An endangered orca is not letting go of her newborn calf, whose body she has been pushing through the water for more than two weeks.

The whale known as J35 was spotted in coastal waters near the border between British Columbia and Washington state Wednesday with the carcass of her calf that was born and died on July 24.

Sheila Thornton, a research scientist with Fisheries and Oceans Canada, said experts are becoming concerned that the whale’s behaviour will interfere with her ability to forage.

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No intervention is planned, she said, but they will monitor her condition.

“I certainly think the duration of carrying the calf is unprecedented,” she said during a conference call with reporters on Thursday.

“You can look at that as mourning behaviour, there are a lot of different theories out there. It’s very difficult to say, but certainly they’re very intelligent animals and the loss of this animal is quite profound for both the (killer whales) and I think for everyone who witnesses this.”

The carcass is “surprisingly intact,” she said.

Brad Hanson, a wildlife biologist with the National Oceanic and Atmospheric Association in the United States, said removing the calf, in order to encourage the whale to forage, is not an option.

“Obviously the connection they’ve formed with this calf is substantial and it’s something that we do have to take into account,” he said.

They spotted J35 while searching for another of the remaining 75 southern resident killer whales, labelled an endangered species in both Canada and the United States.

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Scientists on both sides of the border have been working together on an emergency rescue plan for a young female orca known as J50 that appears emaciated but continues to swim alongside her mother.

Foggy conditions and ocean swells have prevented the teams from collecting breath and fecal samples, which requires getting within five metres of the young orca while matching her pace.

The earliest the weather is forecasted to clear up is Sunday, Hanson said, and the plan will be easier if the whales move closer to the coast.

The experimental, emergency plan to save J50 requires scientists to nail down her ailments through breath and fecal samples, then administer long-lasting antibiotics by either pole-mounted syringe or dart. If that goes well, they say they will try feeding her Chinook salmon filled with other medication.

The plan hit a snag in Canada, which has taken longer to get licences in place than in the United States. But as of Wednesday night, Fisheries and Oceans Canada says it has received an application from NOAA to administer the antibiotics. The salmon-feeding plan is still under review.

“We are working closely with NOAA and are considering every possible option available to us to save this whale. Our decision will be evidence-based and we will act quickly together with our partners when the conditions are right to move ahead with any action,” the federal department said in a statement.

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“We are prepared to issue permits for the best course of action for this whale without delay.”