We had an eventful weekend on the LMG, visiting a British research station on Adelaide Island on Saturday and nearby Avian Island on Sunday. We arrived at Rothera Station early Saturday morning and traded most of our LTER team for a group of British scientists. The British base was very welcoming and had a full of day of crevassing, skiing, hiking and boating activities planned for us. Meanwhile, their scientists took advantage of the use of our ship for a few offshore science projects.
We “whalers” took advantage of the free time and good weather and spent the morning looking for Minke, Humpback and killer whales in the vicinity of Rothera. We had hoped to put a stop to our long streak of days without whales but unfortunately there were no whales to be seen. Despite this, we had a great morning taking photos of the many icebergs, leopard seals, Wilson’s storm petrels and blue-eyed shags in the area.
Sunday was a beautiful bluebird day and we had a gorgeous transit from Rothera around the south end of Adelaide Island to Avian Island. We left two of our LTER colleagues on Avian and they will be camping there for the week. They will be studying the island’s population of Adelie penguins, conducting diet studies and assessing reproductive success by weighing, measuring and counting Adelie chicks.
Spending a week each year on Avian Island is an important aspect the seabird component of the LTER program because Avian Island serves as a sort of “control” study site, to compare to the more rapidly changing Palmer site. The differing physical and biological conditions at each of these two sites allow scientists to assess how things like local sea-ice conditions and biological productivity affect each of the local penguin populations. There are around 80,000 Adelie penguins on Avian, so you can imagine that we could smell the krill-colored guano long before we landed on the island.
The last three days have been pretty tough. We had not seen any whales since the 20th. The weather has been pretty unforgiving, and the winds have pushed a lot of ice in the inlet making it hard to get the zodiacs away from the pier. The weather finally let up today and we were fortunate to travel within the extended boating limits with the bird group to dream island and Biscoe bay.
We sampled three whales today, but probably seen some where around half a dozen in total. The many icebergs within the boating limits make it hard to follow and see the whales at distance. We have collected 13 biopsy samples thus far. So far it has been a pretty slow year. We also had two Adélie penguins jump into our boat today while we were sampling.
We photographed one whale, presumed female because it was accompanied by a juvenile, which had intense scarring on the left side near the dorsal. We are unsure what may have caused it, but it looks as if it is from a potential fishery line interaction. We have yet to have a re-sight within the palmer boating limits, which is a sign that the whales are moving in and out of the area quite rapidly. This is good for us, as it means we will get a sample from a wider range of individuals.
The weather is supposed to be good for the next couple day so hopefully we will be able to get some more echo sounder surveys in and look for krill biomass, and of course get some more whale samples. We were able to see some large mountains today as the sky began to open up.
We learn a huge amount about the humpback whales we study from tiny samples of skin and underlying blubber. We use a specially designed remote biopsy dart system, which we fire from a crossbow, to obtain a tiny sample from each whale we identify in the field.
Each sample measures about 25 mm in length and 5 mm in diameter and weighs only a few grams. In contrast, the whales are about 15 meters long and weigh 40 to 50 tons. The best analogy we can think of is that it’s like a mosquito bite to you or me.
We work hard to ensure that we identify each whale before attempting to sample it. We try to not resample an individual within a field season. We do this by comparing pictures of an animal’s fluke, which is unique to the individual, with our current biopsy/fluke catalog, which is stored on an iPad that we bring onboard. We are able to utilize the pigmentation and scarring of the flukes to identify individuals. If the whale is new to us, we move our Zodiac alongside the whale and fire the biopsy dart at its flank when it arches to dive, usually from a distance of 10 or 15 meters. We are extremely careful throughout the entire sampling process as to not get ahead of the whale or get directly behind its fluke. So far Doug is an excellent driver, and if not for today, I would have a 90% shooting rate, but now am sitting back down around 50%.
The tiny samples provide an enormous amount of information about each whale we sample, including its sex, recent dietary history, reproductive status, and health. We also use genetic markers to infer which breeding population the whale comes from.
Part of my master’s work will be to conduct progesterone assays on the blubber from our samples to determine if female whales are pregnant. We have successfully now documented variations in pregnancy in our samples from 2010, 13, and 14. We are really excited to look at 2015 and this year’s samples over the summer.