The mother of a Southland woman attacked by a shark says she has a 'long recovery ahead'

Police are urging swimmers to be cautious, after the 21-year-old was bitten was bitten on the leg in Riverton in the early hours of yesterday morning.

She was was knee-deep in the estuary near the rugby grounds, and it's thought the culprit was a seven-gill shark.

Her mother says she's doing well post-surgery, and is in ICU at Southland Hospital.