New research shows how marine protections in the Antarctic Peninsula, one of the fastest-warming places on the planet, would benefit krill, their predators, and the region’s krill fishery— the largest in Antarctica.
The thumb-sized crustaceans are the center of the region’s marine ecosystem and the key to a healthy Southern Ocean.
The timing of the research is auspicious: The Commission for the Conservation of Antarctic Marine Living Resources (CCAMLR) started its annual meeting on Oct. 22 to decide whether to designate new marine protected areas (MPAs) in East Antarctica; the Weddell Sea; and the Antarctic Peninsula, which could be the most threatened region in the Southern Ocean. Studies show that MPAs can help vulnerable ecosystems build resilience to climate change by eliminating additional stresses such as fishing.
Interest in krill in the peninsula, the northernmost portion of the continent’s mainland, is shared between predators—including penguins, seals, and blue whales, which can eat several metric tons of krill in a day—and industrial fishing.
But krill are under threat: Research shows that waters warmed by climate change are disrupting krill growth and causing loss of habitat in the Southern Ocean, while concentrated fishing is reducing the locally available amounts of krill for land-based predators. This has led to negative impacts on penguins, including population declines for certain species.
Researchers Emily Klein and George Watters published a study, as did—separately—a team led by Adrian Dahood (Klein and Watters 2020, Dahood et al. 2020), that used dynamic food web models to evaluate the future effectiveness of the proposed Antarctic Peninsula MPA. Unlike previous research— which didn’t account for changing ecosystems, including shifts in species habitat caused by warming waters—the groundbreaking analyses were able to test whether an area would be effectively protected by an MPA in the future, given the impacts of climate change.
The Klein and Watters research showed that a well-designed Peninsula MPA that prevents fishing within 50%-75% of the foraging ranges of land-based predators could have positive outcomes for both krill-dependent predators and the krill fishery. The investigation highlighted the importance of extending protections for specific seal-foraging habitats. Critically, it also showed that benefits to the ecosystem and to the fishery, in the form of increased krill catch sizes, can occur even when limits on krill fishing within the MPA increases the amount of fishing outside the protected area.
The research team led by Dahood found that as sea ice decline in the northern portion of the Antarctic Peninsula drives krill populations south, establishing a no-take zone in the southern region could have positive outcomes for both krill populations and krill predators. The research also confirms the value of establishing MPA no-take zones in key areas around the tip of the Antarctic Peninsula, specifically Bransfield Strait and around Elephant Island. These are important foraging grounds for gentoo and chinstrap penguins, and where feeding fur seals and penguins commonly overlap with industrial krill fishing operations.
After Klein, Watters, and Dahood carefully compared the results of their two distinct models, the researchers discovered that by using no-take zones to shift industrial fishing away from important krill and predator habitats in the proposed Antarctic Peninsula MPA, krill and predator populations increased. And when projected climate change impacts were introduced into the model—such as record-breaking high temperatures, continued depletion of sea ice, and shifts in species’ ranges—the benefits to krill, predators, and the krill fishery remained.
As CCAMLR considers the designation of the Antarctic Peninsula MPA, it is concurrently updating its ecosystem-based management system (EBFM) for the region’s krill fishery. An EBFM approach prescribes where, when, and at what level krill can be caught, in order to lessen the risk of localized fishing impacts on krill-dependent predators. In an additional analysis, Klein and Watters compared one potential EBFM strategy with the proposed Antarctic Peninsula MPA, and found that the MPA would provide better outcomes for krill predators while increasing fishery catches. This was likely due to inadequate reduction of fishing risks to predators in the design of that potential EBFM system, which demonstrates the importance of strategically designing an EBFM strategy. In their analysis, the authors highlighted how a well-designed MPA and EBFM system could be used in tandem to benefit the Southern Ocean.
Preliminary results of the two distinct models were shared with scientists from Argentina and Chile, the countries responsible for developing the Antarctic Peninsula MPA (D1MPA) proposal that CCAMLR is considering. In response, the Argentinian and Chilean scientists in 2018 updated the proposed D1MPA boundaries to fully protect a southern zone where krill are projected to aggregate due to sea ice loss, as well as areas near fur seal colonies.
In a statement, Watters—who is also the U.S. scientific representative to CCAMLR—emphasized that “protection of the Southern region of the Antarctic Peninsula where krill are expected to concentrate under future warming is a key conservation feature of the Antarctic Peninsula MPA proposal.”
Klein explained to Pew in a recent interview that “by using two different models that incorporate the impacts of climate change and fishing in different ways, we found that the Antarctic Peninsula MPA could help CCAMLR meet multiple management objectives, including protecting krill predators and having positive outcomes for the krill fishery.”
An MPA in the peninsula would be only the third designation toward fulfilling CCAMLR’s commitment to create a network of large-scale protected areas in Southern Ocean waters. These studies are only the latest in a body of research that underscores the need for conservation in the region.
Funding for the studies was provided by The Pew Charitable Trusts.
Andrea Kavanagh is project director and Nicole Bransome is an officer with The Pew Charitable Trusts’ campaign to protect Antarctica’s Southern Ocean.