Heron visiting my pond

I thought this might happen sooner or later, given my rural location. My son photographed a blue heron scoping out my pond a couple of days ago. I posted three pictures at http://tinyurl.com/5vtng. Look at the last three photos, named Heron1,2 & 3.

The question now is what can I do to discourage the heron and still keep fish and maintain the esthetics of my pond. It looks like my 4 koi have stayed deep enough to stay out of his reach, so far. I have laid some chicken wire fencing over part of the pond for now but need a permanent solution. Should I put up a low electric fence so that he gets shocked when he approaches the edge?

I suspect he will keep returning, now that he knows the fish are there.

Scott M.
Ottawa, Ontario