Scientists say the humpbacks may have been malnourished while forced to compete for food with a burgeoning industry harvesting the tiny crustaceans - the linchpin in the Antarctic food web - for use in pharmaceuticals and fish feed. The fishing company, Norway's Aker BioMarine, said these were its first cases of whale bycatch in 15 years of harvesting krill in Antarctica, and that it has since reinforced its ships' devices for keeping marine mammals out of its nets. Pål Skogrand, director of Antarctic affairs and sustainability at Aker BioMarine, said the company "has no desire" to be part of this global problem. But with the krill industry set to grow significantly in the next decade - as nations including China and Russia plan new investments in the business - scientists and conservationists fear krill trawling could further imperil Antarctic wildlife. The krill trawlers target the same foraging grounds as fur seals, humpback whales, and blue whales. Penguins are also struggling when fishing vessels are nearby, with studies describing the birds having to swim for longer periods in search of food for their chicks. "Krill fishing is an acute example that we are fishing down the food web," said Teale Phelps Bondaroff of the conservation non-profit OceansAsia. "That doesn't bode well for our global fisheries. It means we're getting to the end of what's available in our oceans." POLAR ABUNDANCE The icy waters off Antarctica are estimated to hold between 300 million and 500 million tonnes of krill - nearly as weighty as all of the world's cattle. This perceived abundance led Soviet fishing fleets to target Antarctic krill in the 1970s, scooping up hundreds of thousands of tonnes per year until the Soviet Union collapsed in 1991. Their surveys make Antarctic krill relatively well researched, compared with the 84 other krill species in the world's oceans. Governments have resisted opening new krill fisheries due to conservation concerns, though both Japan and Canada operate small krill fisheries in the North Pacific. On the southernmost continent, about 11 vessels from China, Norway, South Korea, Ukraine and Chile trawl the region's choppy waters from December to July. Under established rules within the Antarctic Treaty System, trawlers must stay largely confined to four areas off the Antarctic Peninsula, with a seasonal catch capped at 620,000 tonnes - less than 2% of the species. Due to the expense and ice cover, fishing vessels have yet to take the full quota. But in 2020, they scooped up 450,000 tonnes - the most recorded in decades. China more than doubled its take from the previous year. "If we introduce just a couple more big trawlers we will reach (620,000) tonnes very easily," said Rodolfo Werner, senior advisor of the Antarctic and Southern Coalition, a group of environmental non-profits. "This has always been our concern." The world's krill industry is still modest in economic terms. But it is growing fast, with the $531-million market for krill oil - one of the key products - projected to rise to $941 million by 2026, according to a report last month by Global Industry Analysts. Fish farming, for which krill is used as feed, is the world's fastest growing food sector, with analysts expecting global demand for fish to double by 2050. "Krill contain so many good elements, such as omega-3s," said Skogrand, disputing the argument that krill should be left to nourish wildlife alone. That's "not the way to secure food production in the world." Norway's Aker BioMarine, which accounts for more than 60% of today's krill catch, added a third ship to its fleet in 2019, as the company "increased our catches significantly in the past five to ten years," said Skogrand. Contacted by Reuters, Chinese companies involved in krill fishing declined to comment. The country's fishery management bureau said last year its krill fishing fleets had reached an "international level" of efficiency, citing unspecified breakthroughs in industrializing krill production. In a statement to Reuters, the foreign ministry said China "attaches a great importance to conservation and rational use of the marine biological resources of Antarctica." China "will definitely grow," said Dimitri Sclabos, the CEO of the Chile-based krill consultancy Tharos. "They have built several factories for extracting krill oil. There's a huge market." Russia has announced plans to invest 45 billion roubles ($604 million) in the fishery, including building five high-tonnage trawlers. "The development of krill fishing is part of the policy of the Russian Federation to renew the activities of the Russian fishing fleet in remote areas of the world ocean," Russia's state fishing agency told Reuters in a written statement. SUPPLY PRESSURE Mindful of the threat krill fishing poses to penguins, eight krill fishing companies in 2018 pledged to stay at least 30 km away from key breeding colonies during incubation and chick-rearing season. An analysis for Reuters by the Global Fishing Watch monitoring agency found that since 2019 the trawlers in operation have upheld that promise. Even without competition from fisheries, the krill supply is under increasing pressure due to both climate change and a partial rebound in whale numbers since the end of commercial whaling. A 2016 study in the journal Geophysical Research Letters found warmer waters and increased ice melt could drive krill numbers down about 30 percent this century. "We have limited knowledge of the resiliency of krill to warming," Bettina Meyer, a marine biologist at the Alfred Wegener Institute, told Reuters while on a research trip aboard the RV Polarstern in Antarctica. Polar scientists say even current limits on Antarctic krill fisheries may not go far enough to safeguard the food supply for wildlife. A single humpback whale in the West Antarctic Peninsula eats up to 3.1 tonnes of krill a day. The region has an estimated 3,000 humpbacks. The seasonal catch "is actually being taken from a much smaller area than for which it was appropriately calculated," said George Watters, director of Antarctic research at the US National Oceanic and Atmospheric Administration. He led a February 2020 study published in Scientific Reports that found penguins were failing to raise as many chicks when 10% or more of the krill was removed from a nearby area. In October, the Commission for the Conservation of Antarctic Marine Living Resources will consider revising catch limits and trawling zones, due to conservation concerns. It declined to give details of the proposed changes. Approval requires a consensus vote by all 26 commission members. Scientists fear some nations may object to stricter measures. Beijing and Moscow have been notable opponents of efforts to establish Marine Protected Areas in the region. The Russian state fishing agency, noting the "impressive" krill stocks in the region, said any changes would have to be "clearly justified" by scientific evidence. "There are not many areas open to fishing."