Ladyann skipper Karl Maley and deckhand Jess Ngawhika were anchored at Hayes Gap, about 300m offshore from the Nuggets, on Monday, when they became held fast.
''I'd been dragging the anchor all night as it was quite a windy night. But in the morning I couldn't get it back up,'' Mr Maley said yesterday.
''I had a few goes at it and was going to leave it behind, but decided to give it one more go.''
On the fourth attempt, the anchor did come up - but with another anchor attached.
''It looks like it's been down there for a long time. It's off a smaller vessel, something like a brig, by the look of it,'' Mr Maley said.
''It took us about an hour to get it up. It did a bit of damage to the boat getting it on board. The boat keeled right over. It took four of us to lift it off the boat back at the wharf.''
He estimated the barnacle-encrusted iron anchor weighed about 250kg and said it was ''definitely'' the most unusual catch he had brought up in 21 years of fishing.
''I was quite pleased. I'm hoping to put it in the garden. Although, I wouldn't mind finding out a bit of the history about it.''
The anchor looks similar to one displayed in the Owaka Museum from the first recorded wreck in the Catlins; the 90-ton schooner Henry Freeling on the Tautuku peninsula, on November 12, 1839.
However, the latest discovery was a mystery to former shipwreck diver Michael Brown, of Balclutha, who donated the Henry Freeling anchor to the museum 20 years ago.
''I've never heard of any shipwrecks in the area where it was found. But who knows how it could have ended up there,'' Mr Brown said yesterday.
Wrecks listed by Shipwrecks New Zealand near the mouth of the Clutha River are Endeavour (1857), Ada, Pioneer and Ann Jane (1861), South Australia (1867), Taiaroa (1871), Mary Van Every and Tuapeka (1874), Lady of the Lake (1875), Lloyd's Herald (1878) and Margaret Casey (1904).
