Best thing to do is either contact the wardens at Rock Hall (at Crompton Way) on 01204 334343 or the RSPB on 08705 555999 and they should be able to assist you, or rather the Swan!
Today whilst at moses gate I noticed that one of the adult breeding swans on the back lake had got fishing line caught around its beak and was struggling to get it off. It needs someone to go up with a swan hook to help catch the bird and release the line. I hope there is someone out there that can organise this.