A scientific expedition to Antarctica is expected to explore new parts of the Ross Sea this month - but there are positives and negatives to the increased access.

Photo: Dave Allen, NIWA

Before now, much of the south-east portion of the newly created Ross Sea Marine Protected Area (MPA) was blocked by sea ice.

But this year experts are confident of getting deeper into the Antarctic region with the sea relatively free of ice for the second year running.

That is great news for scientists hoping to look into the impact of the toothfish fishery in the region, and that of the entire ecosystem.

It is bad news for climate scientists, with the amount of ice described as concerning.

The National Institute of Water and Atmospheric Research is leading the expedition on its ship, the Tangaroa.

Photo: SUPPLIED / NIWA

Peter Sanderson, the ice pilot for the voyage, said the Ross Sea is more open than usual.

"It's open due to the fact that, there are certain criteria that usually you can go back through history and see the expansion and contraction of ice, and how it moves," Mr Sanderson said.

"There's a whole science behind it, but this year there's a lot of open areas that generally are quite difficult to navigate in due to ice concentration.

"It was open last year too, so it's a little worrying. I haven't seen this trend for a long time."

Mr Sanderson said the scientists will be studying the amount of ice in the area, and what that could mean for climate change.

A lack of ice gives other scientists the opportunity to explore, and get more information on the marine life in the area.

Toothfish main target of some scientists

NIWA principal scientist Matt Pinkerton said he is interested in the toothfish population at the bottom of the Ross Sea, and how the toothfish affect other species in the area.

Photo: NIWA

Researchers are looking at all levels of the foodchain, including seals, penguins, and if they're lucky, sperm whales.

"We know that sperm whales eat a lot of toothfish, but no-one has seen sperm whales in this area for a long time," Dr Pinkerton said.

"So we're going to listen for them to see if they're actually there and just hiding from people.

"We put out some short-term deployments of acoustic sensors just north [of the area], and that picked up some sounds of sperm whales.

"My guess would be that there are sperm whales there, but they're staying away from vessels."

NIWA has three listening buoys in the protected area, the southern most of which will be difficult to reach if there is too much sea ice. As things stand, they're confident of reaching the buoy.

The protected area was only created in December 2017.

Dr Pinkerton said it is early days in exploring the region, and for now scientists are seeking to get baseline data for a number of areas of research.

"Often when Marine Protection Areas are set up, they're set up in perpetuity, but this MPA isn't like that," he said.

"It's set up with a 35-year lifespan, so if after 35 years we can't show that the MPA has had a positive effect on protecting the ecosystem in the Ross Sea, then the likelihood is it won't be continued beyond that time.

"So what we're trying to do now, when the MPA was established, was set the baseline.

"If you think of it like looking at the dashboard on your car, we're trying to work out which dials we should be looking at. You don't want to be looking at the radio if we want to work out if we're going to run out of petrol."

The expedition, which includes 21 scientists and 19 crew members, leaves tomorrow afternoon. The voyage will last until the middle of February.