Conservation Minister Eugenie Sage is calling for the public to send in any tips on the seal pups found beheaded in a bay on Banks Peninsula.
Six fur seal pups were found decapitated by a tourism operator on Monday, with the heads still missing.
It's been confirmed that they were 11 months old.
"I felt sick to the stomach when I heard about that," Ms Sage told RadioLIVE.
Ms Sage suggests that the slaying could be linked to unwarranted hostility that local fishers feel towards seals in the Banks Peninsula. "Some fishers may feel that the seals target the fish that they are after," Ms Sage said.
But she clarifies that the local fur seal diet is largely comprised of lanternfish, which is not what fishers are after.
It's also been speculated that the seal pups were subject to a shark attack, but DoC has since ruled it unlikely given the untouched state of the pups' bodies.
The Department of Conservation (DoC) urges fishers to respect catch sizes and limits and report illegal fishing - which will help ensure healthy fish populations for all. DoC spotted illegal fishing in the Pōhatu Marine Reserve near Akaroa last weekend.
It is a criminal offence to harass, disturb or harm fur seals, which are protected under the Marine Mammals Protection Act.
Illegal or suspicious behaviour should be reported to DoC at 0800 DOC HOT(0800 362 468).