Concern has been raised about coral bleaching in waters off the Northern Territory.

Rangers at the Garig Gunak Barlu National Park on the remote peninsula, about 60km north-east of Darwin, have filmed large patches of bleached coral from the air, in an area that showed only healthy coral three years ago.

“There's evidence that we've recently had a sea surface temperature warming event that is like a heatwave underwater,” Adele Pedder from the Australian Marine Conservation Society has told reporters.

Ms Pedder many of the Territory’s remote reefs have never been explored and studied.

“We know that climate change is having an impact, so we can expect more of these events, we can expect more coral bleaching happening in the NT,” she said.

The Australian Marine Conservation Society wants the NT and Federal governments to improve coastal management to reduce other stresses on reefs.

Ms Pedder says reducing these stresses would make reefs more able to recover from climate change-related bleaching.

“We know we need to keep our rivers clean, and flowing to the sea, we need to ensure that we don't roll out seabed mining in the NT,” she said.

“And we need to implement protections like Indigenous Protected Areas, jointly managed national parks, and recreational fishing zones, so we can maintain our fishing lifestyle.”