Torpedo ray tagged by Dalhousie University researchers

Researchers from Dalhousie University in Halifax are hoping technology will help them learn more about some underwater giants living off the East Coast.

This weekend the team planted a satellite tag on an Atlantic torpedo ray — a fish that can grow up to 250 kilograms and reach nearly two metres long.

What makes this ray somewhat unusual from its relatives is its powerful electric organs, visible as large, kidney-shaped patches on the side of its head that can put out a shock of about 200 volts.

"It uses that to stun prey, knock it out and then it swallows them whole," said Fred Whoriskey, executive director of Dalhousie's Ocean Tracking Network.

"Caution is advised [when dealing with] anything with that kind of an electrical shock. It would be probably more than sticking your hand into a 120-volt socket."

Unbeknownst to most people, they are in the waters off Nova Scotia.

"They're a rare species," said Whoriskey.

"They're cryptic to start with so we really don't have a good idea of how many of them are out there and we do know that they don't like the cold water all that much so they'll disappear after the summer. Where they go afterwards? Probably south but we don't know."

On Sunday, researchers with Dalhousie's Ocean Tracking Network placed a satellite tag on a torpedo ray near Ketch Harbour.

Whoriskey, executive producer of the OTN, performed the honours — but he was careful around the fish that could send such a powerful shock through his body.

In fact, other rays have turned on divers filming them. In one recent incident in Ketch Harbour, a diver had his camera attacked.

"We were prepared for them to take offence to having a tag put in their back," said Whoriskey.

"But in this particular case, it was disturbed by what we did and decided that we were not good company and left in a huff instead."

Whoriskey and Chris Harvey-Clark, Dalhousie University's Director of Animal Care, say implanting the tag in the fish means they will be able to get data on its activities for the rest of this calendar year.

"We know almost nothing about it. I mean anything that a Grade 3 class would ask you: how old do they get? Where do they go? Where do they reproduce? How many are there? We don't know anything about this animal," said Harvey-Clark.

"This satellite tag that we put on the animal on Sunday is basically going to tell us: where it goes, how deep it goes, the water temperature — for the next 3 months."

The tag will then release from the animal and pop up to the surface, sending a signal to an Argos data-collecting satellite which will receive data transmitted from the tag.

The data will offer a wealth of information about the creature's biology and could reveal some new information that could be used by ocean researchers.

"If we can understand how animals depend on certain temperature regimes we can predict where they are going to be in the future," said Whoriskey.

"The technology is letting us open up the mysterious world of these animals in ways that we've never been able to do before. So yes, from that perspective it is revolutionizing what we're doing."

If the satellite tag works the way it is designed, the information should land in Dalhousie's computers sometime in the new year.