Or you could take a chainsaw and cut the appropriate nest sized sized hole in the ice, pushing the block of ice that you cut under the existing pond ice. That would allow you to drop the rocks in position while standing on the ice. (depending on the ice thickness of course)

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3/4 to 1 1/4 ac pond LMB, SMB, PS, BG, RES, CC, YP, Bardello BG, (RBT & Blue Tilapia - seasonal).