bassman,
How big is your pond? How much fishing pressure does it receive?
(If your pond is small and receives a lot of fishing pressure, then you may have "hook shy" fish that will be difficult to sample by angling.)
Yes, the fish experts above have given you "better" ways to evaluate your dad's pond.
However, getting a big group of buddies together to "sample" the pond by fishing will be the most fun method of evaluation!
A dad with little kids might use small hooks and worms and get a good sample of your panfish. Some hardcore bass fisherman may work several different methods to sample your bass population. Then you might need some catfish people to specifically angle for those fish, because the cats can have a significant impact on your fish population, but not be sampled without specific targeting.
I personally like your "fishing derby" idea. However, if that doesn't work you can move onto seining or pay for a shock survey. Seining is not rocket science, but there are some experienced people on the forum that are capable of doing a 1000% better job at it than I could - so experience does make a difference.
(I did volunteer to help out some people on the forum on one of their seining jobs. I provided some free labor, and in return I learned about seining and met some really good people!)