Mr Ross said concerns have arisen over reports that witnesses had seen a second baby whale being dragged down the beach by members of the public and heard it had later been shot.
DoC spokesman Darren Jones yesterday confirmed a juvenile whale had been euthanised without the department's knowledge.
He said DoC had recovered the body and an autopsy revealed the male baby was seriously ill and would have suffered a painful and lingering death without being euthanised.
However, he reminded members of the public finding sick or injured wildlife to contact DoC or Ministry of Fisheries staff and not take matters into their own hands.
DoC is responsible for the protection, conservation and management of marine mammals within New Zealand waters, regardless of whether the mammals are dead, beach-cast or stranded.
The female rescued at Glinks Gully was found later in the day stranded about one kilometre north of the Baylys Beach settlement. Seriously sick and not expected to live, she was euthanised.
Kauri Coast area manager Meirene Hardy-Birch said: "Euthanasia is a difficult decision made for the welfare of the animal."
Tests and photos confirmed it was the same adult whale which had been refloated at Glinks Gully.
It is hoped further tests will reveal why the whales stranded.
If you come across a stranded whale, call 0800 362 468 or 0800 DOC HOT.