Northern Gulf of Evia: end of phase 1

Today we completed our first phase of work in the Northern Gulf of Evia, Greece—a project funded and administered by OceanCare in the context of a collaboration with Tethys.

We did 1,343 km of navigation encompassing the whole Gulf (an area of 1,265 squared km), resulting in 13 encounters with bottlenose dolphins, 3 with monk seals, 5 with large (80+ cm) tuna, 20 with flying fish, and one with a sea turtle.

Giovanni Bearzi and Silvia Bonizzoni

Dolphin and octopus

Today a bottlenose dolphin was making awkward surfacings that attracted our attention.

Initially we though the dolphin was playing with a Cotylorhiza jellyfish—something these animals do from time to time. I took a photo from a distance to find out.

Back at the field station, we did some photo editing and found that it wasn't a jellyfish, but a small octopus. The cephalopod had managed to escape the dolphin's attempt to turn its eigth arms into raw proteins and carbohydrates.

The dolphin was trying to get rid of the octopus attached to its head.

Dolphin pathologies

Living in an area with high inputs of toxic contaminants, and spending much time foraging in polluted waters near appalling industrial plants, it is no surprise that some bottlenose dolphins in the Gulf of Evia show physical deformities suggestive of tumours—such as the one shown in this photo.

Luckily, this dolphin (nicknamed 'Bubbo') still shows a normal behaviour and is often seen socialising with others while moving from fish farm to fish farm.

Above and away

While following a group of dolphins, we look at the sky and see a flock of about 150 grey herons Ardea cinerea with a few great egrets Casmerodius albus.

For a few moments, we forget about the dolphins and get lost in the blue sky as the birds fly above us and away.


Click on photo to enlarge

Dolphins and fish farms

It looks like at least some of the bottlenose dolphins inhabiting the Gulf of Evia have a daily routine that includes spending a few hours foraging near one or more fish farms.

They seem to have become acquainted to human presence, noise, air pollution and dirty water. Apparently, they just care about fish: the wild fish attracted by pellets and nutrients that can be found around the cages.

The dolphins are not afraid of the tangled web of ropes, buoys and cages. They seem to be at home in there, and they engage in occasional socialising.

Industrial dolphins

Bottlenose dolphins surfacing near the smelting plant of Larymna embody the striking contrast pervading the Gulf of Evia: wildlife at its best and human impact at its worst.

Close encounter between dolphin and dolphinfish

In the Northern Gulf of Evia, a lone bottlenose dolphin stops near a piece of white cardboard floating at the surface.

The dolphin shows an awkward 'buoying' behaviour while apparently staring at something below the cardboard (photo). Silvia and I think this may be a weird individual — perhaps with some physical problem? But then the dolphin resumes his normal surfacing behaviour and moves away.

We approach the cardboard and — surprise — we find a 30cm long common dolphinfish Coryphaena hippurus hiding below. These colourful fish often station below floating debris, and later on that day we find others swimming under a wooden box (photo).

Apparently, the dolphin found the dolphinfish and stopped to inspect, possibly while making up his mind on whether that could represent a suitable prey: to eat or not to eat?

No — the dolphinfish was too large to eat, but still a beautiful animal deserving a close scrutiny.

GB

Rain rain...

On a grey October day, we wait for the rain to stop to continue our work at sea.

Stormy weather

Today's dolphin survey attempt in the Gulf of Evia was frustrated by wind and rain.

Smiling again

After 3 monk seal sightings in 3 days, our fourth day of research in the Gulf of Evia finally offered a bottlenose dolphin group.

The animals were found after eight hours of nonstop search, when it felt like there were no cetaceans anywhere.

A few jumps, and we were smiling again :-)

Silvia Bonizzoni

Monk seal # 2

Second encounter with a monk seal in the Gulf of Evia (see previous post). This animal was observed for an hour engaging in food search in a murky bay, not far from an industrial plant. She performed dives approximately 4-6 min long followed by about 30 sec of ventilations. During those 30 sec spent at the surface we could watch the seal in all her beauty while she was elegantly swimming, staring at us from time to time (photo). While she did not seem exceedingly wary of the boat, she never came closer than 30-50 m. This is a wise behaviour, considering that monk seals in the coastal waters of Greece are still sometimes seen as vermin, and shot.

Giovanni Bearzi

Monk seal lunch

Our first day of work in the Gulf of Evia did not have dolphins to offer, but an amazing and unexpected encounter with a monk seal who was having lunch at the surface. The seal had a large octopus in his mouth and he was forcefully and repeatedly shaking it with the head out of the water, producing splashes that could be seen from far away. We speculated he intended to kill the octopus before eating it. We approached at slow speed up to about 50 m to observe this unusual behaviour, and the monk seal did not appear disturbed. He finished his lunch, gazed at us, then moved away. We managed to capture some phases of the octopus lunch, but most photos were blurry due to the distance, except for the one shown here, which even when magnified was sharp enough to capture the fierce look of this large and critically endangered marine mammal.

Giovanni Bearzi

A new dolphin investigation begins

We started a new investigation in the Northern Gulf of Evia (click on image to zoom out).

After having spent a part of the summer dealing with all the logistical aspects, Silvia and I finally moved to a convenient location in the central part of the Gulf. We set up a new field station and managed to get appropriate mooring facilities. We are now ready for work at sea.

OceanCare kindly provided funding to start this new enterprise, and lent a new 100HP engine. Work in the Gulf—done in the context of a collaboration between Tethys and OceanCare—should be conducted between autumn 2010 and spring 2011. Depending on the results, we will decide how the project may unfold in future years.

Some information on dolphins in the Northern and Southern Gulfs of Evia was produced in 2003 by researchers Zafiropoulos and Merlini (*), who reported a high density of bottlenose dolphins in the Northern Gulf. Since then, however, no systematic research was conducted.

Our new study intends to complement the existing information and if possible contribute a preliminary estimate of dolphin abundance, as well as information about status and threats, which may support management action.

The work is also intended to provide insight on dolphin ecology and behaviour in different habitats. It is an exciting opportunity to get to know more about dolphins living in the coastal waters of Greece and allow for comparisons among areas exposed to a variety of human impacts, based on work that is now being conducted in four study areas (the other three being the Amvrakikos Gulf, the Inner Ionian Sea archipelago and the Gulf of Corinth).

Giovanni Bearzi and Silvia Bonizzoni

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(*) Zafiropoulos D., Merlini L. 2003. A comparative ecological study of bottlenose dolphins (Tursiops truncatus) in South and North Evoikos Gulfs. 8th International Conference on Environmental Science and Technology, Lemnos island, Greece.