The deaths of two Hector's Dolphins have reignited calls for a ban on set-netting in their habitats.

A young calf has died at Wakefield Quay in Nelson, while an adult died at Richmond Bay in the Marlborough Sounds.

It's prompted concern about a lack of protection for the animals in the Tasman Bay area.

Sea Shepherd's Tracy Brown says set-netting poses a danger to the survival of the species.

"New Zealand's stance as a proactive, environmentally conscious country should be doing their utmost to set good global standards for stopping the rapid decline of extinctions that are happening around the world."