When a team of scientists headed out on a voyage last month to survey hoki – a commercial fish species found most commonly off New Zealand’s coast – a giant squid was hardly what they expected to encounter.

Researchers aboard the Tangaroa, a vessel belonging to the National Institute of Water and Atmospheric Research Ltd (NIWA), hauled up their trawler net* late last month and were surprised by the sight of large tentacles intertwined with the catch.

The tentacles belonged to a deceased 4-metre long, 110-kilogram giant squid which – despite its impressive figures – was “on the smallish side,” according to NIWA fisheries scientist Darren Stevens. It took six members of the crew to lift the squid out of the net and onto a tarp. Many scientists were snoozing when the squid was discovered, but word quickly got around and before long the vessel was buzzing with excitement.

"We knew there would be staff who wouldn’t be happy if we hadn't woken them for a giant squid,” quipped Stevens.

It’s unclear if the animal perished in the net or if it was dead before the researchers recovered it, but its body may help uncover some of the mysteries surrounding these almost-mythical creatures.

Auckland University of Technology squid researcher Ryan Howard was onboard and carried out an examination and dissection of the animal. Scientifically valuable samples were removed from the squid for later study. Howard’s research is focused on the eyes of giant squid so he jumped at the opportunity to get his hands on fresh specimens to study. “It was a really unique set of circumstances to get two fresh eyes,” Stevens said in a statement, adding that entire scientific papers can be compiled from the eyes of the animal alone.

The stomach was also removed in order to study the squid’s diet – something which has proved surprisingly tricky as previously caught animals usually turn up with empty bellies.

In order to better understand the life cycle of the giant squid, a tiny bone structure called a statolith was removed from the animal’s head. It will be used to estimate the age of the squid.

While these deep-sea denizens are rarely seen, New Zealand is “kind of the giant squid capital of the world,” Stevens explains. “Anywhere else a giant squid is caught in a net would be a massive deal, but there’s been a few caught off New Zealand.”

They are, nonetheless, very rare and this is only the second specimen that Stevens has come across over the course of a number of surveys.

The squid wasn’t the only exciting find on the expedition; the voyage also turned up several bioluminescent sharks. Unlike the surprise squid, this glowing discovery was entirely expected. Dr Jérôme Mallefet of UCLouvain, a French-speaking university in Belgium, joined the voyage with the specific goal of finding deep-sea sharks that glow.

According to Mallefet, at least 11% of all known shark species can emit bioluminescent light – most of these are small sharks that dwell at depths of more than 200 metres. They glow for a number of possible reasons: avoiding predation, attracting prey or for courtship and schooling.

Seal shark (left) and lucifer dogfish (right). Image © Dr J.Mallefet

To document bioluminescence, Mallefet set up a dark lab aboard the research vessel to mimic the pitch black conditions of the deep sea. Using specialised cameras he photographed a southern lantern shark, lucifer dogfish, and a seal shark that had been caught during the expedition, marking the first time that light-producing sharks had been recorded exhibiting bioluminescence in New Zealand waters.

“I was so happy. I was dreaming to get pictures of bioluminescent sharks [on the voyage] and I got them,” he said in a media release.

*Trawler nets are sometimes used by researchers to gather information about important marine species. Some ethical questions have been raised regarding this research methodology. More here.