LAMEQUE, N.B. -- Animal rescue crews are hoping to use "acoustic pingers" to herd six stranded dolphins out of a shallow waterway in northern New Brunswick, and back into open ocean.

Andrew Reid of the Marine Animal Response Society says seven dolphins became stranded near Lameque last Wednesday, but one died two days later.

He said two of the six remaining Atlantic white-sided dolphins are young calves.

Reid said it's unclear why the dolphins got themselves stranded.

"They could have been chasing fish. They could have gotten into the main harbour and gotten confused. If you look at it on a map it's a fairly complicated area with numerous sandbars, so it could have been an incident of navigational error," he said Monday.

To escape, the dolphins would have to swim through an area that's only about a metre deep at high tide. So far, crews from Fisheries and Oceans haven't been able to get the dolphins to go through.

"These dolphins really don't like shallow waters, so they were herding them with some initial success, but then the dolphins started to evade the boats and went straight back to the deep pool by Lameque."

Reid said officials are now hoping to get some acoustic pingers to prompt the dolphins towards the exit.

"These devices were designed to scare away dolphins from gill nets. We're trying to get these pingers transported here. At that point we'll try herding the animals again -- hopefully with a better success," he said.

The pingers will be hung over the side of boats, and then those boats will slowly try to direct the dolphins towards the passage.

Reid said there are striped bass in the waters where the dolphins are stranded, but they may be too big for the dolphins to eat. He said if there aren't smaller fish for the dolphins to consume, that will become an issue as time goes on.

He said they may have to physically remove the dolphins, but are trying to avoid that.

Reid said the mass stranding has drawn a lot of attention from area residents, but urges people to keep their distance and let Fisheries and Oceans handle it.

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

-- By Kevin Bissett in Fredericton.