A $5000 reward is being offered for information about the shooting deaths of two endangered sea lions in the Catlins this year.
Conservation group Sea Shepherd said the area might have a serial wildlife killer, after the body of an endangered male New Zealand sea lion was found shot on Tautuku Beach this week.
In April this year another male sea lion was found dead at Jacks Bay, also in the Catlins.
Sea Shepherd spokesperson Grant Meikle said the organisation was offering $5000 for information leading to the prosecution of the killer or killers.
It is illegal to injure or kill sea lions, and anybody caught doing so could face up to five years in prison and a $250,000 fine.