Blenheim police have arrested two men over the killing of seals on the Kaikoura coast last December.
Twenty-three seals, including eight new-born pups, were clubbed to death at the Ohau Point colony.
Two Marlborough men, aged 35 and 19, have been arrested and charged with aggravated cruelty to animals and possession of an offensive weapon.
They have been bailed to appear in the Blenheim District Court on Monday.
Police say the arrests follow an investigation in Kaikoura, Christchurch and Blenheim.
The Department of Conservation says it will probably take its own prosecution.
South Marlborough area manager Dave Hayes says the case will be followed closely and a prosecution under the Marine Mammals Act may be brought later.