The ponds were re stocked earlier this year, there are plenty of fish there.
The cormorants normally appear mid to late August, hit hard September - November then ponds usually freeze over for a couple of months then the pests come back before disappearing about March - April
The cormorants dont know the ponds have been restocked hence they have not turned up, as far as they are concerned there is no food in your ponds but they will find out and when they do your fish stocks will once again be depleted.
Half a dozen of these birds will eat about 50lbs of fish a week, thats several hundred 3-4oz fish, over 3 months thats a hell of a lot of fish.
I have seen first hand how these birds have reduced a quality fishery to a water devoid of almost any small silver fish, granted the water was not stocked but being a canal top up reservoir it used to hold tens of thousands of silver fish, the natural balance of fish stocks has been completely destroyed.
The problem with this particular water is that the reservoir is within a country park and the water birds are encouraged by the wardens including cormorants because "the public like to see them" the public dont see the damage the birds do because its under the water, what really annoys me is that the mink were trapped and eradicated very quickly but the cormorants have floating jetties built for them!!
Ian.