Concern is growing for six dolphins stranded in a shallow waterway in northern New Brunswick after a second attempt to rescue them was unsuccessful.

It has been a week since seven dolphins became stranded near Lameque and one has since died.

While the six remaining Atlantic white-sided dolphins – two of which are young calves – appear to be healthy, Andrew Reid of the Marine Animal Response Society says time and food supply are becoming issues.

"There is a risk these animals could become dependent on people feeding them,” says Reid. “At this time we definitely don't want to offer any encouragement for them to want to stay in that area. At this point it is still better not to feed them.”

Reid says the dolphins have drawn a lot of attention from area residents, but he is urging people to keep their distance and let Fisheries and Oceans handle it.

To escape, the dolphins would have to swim through an area that's only about a metre deep at high tide, and dolphins don't like shallow water.

Rescuers say it was a challenge to keep the pod moving without stressing them too much.

“There's a few tail slaps, some vocalizations we could hear. So it was bugging them, but it's part of the process to try and herd them. You have to convince them to go where they don't want to,” said Reid.

An attempt was made last week to herd the dolphins back into open water but it was unsuccessful.

A second attempt was made Wednesday morning as rescue crews in three boats tried using the sound of metal rods to move the dolphins out of the basin and toward open water. However, the animals kept swimming around the boats and back to the basin.

The operation was called off after an hour and crews say they’re now considering more aggressive options for their next attempt, including beaching the whales and using stretchers to bring them back to open water.

“We realized the dolphins seem to be happy in that pool of water underneath the bridge,” said fisheries officer Gabriel Albert.

The groups haven't ruled out using aquatic pingers, which are used to scare dolphins away from a certain area, but they are still being shipped from Cape Cod.

Crews say tides are also making the rescue attempts difficult. Ideally, the pod would be moved during high tide in the early morning or late at night when visibility is poor.

The group is trying to bring aquatic pingers in from the United States to scare the dolphins through the passage but they haven’t arrived yet.

"Unfortunately they were initially turned back from the border and sent back to the Cape Cod Stranding Network,” says Reid. “They are sending them again but that is going to delay things."

The crews haven't decided when they'll make their next attempt, but can only hope the third time will be the charm.

Atlantic white-sided dolphins are common in Atlantic Canada. They can reach 10 feet in length and 500 pounds.

With files from CTV Atlantic's Cami Kepke and The Canadian Press