Biologists are warning a planned liquid natural gas terminal in eastern Quebec will endanger the region's fragile beluga whale population unless strict rules are imposed.

The $700-million liquid natural gas terminal near Cacouna, east of Rivière-du-Loup, was approved by the Quebec government earlier this summer.

Marine specialists are concerned about the terminal's port location in the middle of the belugas' birthing waters, where about one-third of the St. Lawrence female whale population gathers every year from mid-June to September to nurse newborn calves.

The underwater construction work needed to build the port will create a high level of water-borne noise that will aggravate the beluga population and may drive it away, said Véronique de la Chenelière, a biologist with the Group for Research and Education on Marine Animals (GREMM).

"The noise levels for this type of construction work in the water are well-documented, and they're loud enough to be very disturbing to those animals who base their whole life on sound," she told CBC News.

"It could cause the females and young to have to leave the area."

Biologists are not sure whether the pregnant whales can use other parts of the seaway to take care of their offspring, de la Chenelière said.

"Because they return to this area all the time, we don't know if they can go safely to any other place."

The belugas, which were declared an endangered species in 1983, are very vulnerable to any changes in their environment, she said.

"It's a threatened population and they have signs that this population is not increasing and has not been increasing for the last 20 years. We can't afford to lose any young."

The belugas' status has been downgraded to a threatened species, according to the Committee on the Status of Endangered Wildlife in Canada.

GREMM has asked the project's promoter, Énergie Cacouna, to ban underwater construction work during the calving season.

The consortium hasn't said whether it would be able to comply with the request, said TransCanada spokeswoman Kiersten Tucker.

"We are currently working with the Department of Fisheries and Oceans and specialists to determine when it would be required to stop construction, so we're currently evaluating that," she said on Wednesday. 

Beluga whales are part of the arctic and subarctic species of cetacean or large marine animals. The St. Lawrence population stands at around 1,000. Belugas normally reach a maximum of five metres.