A pod of ten orca, including two young calves, were spotted in Akaroa Harbour yesterday afternoon - the first reported sighting of orca off the coast of the South Island this year.
Black Cat Cruises said more than 80 passengers aboard the Akaroa Harbour Nature Cruise rushed for their cameras, after skipper Julian Yates sighted the pod near the Akaroa Lighthouse.
Mr Yates said the pod included one alpha male, a second male with a damaged dorsal fin, four females, two juveniles and two calves that were approximately one or two-years-old.
Dorsal fins provide stability to orca when swimming - but Mr Yates said the male didn't seem to be affected by it's damaged fin.
"The younger orca were curiously approaching and hanging around our cruise boat while the males stayed distant and led the pod into Daemons Bay," he said.
Staff determined the sex of orca by analysing the mammal's physical characteristics.
Males typically grow between seven and eight metres long and weigh up to 5.5 tonnes whereas females are smaller reaching approximately six metres in length and up to 3.6 tonnes in weight. Males also have a distinctive dorsal fin up to 1.8 metres tall. The fin of females is shorter and more curved.