The Conservation Minister has launched an investigation into the deaths of 15 fur seals on the Marlborough coast.
It is feared the seals have been deliberately killed, with some showing signs of being shot.
Conservation Minister Steve Chadwick said the deaths need to be explained, as it revoltspeople to know that someone may have gone out for blood sport.
South Marlborough area office manager Dave Hayes said he does not want to guess the motive behind the apparent killings but none of the seals have had their skins removed.
He said some of the mammals have broken skulls and holes in their skins that are consistent with bullet wounds.
"Some of them have been there for quite some time," Mr Hayes said.
He said locals found the carcasses while walking on the remote beach at Needle Point last week.
A total of 25 seals were counted in the area in September but the area is not a breeding ground.
He said anyone with information should call the Marlborough area office on 03 572 9100.
The punishment for killing or harming marine mammals includes up to six months in jail and fines of up to a quarter of a million dollars.
In July 2005, All Black Andrew Hore and two Otago farmers were convicted and fined $2500 each for killing a fur seal off the Otago coast.
Judge Peter Rollo described the crime as "grossly irresponsible, spontaneous act of hooliganism".
