Archipelagos Marine Mammal Research team took part in a very interesting boat survey in the region of the Trench in the north of Ikaria island. This is a very rich biodiversity hotspot reaching 1400m depth, where there are still a lot of knowledge gaps to cover. This expedition, under ideal weather conditions allowed us to increase our knowledge and understanding of this area and catalogue species that are rarely sighted. Among others we recorded the migration of 2 male sperm whales (Physeter macrocephalus), as well as 5 dolphin pods, including Bottlenose (Tursiops truncatus) and Common (Delphinus delphis) dolphins, while we also had a very interesting behavioural observation of a Mediterranean monk seal while feeding.
We were all very enthusiastic about the idea of spending days on the boat and exploring the Trench because we knew that the species in this area are very special and any data collected is of great value. During the boat surveys, interns participated in data collection and also had the opportunity to listen to live recordings of dolphins’ clicks and whistles and Sperm whales’ clicks. These data are critical to provide a better understanding in this important marine area.
We left the Archipelagos Base located close to Pythagorio in Samos at 7:30am and commenced our survey with the sailing boat Pinelopi at 8:00 am. During boat surveys, several types of data were continuously collected. The marine mammal team members collect data regarding environmental conditions, marine litter, bioacoustics and noise pollution, as well as seabirds. When a sighting occurs, photographic data with cameras and a video camera were recorded. Moreover acoustic and behavioural data were collected with the help of a hydrophone and data sheet notations. After leaving the port we surveyed the marine area south of Samos and reached to the north of Samos following the north coastline of the island and then heading towards the northern part of Ikaria, where we found ourselves over the deep water area. Our first two sightings appeared in the morning close to Samos. Both times we identified the Common bottlenose dolphin (Tursiops truncatus). Our team was well prepared and we worked well together, managing to collect great pictures for our Photo ID catalogue as well as behavioural notations.
Once approaching the Trench we detected Sperm whale clicks pretty quickly. After almost two hours one of us managed to spot the whale. The sighting was very short but also intense. We got to see it close enough to collect the data we were so desperately hoping for before it dived into the deep again after logging for about ten minutes at the surface. After heading to the port Aigos Kyrikos located in the south of Ikaria, we ended a successful boat survey day with tears of joy and a clear goal for the next day: Locating the sperm whale again and collecting more data!
Our second boat survey day started with great weather conditions. We found the sea calm, allowing us to spot marine mammals more easily. After leaving the port of Agios Kirikos early in the morning we headed back to the Trench. On our way there we had two dolphin sightings – One bottlenose (Tursiops truncatus) and one short-beaked common dolphin (Delphinus delphis) sighting.
We recorded some great acoustics with the hydrophone and eventually detected sperm whale clicks again. After spending the whole day in the Trench, we went back to the Ikarian port very satisfied since we had three Sperm whale sightings with two individuals. We were able to identify them by the characteristics of their tail with the help of the pictures we took for Photo ID. One of them was the whale we had spotted the day before while one other was also recorded in the same area several years ago. It felt great having achieved this and therefore being able to provide data for Archipelagos’ conservation efforts.
On the third day, we left Ikaria port at 8:00 am to finally return to the Archipelagos Base in Pythagorio. We started our trip in stormy conditions with rain, wind, and thunder, so we could not collect data. It reminded us that the research at sea relies entirely on weather conditions that we have no control over. However, the weather improved, so we were able to start surveying again. We had two sightings of Bottlenose dolphins (Tursiops truncatus) with one of them located next to a trawler, so we could collect very interesting behavioural data of dolphins feeding and socialising with their calves under anthropogenic influence.
We all thought that the day was already over with the two great sightings, but it was without knowing what amazing last sighting was waiting for us. Indeed, one intern spotted a Monk seal (Monachus monachus) in an area where the species had already been spotted a few times before. The Monk seal was feeding on an octopus, which he threw in the air to kill its prey. Since the species is considered “Endangered” and one of the species most at risk of extinction by the IUCN Red List, we were amazed by this last sighting.
We headed back to Pythagorio port at 4:00 pm and in the coming days we worked on the report of the data collected, as well as the various data analyses.
The crew on board was comprised of two marine mammal researchers Beatriz and Andrea, our Captain Periklis and a group of interns from different countries. We all worked very hard
together and in good coordination and collected some great data. Having the opportunity to see these majestic animals is breathtaking, while being able to share our passion but also
our common responsibility for their protection with other people from all over the world is very fulfilling and inspiring