"They were approaching too fast and just driving her off her calf. It was a disgusting display of human behaviour."
The whale and dead 300kg calf were spotted on Saturday by a fisherman on the Hauraki Gulf and it was about 5pm the same day that Dr Visser managed to find them. She slept on her boat overnight and it was about 3pm on Sunday when boaties forced the orca to leave.
"In the time we followed her, she was only metres away from the calf that she was pushing ahead of her in the wind and current."
Once the mother had left, the calf was buried on a nearby island with the blessing of local iwi.
"The mother has been re-sighted moving very fast out of the area, but accompanied by the rest of her group, who had remained with her during the whole process," Dr Visser said yesterday.
She said with so many orca around Northland's coast as well as plenty of dolphins, boaties needed to be vigilant and careful around marine life.
"Boating season is here and people need to be aware of whales and dolphins and give them the space legally required."
If you see orca in New Zealand waters, please call 0800 SEE ORCA.
Approach marine life with caution
Rules around marine mammal encounters:
* Do not disturb, harass or make loud noises near marine mammals.
* Contact should be ceased should marine mammals show any signs of
becoming disturbed or alarmed.
* Do not feed or throw any rubbish near marine mammals.
* Avoid sudden or repeated changes in speed or direction of any vessel or
aircraft near a marine mammal.
* There should be no more than three vessels and/or aircraft within 300 metres
of any marine mammal.
* Ensure that you travel no faster than idle or "no wake" speed within 300
metres of any marine mammal.
* Approach whales and dolphins from behind and to the side.
* Do not circle them, obstruct their path or cut through any group.
* Keep at least 50 metres from whales (or 200 metres from any whale mother
and calf or calves).
Swimming with whales is not permitted.