Marine Mammals & Sea Turtles

Observing & Monitoring



The North-Eastern Aegean Sea hosts some of the most important remaining marine mammal and sea turtle populations, constituting a key area within the Mediterranean Sea - there are at least 11 cetacean species that regularly occur there. One of these is the Fin whale (Balaenoptera physalus), the only Misticeti and the biggest cetacean present in the Mediterranean Sea. The other 8 species are Odontoceti, a parvorder of cetaceans that includes: Common Bottlenose dolphin (Tursiops trucatus), Common dolphin (Delphinus delphis), Striped dolphin (Stenella coeruleoalba), Risso's dolphin (Grampus griseus), Cuvier's beaked whale(Ziphius cavirostris), Sperm whale (Physeter macrocephalus), long-finned Pilot whale (Globicaphala melas) and the Harbor porpoise (Phocena phocena). While some of these species are defined as regular (Common Bottlenose dolphin, Common dolphin, Striped dolphin, Risso’s dolphin, Fin whale, Sperm whale, long-finned Pilot whale), the Harbor porpoise is classified as a rare species as its presence is only recorded in the north of the Aegean Sea. This part of the Aegean Sea is also host to the Mediterranean monk seal (Monachus monachus), one of the most critically endangered marine mammals in the world, and three species of sea turtles: the Loggerhead sea turtle (Caretta caretta), the Green sea turtle (Chelonia midas) and the Leatherback sea turtle (Dermochelys coriacea).

Cetaceans, pinnipeds and sea turtles encounter various threats to their status. The most serious threats to cetacean populations in the Eastern Mediterranean Sea were identified as: interaction with fisheries, disturbance, injuries and mortality from shipping, habitat loss and degradation (including chemical pollution), anthropogenic noise, direct killing and live capture (e.g. bycatch, entanglement in driftnet) and climate and ecosystem change including potential effects on prey availability.

Even though there are various national and international commissions and agreements to protect these species, there are no effective and sustainable conservation measures for cetaceans in the Aegean Sea. As a result, several of these species are considered at risk with a lack of effective conservation actions.



In Greece, with over 18,000 km of coastline and a sea surface area of approximately 220,000 km², the collection of data regarding the populations and strandings of marine mammals and turtles is extremely difficult. The research carried out on these species is limited, and unfortunately, strandings are rarely reported.

Since the beginning of its operation, Archipelagos’ research has focused on the assessment of marine mammal populations. Currently taking place in the Aegean region, the Archipelagos’ research and conservation work aims to fill the basic knowledge gaps and to broaden the knowledge on the least studied populations of rare and endangered species.



Archipelagos works in cooperation with international organisations dedicated to the protection marine mammals and turtles.


The Aegean Sea region hosts an exceptional biodiversity.  Marine mammals and sea turtles are top predators in the food chain, but most of them live in precarious conditions as a result of intense anthropic presence. Human activities are often a  source of a variety of pressures that threatens the survival of these animals, classifying them as at risk by the IUCN (the International Union for Conservation of Nature).


The Marine mammal research of Archipelagos Institute aims to monitor the regional status of marine mammal populations and habitats in the North East Mediterranean basin, a key habitat for several cetacean species and where the data about the status of these species are largely lacking.
With better knowledge on their populations and the factors threatening them, we aim to identify critical habitats and to limit the major environmental impacts. Finally, to propose effective and sustainable conservation measures, we aim to combine research with public awareness campaigns.

The project are focused on the following fields:

  1. Cetacean presence, abundance and distribution studies by boat and land based surveys
  2. Studies of cetacean behavior and behavioral changes under the anthropogenic activities
  3. Ferry fixed-transect monitoring of cetaceans
  4. Analysis of the environmental factors influence on the distribution and abundance of cetacean
  5. Movement pattern, residency pattern and social structure through mark recapture photo-identification techniques
  6. Archipelagos Stranding Response Network
  7. Monitoring of the Mediterranean Monk Seals (Monachus monachus) and Sea turtles
  8. Microplastic/Macroplastic: marine debris monitoring and assessment on shore
  9. Eco-navigation: a guide for sailors and sea enthusiasts to report their observations in a citizen science database
  10. Aegean Marine Life Sanctuary: the creation of a multi-purpose center in Greece for the rehabilitation of stranded marine biodiversity and dolphins from the captivity
  11. Citizen science and School education and awareness projects
  12. Video and photo of Cetaceans for conservation campaign projects
  13. Assessing fish biomass estimates by a multi-beam sonar
  14. Bioacoustics monitoring and recording of the communication of cetacean species

Cetacean presence, abundance and distribution studies by boat based and land based surveys

Knowledge on abundance, trends and distribution of cetacean population is needed to increase marine conservation efforts, ecosystem models and spatial planning. Land based and visual line-transect surveys, conducted along pre-defined track lines, on ships with dedicated observers, are a couple of the most widely used methods to quantify cetacean occurrence and density over a large area.

Archipelagos’ is conducting distribution and abundance studies focusing on how species are spatial, temporal and taxonomical dispersed in the North Aegean Sea. Using pre-determined transect lines during boat surveys, it is possible to increase the accuracy of abundance and distribution estimation of cetaceans. The distribution of a species is affected by different biotic and abiotic factors. Therefore, our study is focused on the spatial modelling of habitats using environmental data to explain the distributions and predict areas of importance. Information provided can be used to update the regional conservation measures.

Distribution patterns is specie-specific, it can change seasonally in response to availability of resources, and behavioral needs. Combining the data collected in boat and land surveys, we are able to map the presence of each species. Distribution maps are created on a monthly, seasonal and yearly basis to have a complete representation of distribution variation. Using these maps, we can investigate if there is any overlap with area usage as well as exploring the negative effects of anthropogenic activities on cetacean life and habitats.

Studies of Cetacean behavior and behavioural changes under the anthropogenic activities

Behavioral analysis results using BORIS

Archipelagos’ behavioral study is focused on the analysis of a specific ethogram for a target species. The behavioral data collected during surveys are analysed statistically using innovative methods and software. The aim of this study is to identify how the anthropogenic activities can affect the life of marine mammals and to map important habitats, for example those used for feeding, resting and nursing. Altogether, this data will help us implement effective conservation measures and management strategies to avoid impending population decline.

Ferry fixed-transect monitoring of Cetacean and litter

Transect map including Samos and the surrounding Islands

Archipelagos’ members use the Ferry cruise from Samos to Lipsoi and return to gather more data about cetaceans. As the Ferry carries out its tour on the same days and times during the week, we can take this consistency to our advantage. Similar to our boat surveys, environmental as well as sighting data is collected.

Assessing fish biomass estimates by a multi-beam sonar

Fish location, identification and measurement as well as seabed profile surveying are a useful help for the research on cetacean distribution. A multi-beam technology can identify the area of the cetacean's prey in order to get also more acknowledgement about their behavior.

Encounter rates of Delphinus delphis in the study area (b) Encounter rates of Tursiops truncatus in the study area, Feb-June 2017

Analysis of the environmental factors influence on the distribution and abundance of Cetaceans

Environmental factors in sea water (sea surface temperature, temperature-depth profile, surface salinity, oxygen concentration, depth and pH) can affect distribution and correlation of cetaceans. Environmental analysis were carried out to understand the possible correlation with the occurrence of Delphinus delphis and Tursiops truncatus as well as their habitat preference along the southern coast of Samos Island and its surroundings.

Movement pattern, residency pattern and social structure through mark recapture photo-identification techniques

Archipelagos’ population study is focused on the presence of specific pods in certain study areas. A Photo-ID mark-recapture method is applied to identify individuals and to investigate movement patterns, residency patterns and social structure. Thanks to this method, it is possible to have a complete census of the presence of a population in a specific area helping to create a Photo-ID catalogue for each year. When it is not possible, a population study as well as a Photo-ID study could be used for a predictive estimation/evaluation of the density of the population, showing their resiliency to anthropogenic impacts. The photo identification study represents an effective help for implementing the protected area.

Numerous individuals have been identified within recent years: 2015, 2016 and 2017. Among these dolphins, several have been proven to return to the area. New data is collected on a weekly basis and is used to track residency patterns as well as habitat preference and social structure.


Aegean Marine Life Sanctuary: the creation of a multi-purpose center in Greece for the rehabilitation of stranded marine biodiversity and dolphins from the captivity

The Aegean Marine Life Sanctuary aims to be the first refuge in the world providing a solution for the long term retirement of formerly captive dolphins. It will set the standards for rehabilitation in semi-natural conditions, giving the dolphins the opportunity to re-learn their innate natural behavior, such as hunting for live fish. To read more click HERE

Archipelagos Stranding Response Network

Over the last decade, the Archipelagos Stranding Response Network has been developed with the cooperation of Archipelagos’ researchers and volunteers, as well as local communities of the Aegean Islands. This network is dedicated to providing first aid and rescue in incidents of live stranding, entanglements and entrapment. When a stranding event is reported, the Archipelagos’ team intervenes, depending of the case, to rescue or to conduct a necropsy collecting samples for further analysis.

Monitoring of the Mediterranean Monk Seals (Monachus monachus)

As the Eastern Aegean region supports important populations of Mediterranean Monk Seal, in parallel to cetacean research, Archipelagos is also carrying out research on this important endangered species. The interactions with the fishing communities, as well as other threats, have to be monitored in order to develop and enforce realistic conservation schemes that are urgently needed for the protection of this rare marine mammal.

Microplastic/Macroplastic: marine debris monitoring and assessment on shore

The Archipelagos Microplastics Team is working on the dissection of cetacean and sea turtle species found in stranding around Samos Island, Greece. The analysis of the gastrointestinal tracts of each marine animal is conducted in order to quantify the microplastic particles and to understand how this global problem is affecting these species.

The Macroplastic project primarily focuses on measuring the influx of waste items into the Aegean Sea onto specified beaches at the main Archipelagos Base. Human activity has a significant impact on the health of both marine and terrestrial ecosystems. Archipelagos has completed daily beach cleans on two Samos local beaches aiming to pick up as many identifiable forms of macroplastics as possible.  All debris were analysed and cataloged into data sets to establish a pattern of macroplastics and other debris found in accordance with the health of marine ecosystems.

The project also aims to increase public awareness about the detrimental effects of littering on beaches and aims to increase awareness on a wider scale.

Eco-navigation: a guide for sailors and sea enthusiasts to report their observations in a citizen science database

Archipelagos’ Eco-navigation project focuses on creating a citizen-science platform about observations of marine mammals (dolphins, whales, seals), sea turtles, invasive species and jellyfish blooms, as well as pollution incidents (plastic debris, oil slicks, etc.) or other unusual sightings. In this way, we are in the process of forming a network of sailors, divers, fishermen and sea enthusiasts who will contribute to the Eco-Navigation network providing information and photographs of the observations they make at sea. The aim of this project is to create an online community and a database concerning the status of the Greek and the whole Mediterranean Sea from observations of sailors and sea enthusiasts.

Citizen science and School education and awareness projects

The Archipelagos’ team is active in various parts of the Aegean region, involving and engaging the island communities in its research and conservation efforts.  A wide variety of media material is produced to raise awareness, including leaflets, posters, booklets, children’s fairy tales, educational games and DVDs. Various events to raise awareness, such as workshops and conferences, also take place in island schools and communities throughout the year. For Archipelagos, this important investment is the key to long-term protection of the Greek seas and the entire Eastern Mediterranean.

Video and photo of Cetaceans for conservation campaign projects

Video and photography footage of wildlife ensure the documentation of studied animals. This data collection is essential not only for developing a variety of awareness campaigns but furthermore to get results for scientific studies.

Bioacoustics monitoring and recording of the communication of cetacean species

Bioacoustics is a multi-disciplinary science that combines biology and acoustics, thus referring to the investigation of sound production, dispersion and reception in animals.

The Marine Mammal Team bioacoustics research aims to estimate the noise level and to record the cetacean species calls in different areas of the Aegean Sea. The objective aspires to show a direct correlation between the difference in cetacean communication sounds and the increase in marine traffic in the waters around Samos using bioacoustics.


Deliberate Killing, Bycatch and Ship Strikes

Although much rarer in comparison to previous times, intentional killing of cetaceans is still a big issue in the Mediterranean, even though cetaceans are protected by environmental law, which makes killing them illegal. The mission of Archipelagos is to record these deliberate killing incidences in an official database and to take action towards their prevention. Efforts are also being directed towards the prevention of bycatch – the incidental mortality in fishing gear. Lost and/or drifting nets may be ingested by cetaceans and lead to serious harm. Another important matter being considered is the increasingly frequent ship strikes, especially of large cetacean species.

Depredation and Fishing Gear Damage

Some species of cetacean (e.g. common bottlenose dolphin) may show a particular preference towards taking advantage of feeding from fishing nets, potentially causing catch loss or gear damage. Archipelagos is constantly working to evaluate the magnitude of this problem, in order to determine the extent of interactions, and to try to find solutions for when depredation causes real problems, such as economic losses. Cetaceans also interact with aquaculture structures that tend to have prey concentrate around them.

Prey Depletion and Illegal Fishery Disturbance

Overfishing or destructive fishing can have devastating consequences on marine ecosystems and cetacean presence. Illegal fishery activities can be extremely destructive to the surrounding ecosystem, for example, the use of blast fishing often destroys the underlying habitat.

Habitat Degradation

There are many factors which affect the loss of habitat, most of them are related to anthropic activities such as mechanical and chemical pollution e.g. dredging, anchoring, trawling, urbanisation etc. Poor habitat quality decreases its attractiveness to cetaceans, endangering important, strategic areas e.g. areas related to feeding, foraging, nursing, breeding, migration, socializing, resting, etc.

Chemical Pollution

The chemical pollution affects the entire marine trophic chain, so it is considered a serious problem for the marine environment. Cetaceans, being long-living, top predators, accumulate high concentrations of toxic substances in their tissue (bioaccumulation and biomagnification), making them vulnerable to health problems (e.g. hormonal disruption, immune suppression, reproductive inability, etc.).

Noise Pollution

Anthropic activities are responsible for an increase of underwater background noise. Underwater noise is considered one of the most serious threats to cetaceans worldwide, as well as being one of the most difficult ones to address properly. Marine traffic, military activities, seismic exploration, oil and wind farm activities etc. can cause disturbance, discomfort, stress, harm to hearing, injury and death, while also masking biologically important sounds that are necessary for hunting prey.

Global Climate Change

Cetaceans are facing increasingly severe threats from climate change. This change may impact the areas in which they live and including their migration patterns. Global warming, and the depletion of the ozone layer resulting in a rise of UV radiation, may also affect the population of krill, a primary food source for many marine species. Even if cetaceans have some capacity to adapt to changing environment, climate change is now developing at such a fast pace that many populations could be at great risk.

Basic First Aid



Marine animal stranding (cetaceans, seals and sea turtles) are phenomena in which one or more animals are found, alive or dead, floating in the sea or stranded on land, usually on a beach shore, or in shallow water. Saving live animals isn't as easy as it looks, and if you don't know what you're doing you can sometimes do more harm than good.

The first thing to do is to report any stranding event as soon as you discover it. In any case, the main priority is to avoid causing more stress to the animal, as this is a common cause of death. Furthermore, moving a stranded animal to deeper water is also one of the main causes of death.

Only trained experts with many years of experience can successfully manage a live stranding or conduct a complete post-mortem analysis of the event, in order to study the complex and multifactorial causes of death, useful for the conservation of the species.

What should you do upon discovering a stranded marine mammal or turtle?

  1. Please note the place, the state of the tide and any injuries you can see without getting too close, call port police and the Archipelagos team. We will then advise you on what to do and will get a trained professional/medic out ASAP.
  • Port Police (Vathi) +30 227 3027318
  • Archipelagos Research Base: +30 227 3061191
  • For urgent matters ONLY: +30 697 4744949
  1. Avoid sudden and unnecessary movements, loud noises, close examinations and large crowds of people surrounding the animal.
  2. Check for movement from a distance. It might be normal for a turtle or a seal to stay on a beach; therefore they may not be stranded.
  3. Do not approach or touch the animal. Marine animals can carry infectious diseases that can be transmitted to humans with zoonotic implications and vice versa.
  4. After being in contact with an expert, following their instructions, keep the animal cool and wet, provide shade for the animal and ensure that the blowhole/nostrils are not covered and are clear of water and debris.

Archipelagos provides first aid training to ensure that trained volunteers that can respond to stranding in an efficient and effective manner are present in different regions of Greece. For more information about our first aid training, please contact us.

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