The 3.6-metre, 460-kilogram shark died in the Mapua channel last month.
Conservation Department shark expert Clinton Duffy, who carried out the dissection, found an empty stomach and that the mako gave birth recently. The autopsy indicated it may have been killed by an encounter with a boat.
There was massive bruising behind its jaws, Touch the Sea aquarium marine educator Richard de Hamel said. "So it may have been feeling a bit sick, then got a bump on the head, and that's really put her on the downhill slide."
The condition of the shark's uterus showed it had given birth within the past few months.
A sample of its spine was taken and its growth rings will be used to determine its age, which was probably about 30. Video here.