Nov 23 - Bird Island
Last time we left it, we had just sailed from Grytviken to waving from the members of the King Edward Point Station and started 'swathing', which was explained last week. Bird Island Relief was just simply not on the cards so we headed south in heavy seas. By the evening of the 15th we reached our most southerly latitude since leaving Signy, at 58.5degrees south, and it was here we came to pack ice. After watching the sunset over the ice, along the edge of which were large numbers of Fin Whales, the James Clark Ross turned back north, in the direction of Bird island, still 'swathing' as she went.
The ship had arrived at Bird Island by the early hours of the 17th and was anchored in position, ready to start the relief by 530am. The cargo tender was lifted off the deck at 6am and after loading with the cranes was on its way with a full load to base by 7am. In total the cargo tender was filled 7 times with supplies for the base that day. By 2pm the holds were cleared of Bird Island cargo and it was just a matter of fuel drums to be transferred to the station. They were rolled up the jetty to a temporary holding area prior to more formal storage. Below, though, you can see how some of the residents of the local Fur Seal colony used them to gain a height advantage over their nearest rivals.
As well as the cargo, on board ship were a number of new base staff members ready to see their new home. Due to a number of issues, explained later, this was not necessarily to be the chance to move into their new home quite as yet, though it was a chance to meet all their new colleagues on base. This was also a chance for a few to get a first impression of what their daily routine will come to be, which for some, will be for more than 2 years. The new base members, and a privaleged few off the James Clark Ross, got the opportunity to observe some of the wildlife that Bird Island is truely renowned for.
The second day started with all hands being called at 530am and again consisted of 7 runs of the cargo tender in to shore. The first was with the final run of fuel drums and a further six runs to shore, removing cargo from the recent base rebuild. After a second long day of work by all hands, the tender was finally secured back on deck by 6pm.
The planned third day of relief simply wasn't meant to be. A deterioration in the weather had been forcast for later in the day, but while the cargo tender was being prepared to be lifted into the water at 6am, those on the bridge could see things changing infront of them. The decision was made by the captain that it was unwise to continue, and the ship was forced to head out away from Bird Island before finishing its tasks there. The plan was thus to start more science work doing the Western Core Box. We would have to return later, once the weather had eased, to finish cargo work and make all the appropriate personel transfers necessary, prior to us finally heading elsewhere until we return at the end of the summer.
JR129 - krill tv
Bad weather at Bird Island has provided us with an opportunity to do the second piece of science of the present trip, science cruise JR129 (aka 'The Krill Acoustic Survey')
Krill, shrimp-like creatures, are a major food source for many Antarctic wildlife (e.g. seals, whales, birds, fish, squid, penguins), and form a key link in the Antarctic food web between the primary producers such as phytoplankton (equivalent to grass in the open ocean) and higher predators. Determining the biomass of krill and the factors which affect their distribution will help us to: understand the balance between fishing of krill and fish; develop sustainable fishing quotas; and investigate variations in predator (e.g seals, penguins) and prey (krill) interactions.
We are presently in a survey area just north of Bird Island (west of South Georgia) that has been designated as the Western Core Box. Within this area we sail along a radiator like path, at 10 knots, that has been repeatedly sampled, running the same experiment in the same place, over the last seven years and up to three times a year.
We use acoustic (sound) methods to determine the abundance and distribution of krill as well as other pelagic (open water) animals. That is the JCR has a series of transducers underneath the hull that emit sound waves at different frequencies (38, 120 and 200 kHz), and then listen for reflections of these sound waves from objects within the water. These echoes can tell us the amount of copepods (very small crustaceans), krill (medium sized) and fish (bigger). We use this equipment to look at the animals in the surface 300 m of water.
The data collected will be analysed at BAS headquarters in Cambridge and combined with the previous years to determine any trends in krill abundance and distribution. Obviously the longer the experiment carries on, the clearer the picture we will have as to the biomass in the sea as well as the dominant forces driving this abundance.