take about 10 years on average to reach 20", around 2lbs. The G & F stopped stocking in 2005 or 2006. This means that any fish that would have been stocked past 2005 would be only 15" or so at the very biggest.
Are you complaining about not catching fish less than 15"?
There are very few lakes stocked with lake trout these days. They have done TOO well and we end up with lakes full of skinny 20" lake trout even without stocking....