Ice floating on the sea in Antarctica. (Photo: Eitan Abramovich/AFP/Getty Images)

Krill oil, rich in heart-healthy omega-3 fatty acids, is a popular nutritional supplement around the world. However, according to a recent report from Greenpeace, growing demand is fueling commercial fishing in Antarctica's icy waters that could make it harder for all kinds of polar marine life to survive climate change threats.

A tiny cold-water-living crustacean, krill isn't eaten by humans. It is fished in parts of Antarctica's Southern Ocean to make nutritional supplements as well as pet, livestock, poultry, and aquaculture feed. But polar marine wildlife—including penguins, seals, whales, fish, and birds—also depend on krill as a major part of their diet. The Southern Ocean teems with an estimated 379 million metric tons of krill.

Regulators of Antarctica's krill fishery have already implemented rigorous rules to ensure sustainable fishing levels according to current available science, said Phil Trathan, a scientific adviser to the Commission for the Conservation of Antarctic Marine Living Resources and a senior scientist at the British Antarctic Survey. CCAMLR, the governing body that oversees krill stocks, asserts the fishery is one of the world's best-managed and includes a strict licensing and catch-reporting system.

But while the industry and its regulators might be focused on good management, Greenpeace argued that krill fishing is placing unnecessary pressure on sensitive ecosystems in a part of the world's oceans already greatly threatened by melting sea ice and rising ocean temperatures. These activities could also impede ongoing marine protection efforts, according to Luke Massey, global communications lead of Greenpeace's Protect the Antarctic program.

"There is a clear overlap between the countries most strongly opposed to marine protection and those with an active krill fishing industry in the region," he said in an email. "As the largest fishery in the Antarctic Ocean, the krill industry represents a significant lobby capable of transforming efforts to create ocean sanctuaries in the Antarctic."

In the report, Greenpeace detailed its use of public data to track five years of krill fishing vessel activities around the Western Antarctic Peninsula, the part of the continent that extends up toward South America and is both the major area for the krill fishery and a feeding ground for penguins and whales. Krill fishing levels have increased in the area in recent years. In 2010, according to the report, fishing hit the maximal allowed level of 120,000 metric tons for the first time in the West Antarctic Peninsula region and has several times since—triggering the early closure of season's fishing. In these years, the report said, vessels from Norway, South Korea, and China have ramped up activities and new ships are also being built.

In tracking vessel movements, Greenpeace noticed "a pattern of fishing activity increasingly close to shore and in the immediate vicinity of penguin colonies, which depend on krill." Their findings—based on analyzing automatic identification signals, which show movements of krill trawlers, and cargo and tanker vessels—found vessels that appeared to be transferring catch at sea to large refrigerated cargo ships, a practice called transshipment that has raised concerns about illegal fishing elsewhere. The report identifies at least two of these cargo ships, called reefers, as having been involved in previous pollution or safety violations. Some ships were anchoring close to a specially protected area, which can damage the seabed and is discouraged by the CCAMLR's rules, according to the report. Other concerns raised by Greenpeace include the risk of oil spills, fires, or groundings in relatively pristine waters.

Greenpeace, which is among a number of conservation groups and governments pushing for expanded marine reserves in the Southern Ocean, is calling on krill-buying companies to stop purchasing catch from vessels that fish in areas that are currently under consideration for protection by the CCAMLR. The environmental group is also urging ships to voluntarily stop fishing in sensitive areas and asking fisheries managers to support conservation goals.

In 2016, the CCAMLR voted to create the world's largest marine protected area in Antarctica's Ross Sea. It is also considering other protection proposals, including creating a 700,000 square-mile protected area in the Weddell Sea, as well as in the waters around the Western Antarctic Peninsula. The latter area is the ecologically important region that krill fishing boats currently frequent. Greenpeace, according to Massey, worries that there will be pressure for fishing efforts to expand beyond current levels.

Scientists Mark Belchier and Simeon Hill with the British Antarctic Survey said in an email that the timing of Greenpeace's report criticizing the Antarctic krill fishing industry is not surprising, given their ongoing Antarctic Ocean campaign that has "garnered much publicity."

They noted it is highly unlikely that krill fisheries would ever expand to a place like the Weddell Sea—which also abuts the Antarctic Peninsula but currently has no krill fishing. "Opening up a krill fishery in this region would have to be based on scientific evidence and consensus reached among all CCAMLR members—this is highly unlikely," Belchier and Hill said.

In the future, climate change could hurt krill numbers because they have a complex life cycle that is dependent on stable ocean conditions, according to a recent study. One important factor in their survival is the existence of sea ice, which they use for shelter and feeding on algae. A loss of sea ice, or change in seasonal timings, could hurt krill populations and those that depend on them.

Trathan noted that, "so long as CCAMLR members follow the correct procedures, they are legally allowed to fish for krill in this remote and hostile region." He said the Antarctic krill fishery could help support global food security as human populations grow, as long as it continues to be sustainable.

Ensuring it is sustainable, he said, requires provisions like precautionary catch limits that allow enough time for krill to repopulate seas, continued scientific research, and protections in sensitive areas. "It is vital that the fishery is managed to the very highest possible standards," he said.

This article originally appeared on Oceans Deeply, and you can find the original here. For important news about our world’s oceans, you can sign up to the Oceans Deeply email list.