Mr Foster was due to fly in at first light today and would be in the Bay by the afternoon.
Department of Conservation senior biodiversity ranger Brad Angus said the department had been monitoring an orca calf in the Bay of Plenty for a week.
"The best thing we can do for this young orca is to minimise interaction and direct contact with people as this will place more stress on the animal," Mr Angus said.
DOC is asking for the public to stay away from the orca as approaching it would only add to its stress.
Dr Visser also urged members of the public to stay away from the calf because it needed all its energy to survive.
"One of the reasons it can survive on its own is that it has a blubber layer. At the moment it's metabolising it's blubber supply," she said.
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Orcas were opportunistic feeders and it sometimes took them a day or two to move between feeding patches so they could survive for a while, she said.
Dr Visser said she was not sure if the youngster had been feeding at all since he was separated or if there was enough food in the area to sustain it.
"It's a growing youngster and the water's cold. It's warm blooded therefore it will feel the cold," she said.
"It's dire circumstances for the calf. It's dehydrated. It needs to use all of his energy to be able to survive. We are very concerned that if people start coming out in boats that it will have to use its energy to avoid the boats.
"We don't know how long it can sustain this."
Given its size it was likely the orca was not totally reliant on its mother's milk and was able to hunt at least well enough to supplement its food, she said.
Dr Visser said orca had been known to retrace their steps to find a lost calf and she was still hopeful they might return but as time went on it became less likely.
"Every day that goes past it's a bigger area to search. We don't know if the area it was found in is the area it was lost from."
How the orca has become separated from its pod would be pure speculation, Dr Visser said.
Mr Foster would assess the situation tomorrow afternoon and a plan would be formulated in conjunction with the DOC and iwi in the area, she said.
Call the DOC hotline on 0800 362 468 and Orca Research Trust on 0800 SEE ORCA if you see any orca pods in the Bay of Plenty.