Scientists say the size of the eye suggest the colossal squid is a mostly visual creature. Photo / Mark Mitchell

Scientists say the size of the eye suggest the colossal squid is a mostly visual creature. Photo / Mark Mitchell

It's a tale familiar to fishermen all over the world - the catch never seems quite as big as it was when anglers were swapping stories at the pub.

Scientists at the Museum of New Zealand were left with a bit of a damp squib last night as their three-day thaw of snap-frozen 495kg colossal squid tonight turned out to be only 4.2 metres long.

It was a long way short of the 10m estimated by longliners on the vessel, San Aspiring, when they hauled it to the surface, gnawing on a 30kg toothfish hooked 1800m under the icy Ross Sea.

Early interviews with the skipper of the Nelson trawler produced an estimated length of 10m.

At the time, Fisheries Minister Jim Anderton breathlessly announced " it is likely that it is the first intact adult male colossal squid to ever be successfully landed" and said the species were estimated to grow up to 12 to 14 metres long.

Oops.

The thawed colossus of the deep last night turned out to be a little shorter, and female.

"The two long tentacles that the fishermen observed have shortened and shrunken considerably post mortem, giving a final total length of 4.2m," museum worker Chris Paulin said on the museum's "squid blog".

Even as recently as Monday, when the specimen snap-frozen into a metre-wide ice cube was brought out to thaw, scientists were estimating it would be 6m to 8m long.

But they were still thrilled with measurements of the main part of the half-tonne specimen's body, known as the mantle, which showed it was similar to a 2.5m length recorded for an immature female at the museum in 2003.

The squid - which some jokers have suggested should be named "Thor" - weighed 195kg heavier than the 2003 example, which had a total length of 6m.

"These are incredibly plastic animals, and dimensions obviously change considerably," said Mr Paulin, the projects manager at the museum.

But a key indicator of size in the species - the hard "beak" with which it chops 2m Antarctic toothfish into bite-sized fishy chunks - does not shrink. Yesterday's measurements showed a the standard "rostral" length of the beak was 41 mm, compared with 37mm for the 2003 female.

"Beaks up to 49mm have been found in sperm whale stomachs ... this animal must attain much much bigger sizes than this," said Mr Paulin.