New Study Bolsters Case for Predator-Focused Management of Antarctic Krill Fishery

Antarctic krill are small crustaceans – they grow to around 2.5 inches (6.4 centimetres) – and are at the center of the Antarctic marine food web, critical as prey for many other species, including penguins, flying seabirds, fish, seals and whales. All of these iconic predator species depend upon krill as their main source of food.

Krill also eat carbon-rich phytoplankton and, in excreting their waste, send much of that carbon to the seafloor instead of leaving it at the surface where it could accelerate atmospheric warming. Because of this, the Southern Ocean is one of the largest carbon sinks in the world.

Because krill have such an important role in Antarctica, the existence of an industrial fishery for krill creates various problems. The krill fishery is the largest fishery (by catch weight) in Antarctic waters, and krill catches are highly concentrated in coastal areas that are also important as feeding grounds for many predators.

In 2019, the Commission for the Conservation of Antarctic Marine Living Resources (CCAMLR) agreed to update the rules governing the management of the krill fishery. Since then, CCAMLR has been working to develop a revised krill fishery management plan, one designed to limit catches in areas vital to krill predators while still allowing catches in other areas that were frequented less by predators.

While the revised plan was being developed, CCAMLR intended for the existing rules to be maintained. However, at CCAMLR’s annual meeting last year, part of the existing system expired before CCAMLR members could finalize development of the revised plan, so krill catches can now concentrate in areas preferred by industry, regardless of the needs of krill predators.

Now, recent science details the need for additional work on the revised krill fishery management plan, factoring in the needs of rebounding baleen whale populations. The study’s lead author, Phil Trathan, DSc, has been conducting research in the Antarctic for more than three decades. His interest in the krill fishery means that he has made 23 research trips to the Antarctic, working on krill, krill-dependent predators and climate change.

Trathan, who was honored by Queen Elizabeth II in 2018 for his Southern Ocean research, is a visiting professor at the University of Southampton, an honorary fellow at Bangor University and an emeritus fellow at the British Antarctic Survey. He retired in 2022 as the head of conservation biology at the Survey, where he also served as the senior ecological adviser to the U.K. Delegation to CCAMLR. He has published more than 300 peer-reviewed scientific research papers on the ecology and management of Antarctic marine ecosystems.

Q: How did you first get focused on Southern Ocean marine science?

Courtesy of the Subject

A: As a child I was fascinated by Captain Robert Falcon Scott and his exploits in Antarctica, particularly his tragic expedition in 1912. This interest later spurred me to read, amongst other books, Great Waters by Sir Alistair Hardy. Hardy was the zoologist on the voyage of the RRS Discovery to Antarctica in the mid-1920s, part of The Discovery Investigations, which had been funded by the British government to provide the scientific background for managing the commercial whale fishery in the Antarctic. Through his studies on zooplankton, he also became expert on the wider ecosystem. For his time, Hardy’s work and that of his colleagues was truly remarkable, delivering a broad ecosystem approach to understanding marine science.

I found the mixture of science and politics fascinating, but ultimately depressing, as the economics of marine resource exploitation outpaced the available scientific knowledge of the time. Eventually, overexploitation led to the near extirpation of the great whales, with the U.K. being amongst the four nations (Norway, Japan, and the U.S.S.R. are the others) that together harvested more than 90% of the whales taken from the Southern Ocean.

Sadly, this is a recurrent theme in resource management across the world. In the Antarctic there were successive periods of exploitation – first fur seals, then elephant seals, then the great whales and then fin fish – all managed without sufficient thought for the future.

Q: Fast-forward to your working life, where you eventually became head of conservation biology at the British Antarctic Survey.

A: I joined the British Antarctic Survey, or BAS, in 1990, working on the archive of data from a series of scientific research cruises that took place during the early 1980s. This work helped me comprehend the enormous gaps that still existed in our ecological knowledge – many of which still also exist today. This work eventually turned out to be vital for managing the growing fishery for Antarctic krill as it led to the first precautionary catch limit for the species, which limited krill catches in the southwest Atlantic.

Q: You also, about that time, began working with CCAMLR, the international body that manages fisheries in the Southern Ocean.

A: I submitted my first science to CCAMLR in 1992 and attended my first scientific working group in 1996. I’ve attended meetings every year since. I ended my career as the senior ecological adviser for the U.K. Delegation to CCAMLR, a role I held from 2006 until I retired in 2022.

Since its first meeting in 1982, CCAMLR has regulated fisheries so that they were managed with a long-term sustainable perspective. I found this exciting and refreshing, given that science was fully integrated into management. Moreover, CCAMLR followed a precautionary approach, which meant that exploitation could not outrun the science available. To me, this was a framework that I felt was really worthwhile, and one to which I committed my future career.

I’ve been extremely fortunate throughout my career. I’ve taken opportunities and made others that have allowed me to work closely with other scientists and policymakers involved in CCAMLR. I’ve worked on research ships, from permanent land-based research stations, from fishing vessels and from deep field temporary camps.

Ultimately my goal has always been towards precautionary sustainable management of marine systems.

Courtesy of Phil Trathan

Q: You’ve published more than 300 papers. Do you have a favourite area of marine science?

A: When I started at BAS, baleen whales were rarely seen and were not easy to work with. I therefore focused my efforts on those penguin species that live in Antarctica. Research on penguins can tell us a lot about an ecosystem; they are sentinel species. That is, they provide insights into ecosystem change, whether it be due to climate variability, climate change, fisheries impacts or other biological changes. All of this work has helped me better understand some of the gaps in our ecological knowledge, that if filled, would help improve fisheries management. Understanding ecosystem processes is vital for CCAMLR, as CCAMLR uses an ecosystem approach to fisheries management.

Although my work may have helped close some research gaps, other gaps are now opening up, so the next generation of scientists still has an enormous task ahead. Today climate change is raging, economic pressures are increasing, whilst baleen whale populations are now recovering. Projecting what the Antarctic will look like in five years’ time, or 10 years, or even longer, is still just too complex.

Q: So what would you say are the most important issues to address for the health of the Southern Ocean?

A: I’ve mentioned ecological change – whether from climate change, fisheries pressure or recovery of previously depleted stocks of baleen whale. Other important threats to the ecosystem include pollution and the introduction of species not native to Antarctica, including pathogens such as avian influenza. All of these have the potential to change the marine ecosystem in different ways, including in ways not yet foreseen.

Today the Southern Ocean is changing and is likely to change throughout the rest of this century. After 23 trips to the Antarctic, I’ve never yet seen a blue whale, but observations by others suggest that they may now be showing early signs of recovery. Humpback whales are already close to being fully recovered and are now abundant. Fin whales are also showing strong signs of recovery; on the other hand, sei whales, like blue whales, are still incredibly rare.

All of these baleen whale species feed upon krill, so they must be considered by krill fishery management authorities – this means CCAMLR. Importantly, though research efforts on baleen whales are improving, the financial resources to maintain baleen whale research and monitoring programs are still totally inadequate.

This is a problem because without adequate research and monitoring we could inadvertently move backwards, by fishing without understanding the ecosystem consequences of harvesting, much as our forebears did when they decimated populations of seals, whales and fish. It has taken decades for some of these species to recover, and it is still uncertain how long full recovery will take, if it does.

So it’s vital that we conserve the ecosystems that are an integral part of the Southern Ocean. That’s something that can only be achieved through science and knowledge of probable consequences.

When leaders deny that something is important, they’re refusing to take responsibility. Yet the current and future state of the Southern Ocean, indeed the state of the world ocean, requires that our political leaders step up and act responsibly. Civil society must be alert to such failings and call it out when they encounter it.

Q: Speaking of civil society, what do you think most nonscientists may not understand about Antarctica and the Southern Ocean?

A: The Antarctic and the Southern Ocean are geographically remote, and for the large part lie beyond areas of national jurisdiction. This means that they’re part of our common heritage and not the preserve of a few. As the regions are our common heritage, management should be inclusive of different views.

The Antarctic Treaty, which has been in force since 1961, explicitly recognises that it’s in the interest of all humanity that Antarctica shall continue forever to be used exclusively for peaceful purposes. Yet, of the 58 states that have agreed to the treaty, only 29 are entitled to participate in the consultative meetings that help formulate management decisions. Similarly, 37 states have agreed to CCAMLR, but only 27 are party to decision-making.

This means that only a relatively few states are eligible to participate in making management decisions as part of the Antarctic Treaty, or as part of CCAMLR, something that’s clearly unlikely to fully represent the needs and desires of nonmember states. In contrast, the member states of the United Nations comprise 193 sovereign states. The United Nations is the world's largest intergovernmental organization, and all countries have equal representation in the U.N. General Assembly.

Q: Can you say a little more about your work with CCAMLR?

A: It is important to recognise that my work has been as part of a team, including international scientists from many different CCAMLR members. No one can work in isolation if they want to achieve something; they have to collaborate, and everything depends upon teamwork.

During my time with CCAMLR, I’ve been a passionate supporter for the need to develop management approaches that take climate consideration into account. For example, I led the work that helped identify that waters beneath collapsing ice shelves and retreating glaciers should be protected from fishing and preserved for scientific exploration. Ensuring that these areas are protected allows scientists to investigate unique new habitats and study them as they change. I’ve also been at the forefront of work to better understand emperor penguins and the threats they face as climate change warms the ocean, leading to changes in their critical habitat, sea ice; emperor penguins are a true icon of the Antarctic and are at real risk from global warming.

I also led the delivery of the science underpinning the first marine protected area, or MPA, in CCAMLR waters (and incidentally the first MPA in the world that is wholly in areas beyond national jurisdiction).

Also, within CCAMLR I worked with others to develop a risk assessment approach that moves krill catches away from areas critical to natural predators to areas that are relatively less important. Subsequently, this led to the collation of all available data needed for the implementation of the revised krill fishery management plan in a pilot study focused on the Antarctic Peninsula. This work used data from many CCAMLR members; the pilot study was endorsed by CCAMLR in 2019 and remains the favoured CCAMLR approach for krill management.

Courtesy of Phil Trathan

Q: So what do you think CCAMLR needs to do differently to better protect the Southern Ocean environment and the species that live in it?

A: Firstly, and most importantly, CCAMLR needs to rebuild trust amongst members and return to the consensus decision-making approach. There are a number of bilateral conflicts deeply embedded in CCAMLR that must be resolved. Consensus requires active engagement and a willingness to seek solutions. It’s about cooperation between equals and requires that members explore their differences. The key to finding win-win solutions is to understand all the different needs and perspectives of members before forming a proposal. Building consensus then requires that members provide detailed objections to a given proposal, so that alternatives can then be identified.

Secondly, the rules that govern how much catch can be taken by CCAMLR fisheries need to be reviewed and tested, whether they relate to the krill fishery or to any of the other major commercial fisheries that CCAMLR manages in the Antarctic. The rules governing catch limits for krill were agreed more than two decades ago and have provided a safeguard whilst catches have remained low. Now, however, as catches are set to increase, these rules must be reviewed to ensure that they work as anticipated in the context of increased krill consumption by baleen whales and in the context of climate change.

Thirdly, when new catch limits are agreed for an area, any major increases should be incremental and staged over a number of years, in case major perturbations to the ecosystem occur and so catch limits can more easily be reduced.

Fourthly, ecosystem monitoring needs to increase so that the population status and trends of key predator groups (especially whales and penguins) can be determined. Most existing monitoring takes place in the summer, yet krill fishing is now shifting towards the autumn and winter. Without adequate data about the ecosystem and about krill predators, CCAMLR won’t be able to determine whether fisheries are having long-term impacts on the ecosystem. An absence of monitoring does not mean an absence of impacts; it simply means that CCAMLR might not detect the impacts until long-term damage has already taken place.

Fifthly, science is needed to disentangle the plausible impacts of climate change from other drivers of change, such as fishing. This means that what we call “climate reference areas” need to be established; these areas are closed to all fishing, so that scientists can identify what changes occur naturally as a result of climate change and are not confounded by any impacts from fishing.

Finally, parts of the Antarctic marine ecosystem are globally or regionally unique and need stronger protection. Consequently, MPAs should be established for the protection of key ecosystem processes, habitats and species. CCAMLR has already agreed to do this work but has made no progress since 2016. This work is also a key part of the ecosystem approach to fisheries management.

Conservation requires positive action, especially where research and monitoring data are sparse or even absent.

Q: Is CCAMLR considering any conservation measures that could help prevent negative impacts to penguins, whales and other krill predators?

Courtesy of Phil Trathan

A: Antarctic krill is one of the most abundant multicellular organisms on the planet, with the largest biomass of any wild free-living species – somewhere in the range of 340 million to 540 million tonnes, probably greater even than the biomass of humans. The genome of Antarctic krill also reveals that the species has existed for millennia and has undergone environmental adaptation over geological timescales. Harvesting krill should therefore be feasible, if sufficiently well managed.

A key issue is where and when krill trawlers are allowed to operate, which in turn needs to be based on an understanding of how much krill can be taken from an area that’s also used by krill-eating predators. CCAMLR is legally required to ensure that no long-term damage to the ecosystem should occur as a result of harvesting, and that populations of harvested species and dependent species are maintained at levels that ensure their stable recruitment.

However, identifying how much krill can be harvested from a given area is complex, as krill moves with ocean currents. Consequently, an understanding of regional oceanography is vital, especially if the rate of krill movement doesn’t replace the amount of krill removed by krill trawlers.

Before we can understand the ecological consequences of krill fishing, we need information about krill, about krill predators and about how the environment affects both. That requires long-term scientific research and monitoring, without which krill catch quotas should remain low.

The krill fishery risk assessment approach has gained considerable traction within CCAMLR. Now the work needs to be completed, including research to improve knowledge about where and when penguins, seals, whales and other predators consume krill. In addition to the revised krill fishery management plan, consideration of baleen whales and the need for ecosystem monitoring, recent scientific research suggests that there is an urgent need to implement spatial protection, and that fishing should be prohibited in areas without ecological monitoring.

Q: Your most recent study supports updating krill fishery management in the Antarctic Peninsula in a way that would ensure enough krill are available to all krill predators, especially recovering populations of baleen whales. But at the last CCAMLR meeting, members didn’t reach consensus and didn’t renew one of the management measures that was in place to mitigate concentrated krill fishing in key locations. What steps need to be taken now to put a new, and improved, krill fishing measure in place?

A: Future management requires that CCAMLR agree on a way forward, much as it did with the pilot project for the krill fishery risk assessment and for the other associated parts of the revised krill fishery management plan. CCAMLR endorsed the revised krill fishery management pilot project in 2019 after a number of years of previous work. Now, six years on, it’s time to present the next phase for endorsement to CCAMLR. This will require all members to work collaboratively. Simply saying “no” is not an adequate response and is not part of consensus decision-making.

This next phase should include plans for revising the rules that govern how much catch can be taken and setting catch limits; ensuring that major increases in catch only happen with an incremental staged approach; completing the revised krill fishery management plan; enhancing ecosystem monitoring in winter and summer; agreeing appropriately scaled protected areas; and developing a time schedule detailing how members will work together.

The next phase should be about planning, not implementing. All members must have a shared understanding of what has been agreed upon before presenting the plan to CCAMLR for endorsement; the Scientific Committee must develop the next phase and test to check that there really is agreement on all parts of the proposal.

Otherwise, it will be challenging to reach any agreements about conservation or about resource harvesting. The precautionary principle must remain central as it is a management strategy for dealing with issues of potential harm when scientific knowledge is lacking. The principle prioritizes caution and the need to review evidence before proceeding with actions that might have significant risks. CCAMLR moved backwards during its 2024 meeting, letting its guiding precautionary principle slide. The complex situation that allowed this to happen is deeply regrettable, but it is not yet the end of CCAMLR.

Moving forward, three alternative futures may come to pass. Firstly, CCAMLR will recover its original spirit and work cooperatively. Secondly, no progress will be made, and catches will be constrained by existing agreements. Thirdly, economic pressures will force catches to increase, and CCAMLR may not survive. If the latter happens, then the U.N. might need to become more involved in the management of the Southern Ocean and Antarctica, something many members would not wish to see.

So the future for CCAMLR now lies in how well CCAMLR takes its responsibility for sustainable, precautionary management.

Courtesy of Phil Trathan