Video and photographs of orcas in Central Hawke's Bay waters, taken when orcas hunted dolphins last month, will be studied by orca expert Dr Ingrid Visser to see if they are New Zealand-based or foreign orcas.
Floppy Halliday of Whale Rescue said the pictures supplied by Hawke's Bay Today readers were helpful and would be studied by Dr Visser on her return from overseas.
"Hopefully, Ingrid will get some ID from them in time to come," she said.
David Petersen was in his Blackhead Beach bach when he saw hundreds of common dolphins "going absolutely ape".
"They were jumping two or three metres out of the water and going like anything," he said.
"We see a lot of dolphins out here and I've never seen dolphins go at that speed before - they were absolutely rocketing.
"Then we realised there was an orca, right inshore just outside the breakers, chasing them."
The dolphins sought refuge in the shallow waters of the beach and a nearby reef.
The pod continued north to Aramoana Beach but soon word spread the dolphins had returned - most likely responding to the calls of a mother and her calf stranded on the reef in the outgoing tide, Mr Petersen said.
Department of Conservation ranger Rod Hansen said locals quickly saved the mother and 1m calf, stranded directly opposite Wazmacs Camp.
"It was really good - all the locals just got together, rolled up their sleeves and got into it," he said.
Using beach towels as a sling, the dolphins were moved from the shallow water to the sea, with the calf moved first.
The mother called to it constantly, keeping it close to the reef, Mr Hansen said.
"She was bleeding slightly from damage on the reef. I don't think it was anything that was going to harm her."
Ms Halliday said the rescue effort was "fantastic work".
There was no record of New Zealand-based orca eating dolphins but orcas visiting from other parts of the world had, she said.