The dead killer whale was found on Monday at Whatipu Beach, West Auckland.

An orca has washed up at Whatipu beach in West Auckland, possibly the victim of being hit by a boat.

The adult male whale was reported to the Department of Conservation on Monday, which then sought permission from local iwi to launch a post-mortem investigation.

Coastal-Marine Research Group Director Karen Stockin said photographs taken by Department of Conservation rangers showed possible blunt force trauma to the head.

Project Jonah New Zealand Teams will work to determine what killed the adult killer whale.

"At this stage it's too early to speculate what the cause of the trauma may be, although boat strike is an obvious consideration," Stockin said.

A team from Auckland's Massey University will examine the animal on Tuesday afternoon.

They aim to take a biological sampling of the animal to assess diet and pollution loads.

Orcas are considered "nationally critical" in New Zealand with known threats being fisheries interactions and boat strike.

Marine mammals in New Zealand are legally protected under the Marine Mammal Protection Act (1978).

Anyone who accidentally kills or injures a marine mammal is required to report the incident to a fishery officer or the Department of Conservation within 48 hours.

Under the Marine Mammal Protection Regulations (1992) vessels must avoid rapid changes in both speed and direction and not exceed speeds faster than the slowest mammal within 300 metres.

Vessels travelling at speeds over 15 knots are more likely to kill a whale or dolphin if they hit it and can still cause severe damage if travelling over five knots.