Environmental group World Wildlife Fund (WWF) is attempting to have snubfin dolphins listed as a threatened species.
The group says the listing would make it harder for companies such as Inpex to go ahead with developments that affect dolphin habitats.
The Northern Territory Government yesterday recommended a proposal by Japanese consortium Inpex for a gas plant in Darwin Harbour be approved, subject to some conditions.
WWF campaigner Lydia Gibson says several areas near the dolphins' habitats are being earmarked for development.
"What we're finding is that wherever this species is, there is significant threat from large coastal development," she said.
"It is absolutely paramount that we get the legal protection in place to start recovery actions to make sure these populations are protected into the future."
Ms Gibson says there are large coastal development proposals in the Territory, Western Australia and Queensland that could affect snubfin dolphins.
She says listing the dolphins as threatened could take up to a year.
Inpex has already said it will try to avoid blasting in Darwin Harbour during the construction of its planned $12 billion gas plant.
It says it will blast only as a last resort.
A report by the NT Environment Department says if the company does decide to blast, it must undertake further research to see how it would affect harbour dolphins.
But Stuart Blanch from the Northern Territory Environment Centre says that is not good enough.
"I would be interested to know how they are planning to manage dolphins that are floating in the harbour if they got blown up or killed or maimed from blasting, after it has happened," he said.
"It is very simple: you prevent them from blasting and be very clear, up front."