A New Zealand sea lion and a leopard seal have been "gunned down and left on the beach to rot" in two separate incidents on the Southland coast in the past week.
The deaths have shocked Department of Conservation staff and they would like to hear from anyone who could help identify those responsible.
Doc Southland biodiversity programme manager Jessyca Bernard said to find a sea lion at Waipapa Point and then a leopard seal at Waikawa Harbour only a few days later that had been killed in the same way defied explanation.
"It makes no sense why these animals were gunned down and left on the beach to rot. It's mindless behaviour."
The sea lion population is declining and leopard seals are rarely seen along the Southland coast as they prefer the Antarctic or subantartic.
Both animals were sub-adults about 2m long and in good condition in every other way, she said.
Doc staff had retrieved the bullets from both animals and hoped people would come forward with any information they had.
One caller confirmed the leopard seal had been alive and playing at 10am on Sunday only to be found dead later that day, Ms Bernard said.
"They're magic to watch and they really don't deserve to be shot for absolutely no reason."
The New Zealand sea lion is one of the world's rarest sea lion species and fully protected under the Marine Mammal Protection Act 1978.
Offences under the Act carry penalties including fines up to $250,000 or a prison sentence of six months.
