Countries are loosely interpreting the legal meaning of "rational use" of natural resources to escalate fishing efforts in Antarctic waters and hinder efforts to establish marine protected areas in the Southern Ocean, scientists and legal scholars say.

The findings, published online in the journal Marine Policy, come as 24 countries plus the European Union convene in Hobart, Australia, this week for the annual meeting of the Commission for the Conservation of Antarctic Marine Living Resources (CCAMLR) to set fisheries management rules in the Southern Ocean.

Also on the meeting agenda are plans for extensive marine protected areas (MPAs), including the Ross Sea, Antarctica, a region scientists have deemed Earth's "Last Ocean" because it is perhaps the healthiest large intact marine ecosystem left on the planet.

"Largely protected by an icy shield and sheer remoteness, the southernmost waters around Antarctica are the least affected by people. They also contain some of our last pockets of untapped fish stocks," said co-author Cassandra Brooks, a PhD candidate in the Emmett Interdisciplinary Program in Environment and Resources (E-IPER) at Stanford University's School of Earth, Energy and Environmental Sciences.

CCAMLR is tasked with managing the waters around Antarctica and is considered a global leader in fisheries management that prioritizes conservation. As part of that leadership, it has been moving toward adopting an extensive network of MPAs to conserve the ecosystem and protect biodiversity in the Southern Ocean. Yet, in recent years, their progress has stalled, in part due to willful misinterpretation by member countries of the law that governs its icy waters.

As its name states, the goal of the commission is conservation, but under its legal Convention - the international treaty that governs the Southern Ocean - conservation includes "rational use," which allows for fishing in the Antarctic waters, but under strict and precautionary conditions.

For example, it requires that fishing does not cause irreversible damage to the greater marine ecosystem. While defined in the text of the legal Convention, the term is increasingly being interpreted to mean an unfettered right to fish. Even more surprising, countries such as China and Ukraine have recently invoked rational use to protest the adoption of marine protected areas in the Southern Ocean.

"Our research into the treaty negotiation record shows that 'rational use' on its own did not have a clear, consistent, or objective meaning," said lead author Jennifer Jacquet, an assistant professor in New York University's Environmental Studies Program.

"In recent years, some countries have argued that MPAs interfere with their right to rational use," Brooks said. "Yet adopting MPAs in CCAMLR waters is in complete accordance with stipulations of rational use, which require conservation of the fished species and the greater ecosystem in the Southern Ocean."

Currently, the main species harvested in the Antarctic are Antarctic krill and Patagonian and Antarctic toothfish, also known on the market as the lucrative "Chilean sea bass."

"The Southern Ocean is a global commons. As such, marine protected areas would allow CCAMLR member states to continue fishing while also ensuring a legacy for future generations," Brooks said. "What could be more rational than that?"