Polar bear research scientists Thor Larsen (left; photo via Thor) and Jon Aars (right; photo by Jon Aars/ Norwegian Polar Institute)
Thor Larsen was one of the pioneers of polar bear research. He started his career at the University of Oslo in 1965, worked for the Norwegian Polar Institute from 1972, and was a member of the IUCN (International Union for Conservation of Nature) Polar Bear Specialist Group (PBSG) from 1968 to 1985. Together with other scientists in the PBSG, he actively initiated negotiations that led to the International Agreement on the Conservation of Polar Bears, which was signed in 1973.
Jon Aars is now the head of the Norwegian Polar Institute’s polar bear programme. When he started his position in 2003, he had never seen a polar bear before. He was specialised in population demography and population genetics of voles – small rodents. Jon has been a member of the PBSG since 2003.
Thor, when you started the research on polar bears in Svalbard in 1965, what did you work on?
Thor: I started in 1965, and back then, it was really pioneer days. We didn’t know much about polar bears at all. Do all polar bears belong to one population? Or are there several distinct ones? What are their migration patterns? How many polar bears are there, and what are the populations’ growth and mortality rates? What was the impact of hunting? All those questions were important for polar bear management; should they be managed nationally, or in bilateral/circumpolar cooperation? So, it was then when we started a mark-recapture project to get answers to all these open questions. Because polar bears were still widely hunted back then, we were able to get the tags back from the individuals that were shot by hunters. That’s how we, for example, found out that there is one common population between Svalbard and the Russian archipelago Franz-Josef-Land. Later, we started to do den surveys to look at their reproduction, to obtain estimates of how well the population was doing and how that changed between years.
And what is the main focus of research today, Jon?
Jon: The main focus of my work today is population demographics: how different factors affect reproduction, survival and how many bears there are around. But, whenever we are out in the field working with the bears, we take lots of samples for many different research groups that are, for example, working with ecotoxicology, population genetics and diseases. The field of polar bear research is very wide, and we have interactions with all these research groups. Only the Norwegian Polar Institute gets the mandate from the responsible ministry in Norway to take samples from the polar bears in Svalbard. Every year, we get a list of what should be done in terms of polar bear research in Svalbard, and we have to fulfil these tasks.
Each year, we perform mark-recapture work in April; depending on weather and ice conditions, we typically catch between 70 and 80 bears, and mark some with satellite collars that allow us to track where they move, if they swim, and how active they are. The bears take GPS fixes from satellites, and then send all information as text messages through the iridium satellite system. At the same time, we take samples. For example, blood and hair. Occasionally, we also do additional studies in autumn as, for example, in 2004 and 2015, when we performed population surveys trying to assess how big the Svalbard population of polar bears is.
What was it like to do research then compared to now?
Thor: Back then, there were no satellite collars, and we didn’t use helicopters. When we started to look into denning areas, we did aerial surveys by plane of all east Svalbard in 1972 to find out where those denning areas were. Then, each year until 1985, we spent two months on skis, sleeping in tiny cabins, to perform the den surveys. Because the female bears emerge from their dens spread out over almost two months, between mid March and late April, it is important to survey the hills and mountainsides regularly, and again and again, in order to get best possible quantitative data. Weather permitting, we usually skied around for 10-14 hours every day. For other work, we used small ice-going expedition vessels like the MS Polstjerna, which today can be visited in a museum in Tromsø. For the mark-recapture work, we chased and caught the bears from small boats. We knew much less back then, so we dealt with basic questions that were rather easy to answer with small sample sizes.
Jon: Today, we are mainly using helicopters to locate and capture the bears, and we are getting a lot more bears, so our sample sizes are a lot bigger; we have the advantage of that. Thanks to the work by Thor and others, we have a lot of background knowledge. But also, today’s questions are more difficult to answer – to assess, for example, effects of changes in sea ice on body condition, you need very large sample sizes. There are a lot of alternative methods on the horizon, like use of drones or infrared cameras, but they are all still under development, and we will have to see which ones will be useful and feasible in the future.
What are the biggest knowledge gaps when it comes to polar bears today?
Jon: There is no question whether or not climate change has an effect. But the question is – how big is the effect? How critical is it? How does climate change affect polar bears’ body condition, their reproduction, the entire food chain? And what are the thresholds? What are the critical conditions to not have polar bears anymore? Polar bears are very good in dealing with bad conditions, and can live without food for a long time; but what are the critical values? When can they not cope anymore? You need a lot of data years and big sample sizes to be able to draw sound conclusions.
Thor: One important question, for instance, is how climate change affects their denning behaviour. What happens if the denning areas are not accessible anymore because there is no ice? How do they adapt? What are the costs of finding alternative denning areas? They might be quite far away, and the females would have to spend a lot of days walking or swimming instead of hunting. Also, it might take them quite a while to find such new areas. It is difficult to quantify such effects.
Jon: Also, it is always difficult to say what the total picture looks like. We just get “snapshots” in time and place for populations of those bears we follow and have data on. But how representative are they? What are the local distributions and local effects? The Arctic is very vast, and there are big differences between areas, even between different areas just in Svalbard. For example, if we see a certain effect for the bears we follow in Svalbard, is it the same effect for the entire Barents Sea population? The data often just shows local effects and it is difficult to draw conclusions for the entire population.
Sea ice conditions have been bad from the end of 1990s. Since then, there have been very few good ice years, maybe 3 or 4. This trend has already started in the 70s and 80s, but it wasn’t that drastic then. Since 1992, the data shows some trend that the proportion of females with cubs that were born the same year is decreasing. But if lots of cubs die one year, many more of the females will reproduce the following year, so there is a lagged effect of 1 year. And we still see a lot of variation between years, so they can cope with some bad years. So far, the overall time trend is just about significant, but it will likely become very significant in the years to come.
It is obvious that the overall carrying capacity, i.e. the maximum population size that can be sustained by the environment given the available habitat, food etc., has gone down, but we are not sure if the actual population size at the moment has already reached that carrying capacity.
It is just not as simple to say if there is less sea ice, there are less bears. It is a very complex issue.
Is it easy to get funding for polar bear research?
Jon: No! It is probably easier to get funding than for research on less charismatic species like bumblebees and rats. But our main funding is internal funding from the responsible ministry in Norway, and we also get some significant funding from WWF. We are often offered minor funding, small grants, but usually, we have to decline because this often results in a lot of administrative work that outweighs the positive effects. Polar bear research is very expensive work, and it is very difficult to get bigger grants.
How important is long-term monitoring?
Jon: Very important. We need long-term data to be able to say something about the effects of climate change. There is, for example, very good data for the Western Hudson Bay population; this results in very good scientific publications. You also need to follow the bears all the time. Today, some show some very different behaviour than just some years ago. So, you can’t use data from satellite collars from 15 years ago to try to explain their behaviour today.
What is the current status of the polar bear populations?
Jon: In some Arctic areas, polar bears are doing well. In some other areas, where decline of sea ice habitat has been profound, or where hunting pressure may have been too high, populations have declined.
What are the biggest threats to polar bear populations today?
Jon: The biggest threat is climate change, that is for sure. But the impacts of climate change can differ a lot between areas, so it depends very much on local conditions. Another threat is pollutants, but it is very difficult to quantify their effects. We know that the levels of pollutants that we observe in polar bears have effects on other mammals, but we don’t know how big the effects are on polar bears. It is quite likely that they have some effect on reproduction, but there is no proof yet, and the effect might not be very profound because we don’t see strong patterns in the data that would indicate major effects like, for example, a sudden decline in reproduction. So, pollutants are a potential problem, but it is hard to show demographic effects. The polar bears in Svalbard, for example, seem to be doing ok so far despite very high levels of pollutants. We are, however, afraid of an interaction effect between climate change and pollutants; many pollutants are normally stored in the fat layer, which the bears might increasingly have to use when starved for longer periods due to declining sea ice. Pollutants that are not active when stored in the fat may be harmful to the animals when they are released into the blood stream, by interacting with hormonal processes, for instance.
Besides that, there are no other major threats to the population in Svalbard. For some of the other populations, hunting is an issue, depending on the hunting pressure and how well the populations are doing otherwise. And then there are of course other potential effects from industrial development in the Arctic like, for example, the oil industry and disturbance by tourism.
Thor: When hunting is added to natural mortality, total mortality may exceed the potential population growth rates and thus lead to a population decline. This seems to happen in much of the Canadian Arctic.
Will polar bears be able to adapt to climate change?
Jon: They definitely have some plasticity. Polar bears are very opportunistic, and they always adapt to changing conditions; but I think there are certain thresholds. I don’t think polar bears will be around in areas without sea ice. In most of those areas, brown bears will move in. If that happens, brown bears will be the bosses; polar bears are chicken even though they are bigger!
Thor: What are their learning techniques? For example, there was a population in Newfoundland that was known to catch salmon. However, that local population was eradicated by hunters, and the polar bears coming to that area afterwards didn’t know how to do that. Others have been observed to catch seabirds from underwater or to specialise in preying on walrus. So, they are smart and can learn new techniques. That can help them to adapt.
Jon: Definitely, but as a polar bear, you can’t just live off catching sea birds; it may be a good substitute in times where their main prey, seals, are not available, but it is not enough. And often these hunting techniques also come at high energy costs, so they have to spend a lot of energy to find food. Polar bears have also been observed to eat grass, but that is probably just to fill their stomachs; it does not provide them with much energy. So, I don’t think that in the future we will see polar bears that will live off seabirds and grass; they need seals and for catching seals, they need sea ice.
How old are polar bears as a species?
Jon: Scientists disagree regarding how old polar bears are as a species, but they are probably much older than we thought. Estimates range between 6,00,000 and 4-5 million years. There is also some discussion whether they are even a distinct species, because they can mate with brown bears, and get fertile juveniles.
It has been many million years since the Arctic was last ice-free everywhere. They might just need a small refuge with some ice to potentially survive as a species. It is very likely that they will die out in some areas and survive in others.
The dynamics of climate change and how they impact polar bears are very difficult to predict. There are some areas, and this is something that is not very often portrayed, where the habitat gets even better for polar bears. At the moment, there is less multi-year ice but more single year ice which has more cracks, and thus makes it better habitat for seals. and therefore better hunting grounds for polar bears. So, at least for a transition period, before all ice is gone, these areas offer better conditions; so, impacts of climate change are also very local.
What needs to be done in your view to protect polar bears better? Besides mitigating climate change. What other management measures could help the populations?
Jon: The best and most important measure is climate protection, that is for sure. But, we also need to figure out through which mechanisms climate change affects polar bears, and how these mechanisms work exactly, to see if there are other management measures to help the populations. It might be very different measures that are useful in different areas, for example, protection of denning areas could be useful in some places. But, if you lose most of the sea ice, no other measures will be helpful for a lot of areas.
Do you feel that your research is contributing to a better management of polar bear populations? Is it informing policymaking?
Jon: I think it contributes. The media are so interested in polar bears. The Stockholm Convention on Persistent Organic Pollutants is a great example. There you have a direct link between studies that have shown the impacts of certain pollutants on polar bears and other Arctic species, and politicians deciding to ban these pollutants.
Thor, you were one of the first members of the IUCN polar bear specialist group. What was that like back then? How did the group work? How much influence did it have?
Thor: In the beginning, when the group was established in 1968, it was constituted of two polar bear scientists from each of the five Arctic countries that have polar bears within their range. All members were personally invited by the IUCN, because they wanted to prevent that countries sent delegates that were politically chosen. We all knew each other, and the sessions were closed, so we had very open discussions. Back then, the group had a very active role in voicing concerns about the status of the polar bear populations, and we were actively recommending the IUCN to foster polar bear protection. We were the ones initiating the political talks that led to the International Agreement on the Conservation of Polar Bears in 1973.
Jon, you are a member today. What is the work like today? What do you think it has changed?
Jon: Today, the group has over 30 members, and most are still polar bear scientists. For a while in between, members were appointed by the nations, and they often decided to send managers instead of scientists. But this procedure was changed recently, and now, new members are appointed by the chair of the group. Today, the group is not that pro-active anymore, we are more neutral and just provide information if we are asked. This role was set in the Polar Bear Agreement. We can still voice that we are concerned, but we are not telling governments what to do, we only say what is likely to happen if they do this or that. So, we are not asked to make recommendations; we don’t have a mandate to do that, but we evaluate impacts of certain management measures. For example, we don’t say “We think you should not allow for bears to be hunted,” but, “If you allow for this population to be hunted, we think that the population will decline”. We provide such information based on our best knowledge. The managers then have to decide whether they act according to the information we give them, or alternative information, for example, traditional ecological knowledge. We don’t always give the managers information they agree with. So often, it is “western science” vs. traditional ecological knowledge.
Are the group’s recommendations flavoured by the composition of the group? For example, which position did the group take in the highly controversial question of upgrading polar bears to appendix I under CITES?
Jon: What the group says will, of course, always be flavoured by who is in it. But, if we take the CITES upgrading as example, we were simply asked whether polar bears as species meet the criteria for being listed under appendix I or not. We only have the mandate to answer such questions on a scientific basis, not to make recommendations. So, we got a document, and then a subgroup was established that went through the wording and arguments and checked whether everything was correct or not. Then we sent the document back. So, we provide the scientific background knowledge, but it is managers that decide. But, of course, there is also a difference between what the group says as a body, i.e. our scientific consensus, and what members of the group individually say publicly.
Is the polar bear protection agreement from 1973 still up to date and useful?
Jon: It is an important agreement, and up to today, it is still influential for how a lot of research and management is done. It is important for us scientists because it means that Arctic nations should try to get data relevant for management. So, the treaty has an important mission of supporting polar bear science; a lot of scientific polar bear programmes would not be there today if it wasn’t for the treaty.
How good was the circumpolar cooperation regarding polar bear research and management back then, Thor, and how good is it today, Jon?
Thor: In the beginning, we had heard about each other, but most of us had never met in person. But through the years, there was lots of exchange and bilateral discussions; we joined each other for fieldwork and expeditions and learned a lot from each other. For example, back then, we didn’t know how to best catch a polar bear. So, it was years of intensive learning together, based on personal professional friendships, mutual trust and confidence. It was very fruitful.
Jon: Today, it is still very much the same. We meet quite often and exchange information; we often invite each other between groups, calibrate and exchange methods and try to learn from each other. That goes also for the Russian scientists; there is, for example, good cooperation with them regarding the population surveys of the Barents Sea population.
What fascinates you about polar bears?
Jon: I am fascinated by most mammals I work with and ecological questions. Polar bears are very large and powerful, so certainly a very special mammal. You don’t get bored of them. And I think, a lot of the fascination for polar bears comes from the fact that they live in an environment that you don’t feel comfortable with yourself, and this mix that they are, very “cute” but also very dangerous.
Thor: I feel very fortunate that I got to work with one of the “glamorous” animal species. They are beautiful, majestic and very fascinating. For me, it has been a love affair; I have a lot of respect for these animals, and even after more than 2000 encounters, they are still as beautiful and fascinating as the first time. They are the symbol of the Arctic.