Text box: Scientists are voyaging into the Southern Ocean to measure Antarctic krill from all angles.
Text box: Using novel technologies they will estimate how much krill live in the waters off Mawson station.
Text box: Echosounders on RV Investigator can 'see' vast krill swarms under water and measure their 'biomass'.
Krill biologist – Rob King: So the principal method used in this voyage will be echo sounding the krill, and that's basically a glorified scientific fish finder. So we'll use those echo sounders to estimate the biomass of krill, that's how we measure it, but we also check that they really are krill by putting a net through these schools occasionally. And it also tells us about the type of krill that are in there, are they males, are they females, are they carrying eggs, what size are they. And all of this information refines our biomass estimate even further, and gives us much more confidence about that estimate.
Text box: For the first time, deep sea moorings will reveal how krill use the sea floor.
Rob King: There have been over 40 different occurrences now where krill have been recorded on the sea floor. Down as deep as three and a half kilometres deep. And we just don't know how important the seafloor benthic habitat is for krill. And if we're estimating biomass with an echosounder on the surface that can only see down 350 metres, how much of the population might we be missing all the way down to the sea floor?
Text box: The team will also study predators and ocean properties.
Text box: Their work will help set a precautionary catch limit for an expanding krill fishery.
Voyage Chief Scientist – So Kawaguchi: Setting precautionary catch limits, it's not only about krill biomass, but also understanding the relationship between the predators and the krill, and the environment. Because if you take too much krill, that may take too many krill for the food, for the predators, and that's the sort of thing that we really want to avoid.
Text box: The voyage will survey krill across more than 793,000 square kilometres.
So Kawaguchi: The last time that we surveyed in that area of Mawson coast is 2006, which is quite a long time ago, so we really have to update the understanding of that region so that we can, you know, update the precautionary catch limits and also the management strategy, to make sure that we have a good management system before the krill fisheries takes off again.
Text box: The research is critical to the sustainable management of krill and the predators that rely on them.
Rob King: Antarctic krill live in a unique environment, and they're perfectly adapted for it, but it's also one of the environments that is changing extremely fast with climate change at the moment. Laboratory research that we've done has shown that the acidification caused by dissolving carbon dioxide, has the potential to cause a 50% reduction in krill hatch rates by the end of this century if we did nothing to slow our carbon dioxide emissions. That would have a really important flow-on effect to biomass and how we managed the fishery. So understanding the environment, and the changes it can have on krill, is absolutely critical if we're going to manage this ecosystem to ensure the conservation of the species and those that depend upon it.