Kaipara Maori are outraged after teeth were hacked from a large whale washed up on Ripiro Beach.
The 5m-long whale had washed ashore about 2km north of Baylys Beach about 10am on Friday.
Beachgoers saw two men using a tomahawk and pliers to extract teeth from the mammal, believed tobe a sperm whale.
Omamari Beachcare Trust spokeswoman Veronica Patuawa said whoever took the teeth was probably looking to make money and "knew nothing about Maori protocol" or respecting the dead whale.
Iwi vowed to "stand guard with baseball bats if we have to" until the Department of Conservation had visited the site and cleared the animal for disposal.
Then, in accordance with usual iwi practice, the jawbone was removed to be kept at a local marae and the remains buried on the beach.
Iwi representatives spent time talking to children milling round the area about whale strandings and the Maori legend of the sea god Tangaroa, whose guardian is the whale.
Mrs Patuawa got children to stand on one side of the whale and place their hands on the creature's body, telling them it would help to push the whale's spirit back out to sea, where it belonged.
Baylys Beach resident Parry Crabb said he and his grandchildren were on the beach in the morning when they saw a large tail bobbing up and down in the surf as the whale was being washed in.
It is believed that the whale may have already been dead when the body came ashore.
Tourist Brent Tuffley said he saw two men extracting teeth from the whale about 3pm, once the tides had receded.
A Department of Conservation spokesperson was not available for comment.
