I'm not in your area but a heron is a good bet.
They are year round residents in coastal states.
They are live here, in SE WA, all year.

Suggestions for fishing and wading birds
are

~ electric fencing, both the fido fence or the
over the pond version, check on Froogle.com.
~ motion activated sprinklers
~ bird netting
~ stringing fishing line around the pond area

ALL these methods work
(a pre-emptive strike for the prosaic post that netting and only
netting works... believe us, other methods work...)
The trick to each method is how your particular pond and yard are laid
out, and the particular bird who is fishing in your pond.

In my blog, in the April archives, I have an article on the blue heron.

Sorry about your fish!

kathy :-)
www.blogfromthebog.com
new this week ~ turtles