NIWA scientists have discovered that cryptic deepsea markings match the mouths of grenadiers. Photo: NIWA/ supplied
The origins of cryptic deepsea markings in New Zealand oceans have been discovered by NIWA scientists.
Researchers observing footage from a Chatham Rise 2013 survey found horseshoe-shaped imprints, but had no clue what they were - until now.
The scientists, including NIWA's invertebrate collection manager Sadie Mills, sent several pictures to NIWA fisheries scientist Darren Stevens from the survey and asked if the markings were caused by a deepsea rattail - a fish also known as a grenadier.
Stevens overlaid head profile images of specific rattails alongside pictures showing defined seabed impressions.
He said the team were able to pin the markings on two of the 70 grenadier species that were known to live in New Zealand waters.
"The reason we could point to a specific species is because of their unique head features - these types of rattails have a long snout and an extendable mouth on the underside of their head that allow them to feed off the seafloor, something that other species do not," Stevens said.
When comparing the images, they fitted perfectly together, he said.
"I had a hunch this might work, but I was really surprised how well the head profile images matched the impressions.
"We were able to provide fairly good evidence that these impressions were made by two grenadier species.
"This new discovery could allow future surveys to identify soft sediment feeding areas and critical fish habitats for these species, which are a key part of the ecosystem," Stevens said.
Grenadier feeding in New Zealand deepsea waters. Photo: NIWA/ supplied
Mills said despite seeing mysterious traces of life in the deepsea, there was usually not enough evidence to prove what type of species caused them.
"NIWA uses a technology called the Deep Towed Imaging System (DTIS) to allow us to see the seafloor in stunning detail.
"When our people review this footage, they often see markings in the sediment, but unfortunately most of them are unknown to science and we can only guess what might have made them, let alone find convincing proof.
"It's so cool to finally have the validation that what we saw on the video was actually rattails feeding in the mud. It's like getting a nice reward at the end of many years of watching DTIS footage," Mills said.