They can be seen at Colac Bay, Riverton Rocks and sometimes near Mitchell’s Bay.
Southland Surf School coach Jessica Terrill said she saw around five of the mammals at Colac Bay this summer.
“You often see them traveling in small groups.”
The dolphins were regular visitors but were more visible to the public during the summer season, she said.
“They love to surf with us and when you catch waves it’s almost like they’re racing you.”
Ms Terrill has been a surf coach for about 10 years in the area and said the numbers of dolphins seemed to be increasing slowly but steadily.
Colac Bay marine researcher Gemma McGrath said two types of dolphins regularly appear in Riverton and Colac Bay, Bottlenose Dolphins and Hector’s Dolphins.
Hector’s dolphins could be identified by their black round fin and size, as they were one of the smallest dolphins in the world.
They were originally from New Zealand and had a small range along the coastline of 30-50 km, which meant they generally stayed in their local area.
Hector’s dolphins in Colac Bay could be different individuals than the local ones in Riverton, Ms McGrath said.
She advised the public when around dolphins to behave responsibly.
“Give them their space but take advantage of it.
“They are really special, only found in Aotearoa and most of the time they are eager to interact.”
It was a privilege and an honor to be in the same space as the mammals, she said.
“They are quite gentle, curious and friendly.”
She had studied mammals for about 20 years and had researched Hector’s dolphins in the area for about three and a half years.
She had found Riverton articles dating back to 1922 during her research.
Dolphins were called porpoises until the 1980s, she said.
She hoped to see their numbers increase over the next few years.
“It’s a very slow and precious recovery rate, but we’ve seen calves every year and we’ve seen them grow into little dolphins. So if we could see more of them that would be great.”