"I got it to about 50m from the shore and then it actually came disconnected from the line, so I got my son who is a good surfer to go out there and tie the line around its tail."
He said he was elated, and still a bit stunned, by the hefty catch.
"This is definitely the biggest fish I have ever caught. I must have got a bit lucky today."
Sherman believed he may have broken a national record by reeling in the first land-based marlin caught in New Zealand.
"I haven't heard of it being done before," he said. "They are usually caught off boats, a few kilometres out to sea."
He said it took four people to lift the fish, which was now prepped and cooking in the smokehouse.
Ian Sherman, Celcest Sherman, Ross Sherman and Aaron Sherman with the impressive marlin. Photo / Supplied