Broadbill swordfish grow to more than 600kg, he added, but were a natural prey of mako sharks, which will attack them from below, removing the tail, then, having incapacitated it, will bite off its long sword-like bill to prevent it fighting back. Only then will it feast on its kill.
In this instance however, both shark and fisherman wanted the swordfish, and Matt and Julian managed to drag it aboard, albeit not before the mako had taken its share.
"It's a graphic example of what these predators are capable of," Matt said, "but while it seems shocking, it's just a fish eating another fish, a scenario that is being played out millions of times every minute in the ocean. What makes this encounter special is the size of the fish involved and that it was caught on film."
He was quick to dismiss any talk of shark attacks on humans, however.
"We just happened to be in the perfect position to witness what happens every day in the ocean," he said."Most people are blissfully unaware that there are sharks all around us, but they've got no interest in eating us. Why would they eat a smelly human when they can have a feed of tasty swordfish?"
The remains of the swordfish were carved up and shared among dozens of Far North families.
The encounter will feature in the new series of The ITM Fishing Show that started on Saturday (5.30pm on TV3).