Whale researchers spent another day at the Old Port of Montreal Monday trailing a young beluga whale that has swam upstream.

First spotted in the port three weeks ago, the marine mammal is some 500 kilometres southwest of its natural habitat in the saltwater seas of the Gulf of the Saint-Lawrence in the Tadoussac area.

Hopeful whale watchers have been visiting the Old Port for days in hopes of catching the rare site. The wayward whale has been spotted several times swimming under the Jacques Cartier Bridge.

“He comes to the surface for about four or five breaths, then he dives for anywhere between four, five, six or seven minutes, said whale researcher Robert Michaud.

Michaud and his team have been hoping to observe the beluga up close, but are somewhat baffled by its behavior.

While the animal is swimming quickly and doesn’t appear weak, it is rather thin, and it seems to have developed wrinkled skin.

“It's a marine animal; it's supposed to be in salt water. In fresh water, he develops skin problems,” said Michaud.

The researchers are using a dart gun to take skin samples, to see if the beluga has a serious infection, because there are concerns the beluga’s skin condition is deteriorating.

Another concern is the beluga’s safety in the port. Extremely social creatures, when belugas aren’t with a pod of other whales, they tend to approach boats and can be seriously injured by propellers.

“It's a small population; it's endangered,” said marine biologist Pierre Beland. “It may be shrinking in size so we're worried about maybe losing another animal.”

Researchers and whale lovers hope the animal will return home on its own.

"We're hoping this animal’s instinct will kick in and it does feel this call, this need, to migrate and will head back out to its natural habitat in the estuary in the Gulf of St. Lawrence,” said volunteer whale watcher Gwenneth MacMillan.

If not, researchers say they will decide on a way to move the animal downstream, and return it to the safer waters of the estuary.