William MacKenzie with his surprise catch just before Christmas.

Four-year-old Ollie MacKenzie struggles to hold the 4.4 kilogram lobster his brother William, 8, caught on a fishing trip in Queen Charlotte Sound.

What a whopper. The crayfish stops for a break.

This is a tale of a (cray)fish that didn't get away.

Eight-year-old William MacKenzie, from Blenheim, was in a boat with family in Queen Charlotte Sound fishing for blue cod when he pulled up a 4.4 kilogram (9.8 pound) crayfish on his fishing line.

1 of 9 Supplied Chris says this cray was caught way back in 2004. 2 of 9 Phil Kerwin This crayfish was caught off the south Taranaki coast over Christmas. Both specimens weigh about 4kg. 3 of 9 Supplied This one was snared near D'Urville Island. 4 of 9 SUPPLIED William MacKenzie with his surprise catch just before Christmas. 5 of 9 Dean Wyborn Dean Wyborn's Christmas Eve cray. 6 of 9 Nathan Pilkington Nathan Pilkington collected this 3kg cray while free diving off the Akaroa coast. Holding it is his fearless 7-year-old daughter, Nevada. 7 of 9 Glenn Hogg Glenn Hogg and friend with their catch from a "secret location". 8 of 9 Josh Driscoll Josh Driscoll caught this crayfish last summer in the Queen Charlotte in the Marlborough Sounds. It was cooked in a wheel barrow because no-one had a pot big enough. 9 of 9 Rebecca Hudson A 28-pound snapper caught by one reader's husband a couple of weeks ago.

Have you caught a bigger crayfish? What about other holiday fishing whoppers? Send your photos, video or tips to newstips@stuff.co.nz

The colossal crustacean even stunned a man with 30 years of experience in the lobster industry, who said it was the biggest he had heard of.

Whopper: Four-year-old Ollie MacKenzie struggles to hold the 4.4 kilogram lobster his brother William, 8, caught on a fishing trip in Queen Charlotte Sound.

William's dad said the family were on their 5.5-metre boat on December 23 fishing for blue cod and sea perch when William got his hook caught on what they thought was the sea floor.

But it came up and he thought it might have been seaweed, but once the group realised what it was they scrambled to get a landing net, he said.

William landed the beast, aka a spiny red rock lobster, on his own, his dad said.

Big surprise: Those on the boat at first thought William MacKenzie had hooked the sea floor, not any kind of catch.

The crayfish was weighed back at shore.

The family were in an area where they fish regularly and was not renowned for lobsters or as a spot for diving.

Cramac 5 executive officer Larnce Wichman said the lobster was the biggest he had heard of and was stunned when shown the photos.

"I don't know if there are any records kept [for crayfish sizes], but it'd be damn close to it."

It was "near impossible" to tell the age of a lobster once it grew to more than 800 grams because its size depended on where it lived and the food sources available to it.

"The problem with ageing anything over 2kg is that it doesn't necessarily moult every year, but [this lobster] could easily be 50 years old."

It was not uncommon to snag a lobster on a fishing line, but the more popular methods were diving or bobbing.

Bobbing involved lowering a stocking filled with bait and weighed down by a sinker which catches the spiny legs of the lobsters as they feed.

Wichman said if he had known about the lobster he would have offered to swap it for several others so it could be stuffed.

However, the family had already eaten the lobster on Christmas Day. They said it tasted delicious.

* Correction: This story originally said the crayfish was 9.8 kilograms. It was in fact 9.8 pounds (4.4 kilograms).