The sun just dipped below the horizon, but not for long. It will appear again within the next 30 minutes leaving us with the most amazing showing of twilight colours: the sky is lit up in shades of orange, shifting to pink, to purple and then to orange again. I am aboard an Antarctic research vessel studying seals for three months. I was supposed to start my next four-hour shift of seal observations at midnight – but I never left the bridge earlier in the evening when I should have gone to bed. There was no cloud bank on the horizon and no wind blowing outside, and I knew that we would be treated to two hours of vibrant colours lighting up the sky, reflected off the water and fields of ice. Everywhere there are scientists and ships crew striding around, sleep deprived but too afraid to go to bed in case they miss any of this.

But now, my shift is about to start, and I haven’t slept in more than 24 hours. A fellow sealer will come and relieve me at 4am when I have about four hours to sleep before we have a weather briefing at 8am. There we hear if we are flying to do seal counting transects from the helicopter (if the weather is good) or if we are staying on board the ship to continue with ship-based observations (if the weather is bad). We are one month into a three-month summer expedition and this routine will be repeated until we finally leave the sea ice. At the end of the expedition we will have collected roughly 250 hours of observations and 15 flights covering somewhere between 180km² and 350km². To put into perspective the cost of this operation: the running costs of the ship per day is 40,000 NZD and 10,000 NZD per hour of flying: that is more than 10 000 NZD per km². To be fair, this number doesn’t just include our work, there are many other scientific projects running in parallel.

Counting seals in the pack-ice is incredibly expensive, labour intensive, heavily dependent on the weather and many hours of work for relatively little return. Not to mention that the position of the ship (and flights leaving from it) is determined by sea ice concentrations, and other scientific or logistical endeavours. This is why scientists still do not have accurate population estimates for most Antarctic species. For example, the Weddell seal population estimate lies somewhere between 200,000 and one million individuals, and only recently eight new Emperor penguin colonies were discovered, increasing the population size by approximately 10%. Perhaps the most obvious example of vague population estimates is that of the crabeater seal: it is estimated that there are between seven and 30 million crabeater seals. How do you decide on effective conservation and management policies when the population lies somewhere between seven and 30 million individuals?