The Department of Conservation (DOC) is investigating after finding a dead sealion with gunshot injuries on a beach in the Catlins.
The injured animal was believed to have clambered ashore at Jacks Bay to lie in the sand dunes but later died.
DOC's acting operations manager for Murihiku Chris Bowen says the sealion died from serious blood loss and it would have been a "slow, painful death".
Mr Bowen says DOC is grateful to the public for reporting the animal.
"The shooting of an endangered animal is hard to comprehend. There are only about 10,000 New Zealand sea lions left so losing one in this way is particularly tragic."
DOC is leading an investigation and police have been alerted.
Killing or injuring sealions can lead to up to seven years behind bars or a $250,000 fine.
Anyone who may have information about this incident should contact the Murihiku/Invercargill DOC office on 03 2112400, the DOC hotline 0800 362 468.