Rud, Norway-based Nortek Group has provided the U.S. National Science Foundation, as well as scientists from the Commission for the Conservation of Antarctic Marine Living Resources (CCAMLR), with state-of-the-art technology to help them estimate krill biomass in the Southern Ocean.
Nortek provided a suite of moorings equipped with Signature100 acoustic Doppler current profilers (ADCPs) and gliders, which were deployed in waters near the Antarctic Peninsula last year in order to get a more accurate estimation of the regional krill fishery.
“The Southern Ocean has seen some significant changes over the last few decades. With the climate crisis, waters are warming, losing oxygen and salinity, and acidifying – all putting pressure on krill. The region has also seen an increase in commercial fishing directed at krill. For the management body charged with managing the Southern Ocean, CCAMLR, it’s a balancing act between allowing a fishery to take enough krill to allow it to be commercially viable and leaving enough for predators to eat – and letting enough krill survive to keep reproducing – all under rapidly changing conditions,” the company said in a press release.
Nortek is a maker of acoustic Doppler instrumentation, including ADCPs and Doppler velocity logs (DVLs), which are used for subsea navigation. It also offers real-time data collection and support. The Norwegian firm has subsidiaries in the United States, the United Kingdom, China, Japan, Australia, Brazil, France, and the Netherlands.
The Nortek equipment used by CCAMLR in studying the krill biomass is an integrated ADCP and an echosounder in one device, to allow a smaller number of technicians are needed to maintain and deploy them. The instrument’s ability to collect large amounts of data over several months (around 100 GB per instrument) means “fewer trips out to what is a very remote part of the planet,” the company said.
“Multiple simple moorings like the ones we have designed for this program generate near-complete time series of biological conditions in the vicinity of fishery areas, albeit at fixed locations. The gliders, although slow-moving, can provide the spatial context from which to interpret the mooring data – and can sample over months for a fraction of the cost of ship-based research,” said Christian Reiss, a fisheries scientist at NOAA’s Southwest Fisheries Science Center, who is part of a team whose research in the Antarctic supports CCAMLR’s management decisions.
Historically, krill surveys typically took place in the austral summer, which is also when all commercial krill fishing took place. However, “fisheries are now spending more time in the Antarctic, and have moved into other areas not covered by the surveys,” according to Reiss.
Specifically, China has vowed to double its krill-fishing activity over the next four years, and Norwegian krill-fishing firm Aker Biomarine is also scaling up. This heightened activity means it’s even more important to determine the ramifications of interactions between predators, fisheries, and krill, such as how fast krill come back into an area once a fishery has removed them, and how much overlap between fishery and predators occurs, Reiss said.
“If fisheries are targeting krill in the same places used by predators, then fishing a small amount of krill could have a bigger impact on predators than if a larger amount of krill were fishing elsewhere,” Reiss said. “As fisheries are starting to harvest krill resources to feed the world’s population, this must be done in a sustainable manner, based on accurate, scientific observations.”
From a management perspective, defining what is amount of fishing is sustainable requires having data at appropriate time and space scales, which is where Nortek’s autonomous technology is playing a role, Reiss said.
“Because the research will operate over many years, calibration and a standardized setup prior to deployment have been essential,” he said. “[Year in, year out], if one instrument measures 10 grams of krill, the other one should be measuring 10 grams of krill for the same amount of acoustic energy that comes back. That standardization becomes critical to understanding the amount of krill that is in the system.”
Reiss said the Signature100 ADCP has proven efficient at identifying krill as they move throughout the water column and with currents.
“The data we’ve collected so far has been very high-quality data, with a good signal-to-noise ratio. That’s allowed us to be confident that we can move forward with estimating the krill biomass that is critical to our work,” Reiss said.
Reiss said the project should be finished in the next two to three years.
“The data we have collected with these instruments will be used by CCAMLR to understand all manner of interactions between krill, their predators and the fishery,” Reiss said.
Photo courtesy of Nortek
