Dwight,
If you wait until late this fall to stock, a good portion would survive predation. Also I would consider removing some small to medium sized LMB this summer and next to make room for the new guys.
You may also want to consider removing the big northerns that you catch and starting over again with smaller ones. I like to remove the muskies and notherns from the ponds I manage once they reach 28 inches or so. They are very beneficial fish up to that size, but they are not quite so beneficial when they get BIG.
Nate
