Ms Judd said humpbacks were fairly common around New Zealand at this time of year. They begin heading north after spending the summer feeding in Antarctic waters.
She said DoC would like to hear of any whale sightings off the Whanganui coast, including any photos taken.
"Whale movements are not that easy to monitor; and there are some whale species that are still a bit of a mystery."
For humpbacks, photos of their tail flukes are ideal. Each whale has a different black and white pattern on its tail fluke, so individuals can be identified.
However, Ms Judd urged people to be cautious about getting too close to whales to photograph them.
"We'd love people to report whales to us, but would hate for them to harm or injure any whales."
-Whale sightings can be reported to 0800 362 468.