Bullhead, a 15 acre pond is rather large when it comes to private ponds. You can have a lot of potential to do more than what you could do with just your typical 1 or 2 acre pond. So the ability to add a "little spice" to your pond is there...

As you stated in the first post, the pond is rather old, probably silted up and shallower than it was when built. The first thing you really need to do is make sure the dam is solid and not going to fail anytime soon. You would hate to put a lot of money and time into a pond to only have it all flood away!

Once you know the general structures of the pond are secure then you can go about managing from a more biological aspect. Find out just how deep it is... Whether that is by lower a rope with a weight on it, or using a portable fish finder and cruising around the pond. 15 acres is a big area to check by rope and weight! You may want to consider a portable fish finder such as this one: Portable Fish Finder Once you have used it to chart your pond's depths you can later use it to fish with!

Then you can start fishing the pond in a manor to see what you got and hopefully the NGPC will be able to assist you with electroshocking. Until you really know what kind of fish community you have, I would not add fish or remove fish. After the NGPC has assisted you then you can go from there.

Things such as adding new genetics to your pond, removing certain species that are too abundant and looking at other species to add a "little spice" to your pond.

Take some pictures of your pond and keep us updated. This sounds like quite the gem and a really interested project to work on...