The Merman of Orford

Is it possible that the Great Silkie of Sule Skerrie is not merely a legend? Is it silkies that the following historic documents are describing?

The earliest sighting of a silkie, at Orford in Suffolk, England, was reported by the chronicler Ralph of Coggeshall in his Chronicum Anglicanum of 1207. He tells how fishermen caught a wild man in their nets off the coast of Suffolk, and showed him to their lord, Sir Bartholomew de Glanville, Constable of the castle of Orford during the reign of Henry II:
‘He was naked and was like a man in all his members. He was covered in hair and had a long shaggy beard. The knight kept him in custody many days and nights, lest he should return to the sea. He eagerly ate whatever was brought to him, whether raw or cooked, but the raw he pressed between his hands until all the juice was expelled. Whether he would not or could not, he did not talk, although oft times hung up by his feet and harshly tortured. Brought into the church, he showed no signs of reverence or belief…. He sought his bed at sunset and always remained there until sunrise.
‘It happened that once they brought him to the harbour and suffered him to go into the sea, strongly guarding him with three lines of nets; but he dived under the nets out into the deep sea, and came up again and again as if in derision of the spectators on the shore. After thus playing about for a long while, he came back of his own free will. But later on, being negligently guarded, he secretly fled back to the sea and was never afterward seen.’

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