3 November, 2025 We started our day bright and early and were on the zodiac by 8:30am to get our field-based data collected. We collected hydrophone recordings at four different locations around the Aitcho Islands at the north entrance of the English Strait between Greenwich Island and Robert Island. We had beautiful weather and conditions for a zodiac excursion with an overcast sky, minimal wind, and the temperature around -4°C.
Our first sampling site in a small bay on the northwest side of Robert Island had perfect conditions for recording with minimal waves and crystal clear water, clear enough to see the pebbles and a gentoo penguin swimming around and below the zodiac. While we were waiting for Caroline to collect her glacier data, we saw a Weddell seal surface about 200m from the zodiac. We decided to quickly drop the hydrophone in to record and were treated to a variety of very clear, close vocalizations. After recording for 20 minutes, we travelled to a further location in the central channel between islands, but the wind had picked up so we were getting a lot of surface water sound and more vocalizations from the same seal, just more distant. We travelled to a few different locations but found it difficult to find areas around the islands where we could avoid vessel noise from the Charcot. After two more recordings without any vocalizations we concluded recordings and instead scanned the beaches of the islands for seabirds and seals. We saw snowy sheathbills (the only terrestrial bird endemic to continental Antarctica), chinstrap penguins, gentoo penguins, kelp gulls, imperial shags, a juvenile northern giant petrel, and Antarctic terns.
After 2.5 hours on the zodiac, we returned to the ship for lunch and were quickly informed that we were travelling back to the southwest side of Greenwich Island to Yankee Harbor for more guest excursions and thus another zodiac trip for us. We were back on the zodiac at 3:30pm for a couple of hours of data collection. While at another glacier, noticed a longe gentoo penguin before we saw a Weddell seal near it on shore. A short while later another Weddell seal surfaced near the seal on land before slipping away into the water, never to be seen again. We dropped the hydrophone in and captured another great variety of Weddell seal vocalizations. Due to the size of the bay we were sampling in, we were a short distance (~1km) from where guests were being shuttled to shore so we captured a lot of zodiac noise in the background. While we were sampling a dark cloud had formed to the south and winds started to pick up, but in an effort to record further from the zodiacs we attempted one more recording in the McFarlane Strait. Instead we had vessel noise from the Charcot but we couldn’t go any further away as visibility was declining rapidly and it was beginning to snow. After recording for 5 minutes we decided to turn in, and wisely so. As soon as we headed in a snow flurry quickly engulfed us and waves became much taller and harsh to navigate.
Once all were onboard, the vessel began heading south to cross the Bransfield Strait toward the peninsula to transit the Antarctic Sound and enter the Weddell Sea in the morning!
