"That shows the real value of marine reserves. Having a humpback whale, only the second in memory in the harbour, coming in to feed there is a great example of how successful marine reserves are," she said.
They spent about two hours watching the whale, which gave a number of people on the water and on shore a spectacular view, but some boaties earned Dr Visser's ire.
"The vast majority of people were cool and respectful, but there were two idiot boaties out there. One drove at the whale at full speed, forcing it to veer off at a 90 degree angle, while another sped over the top of it as it was diving," Dr Visser said.
"But the thing is, those that just stayed in the water had a much better experience as the whale was very curious and kept coming up to boats that were just staying where they were. When it went near Smugglers Cove there were some people on the rocks fishing who got a great view, but when people were being idiots in their boats it would go away."
Under the Marine Mammals Protection Act, breaking the rules around marine mammals can lead to a maximum penalty of up to two years' jail or a $100,000 fine.
Anybody who sees orca or any whale off the Northland coast can contact Dr Visser on 0800 SEE ORCA.