New here and need advise ASAP!

Hello folks! I am usually on the Gardenweb forums in the birding sites or the pond forum. I am in forest land in West Michigan. I have a small 600 gal pond, there are 2 small ponds above with waterfalls leading to the 500 gal below. I have assorted Gold Fish from 10+ years old to babies from last year. I am pretty heavy on fish load. I am a 5 minute walk to a nice lake with a marsh in between. I had noticed a real decline in my frog population over the past few years, infact I have not had tadpoles in 4 years.
This year I have more frogs than ever (I see 20 at a time and I have lots of plants), most are Green Frogs around 1" to 2" and a few around 3". I have had frogs overwinter in the 500 gal pond safely and a few that tried to overwinter in the 2- 50 gal pond that died. I am afraid if I get to many frogs trying to overwinter it will increase the load on the pond and I will lose both fish and frogs over the long frozen months. I would like to know if I should gather up the majority of the frogs and take them to the marsh. I know a lot will leave on thier own but my taking them will insure the make it there safely. Is this a good idea? If so when? I would love for them to stay as long as is safe. Thanks!