Everything I have read says you can leave your GC in your pond up to 5 to 7 years before they become pretty much non procutive. And you said it's only been 2 years so unless you just want to get rid of them because of how big they are you should still have a few good years left in the ones you have!

The only difference between a rut and a Grave is the depth. So get up get out of that rut and get moving!! Time to work!!