Whale studies 13^th – 19^th January

Visual Observations

The visual observations were hampered at the start of the week by periods of fog, but a group of 12-14 fin whales found us while the James Clark Ross was stopped on station and remained around the ship for over two hours. They frequently approached within a few metres of the ship and appeared very curious about the instruments being lowered over the side. We had several more sightings of fin whales before we headed south again into colder water. We also had our first confirmed sightings of hourglass dolphins. As we headed south, the icebergs got denser and we saw some minke whales and a group of ten killer whales. We also saw fur, crabeater and leopard seals hauled out on the ice. As we headed back north, around the South Orkney’s, the ship often had to push through the ice. When we reached open water again we saw our first southern right whales of the cruise. Up to 20^th January we had completed 76 hours of visual observations and made 58 sightings.

Acoustics

The acoustics team deployed 16 sonobuoys during the week of Jan 13-19th. The buoys were deployed in a variety of environments as we passed through some ice south of the South Orkney Islands, as well as open waters of the Scotia Sea. (The work slowed down on Friday night, however, in order to properly celebrate the birthday of one of the scientists on board). Tuesday, 14 Jan was by far the most exciting day, acoustically speaking. While we were on the station and surrounded by a group of we also made acoustic recordings of fins for about 4 hours. At one point, there were also 5 calls by blue whales that were picked up by the same sonobuoy, amidst all the fin whale noise. These calls provided a bit of excitement for us, since they must be some of the first recordings of blue whales from this part of the world's ocean. And they boosted up everyone's hopes of actually seeing a blue whale during this voyage. For the rest of the week, however, we just picked up an occasional fin whale call and some unidentified noises that could possibly be attributed to humpbacks and some possible minke whale calls.

Whale studies 20^th – 26^th January

Visual Observations

We have encountered relatively low numbers of whales this week during transects in the central Scotia Sea. However, the sightings that we have made started to show a picture of different distribution patterns of different species along the north-south transects. In particular, we had several sightings of minke whales in the pack ice around the South Orkney islands, whereas we have seen very few minke whales in the open sea. We also saw some groups of killer whales on the approach to Signy Island. By the end of the week we had completed 115 hours of visual survey along just over 1000 nautical miles of transect.

During a brief visit to the British Antarctic Survey base at Signy Island we were able to visit Adelie and chinstrap penguin colonies. The beach at Signy is littered with whale bones from when the island was used as a base for commercial whaling and provided a reminder of the tens of thousands of whales that were killed in this area last century.

Acoustics

It has been an exciting week in the whale-listening world here in the Scotia Sea. It all started on Monday with nice recordings of marine mammal whistles. Due to bad weather visual observations unfortunately were not feasible so we were not able to determine what species was making the noises, but based on previous recording of different species, it is possible these were whistles from a Mesoplodon (beaked whale).

We heard fin whale calls on 2 of the total of 17 sonobuoys that were deployed last week. Both of these sonobuoys were deployed on fairly northern segments of our transects, around 56^oS. Blue whales were heard 3 times, there were possible minke and humpback calls, more whistles and some clicks, likely to have been made by killer whales, and several kinds of unknown sounds that are likely to be of biological origin.The most exciting sonobuoy deployment was the last one of the week: as we were on station 6.1 we heard many different species of whale. We heard 2 kinds of blue whale calls: the Antarctic-type call, as well as downsweeps that have been attributed to blue whales around the world. We also heard a plethora of other low-frequency sounds: downsweeps, upsweeps, and pulses, that could have been made by humpbacks, minkes, or also some other baleen whale species.

Whale sightings up until 29^th January

	No. sight	No. indiv
Fin whale	10	23
Sei whale	1	4
Minke whale (ordinary)	5	18
Humpback whale	3	7
Right whale	2	3
Killer whale	3	23
Ziphiidae	3	8
Unidentified dolphin	2	4
Southern bottlenose whale	9	19
Mesoplodon sp.	1	2
'Like ordinary minke whale'	3	9
Peale's dolphin	2	5
'Like southern bottlenose whale'	5	5
Unidentified small whale	4	5
Unidentified large baleen whale	14	28
'Like fin whale'	2	2
'Like cruciger dolphin'	1	2
'Undetermined minke whale'	15	23
'Like minke'	2	3
'Like right whale'	1	2