LOL.. the pic is way too large ... it would help if you posted it at say 800 pix wide ....
--
Regards
Cees (The Netherlands) http://members.home.nl/c.achterberg
Since your photo is near monographic anyway, I would convert the image to a powertone (easy in GIMP; duplicate the layer for a total of three layers, Set the top layer to Value, Center layer to Saturation, and replace the base layer with the fill Color of choice) to remove them. Maybe some sharpening (very subtle of course) would help too.