Todd,

           When I went to Vermilion 4 years ago, there was a hardback book in our cabin that revealed results of studies on fish native to MN. What we found revealing (not having done my own research on the esox specifically) was the incredible growth rate of pike, but especially musky. As I recall, they stated something like 12" in the first year, up to 30" lengths in the first 4 to 5 years. Most of this growth would be expected during the warm water months as a fish's metabolism speeds up. Girth is another subject entirely. The book stated that as the fish's biological energies are turned away from growing length in the formidable years then the energy becomes more manifest in adding girth through the rest of the life cycle. I'm assuming that's why you can catch a nice length fish in newly stocked waters but rarely see tremendous girth until the  population becomes more mature. Just some rambling thoughts.