However, the main source of damage to swans and cygnets is poisoning caused by lead weights discarded, or lost, by fishermen.
The figures for the past three years are: 3,000 cygnets and 6,000 older birds.
The symptoms of lead poisoning are seen not only in the white swans over one year old but in the cygnets of only a few weeks.
The cygnet has a light grey plumage with black bill and feet.
Selected wild cygnets had their wings clipped and bills cut into a distinctive pattern bearing the owner's mark.
The cygnet is a patchy color, with brown and gray hues.
The cygnets hatch after about 36 days and have a grey or brown plumage.
