Searchers have found debris today after two friends went missing at sea on Wednesday.

Whetuki Sam Kopua, 77, known as Sam, and Matekino Lucy Burling, 60, known as Lou, from Owaka, were reported missing on Wednesday after going fishing off the Catlins in south Otago.

Senior Constable Murray Hewitson of Owaka Police said the seas were too rough for an immediate search so people were combing the coast for clues today.

"We've found some flotsam from the missing boat."

Mr Hewitson said it was too early to say what happened to the boat. About 60 people were involved in the search.

"The boat's gone down and...after that we can't really determine what's happened."

He said search and rescue groups from across south Otago and Dunedin were involved and local boaties were helping search for the pair as well.

The Coastguard might join the operation tomorrow.

Mr Kopua and Mrs Burling were experienced sea-goers. Mr Kopua's wife reported the pair missing.