The juveniles played behind the adults, and when up to 15 boats went out over the Whanganui River bar, the inquisitive orcas circled two of them, Mr Parker said.
"We thought they were coming into the mouth and upriver," he said.
Originally from Greymouth, and a former worker with Wanganui Trawlers for 11 years, Mr Parker said he had never before seen orcas, in Wanganui or the South Island.
DoC's Whanganui area office biodiversity programme manager Jim Campbell watched the orcas from South Beach.
He said the two pods which were visible off the Wanganui coast yesterday morning were probably one group, with between 10 and 16 to 18 individuals.
"Though it was hard to know with them popping up and down," Mr Campbell said.
"There was a pod of females and really young calves and the second had juveniles with some large males in there."
Orcas are regular visitors to the region and are probably part of a population that travels along the West Coast of the North Island.
"They were feeding moving down the coast. They were possibly eating sting ray, though it's hard to say," he said.
"It's one of the bigger pods we have seen. There were a lot of really young calves."
Mr Campbell said if anyone had photos of the orcas DoC would appreciate copies to help identify individuals in the group. The number to call is 349 2100.