Research on cetaceans in Catalonia – Interview to Cetàcea Association

I had long wanted to do an interview with Associació Cetàcea, an association of Catalonia (Spain) dedicated to the study of the dolphins and whales that inhabit the Catalan sea. This association, founded in August 2012, has recently published the results of its photo-identification study.


Hello, how are you? Before beginning to talk about the results of your study on cetaceans, explain to us what Associació Cetàcea is. For what purpose did it come?

Associació Cetàcea is a non-profit organization whose main objectives are to increase the knowledge we have about the cetacean communities that frequent the central Catalan coast and to promote their conservation and the habitats in which they live. Another goal of the association is to bring this knowledge to any interested person, with the ultimate intention of raising awareness about the importance of protecting marine ecosystems.

Now, let’s start talking about your study, which focuses on the Garraf coast. Why this area and not another?

When we started the project in 2013 we knew that on the coast of Garraf, it can be seen cetaceans, especially whales during the spring. Looking for bibliographic information, we realised that there was not much. It was then that we decided to start the current study, focusing first on the fin whale, and extending it to other species later.

The map  shows the location of the study zone of Associació Cetàcea (Picture: Google Maps).

Our initial intention was to know which cetacean communities frequent this area, what distribution they present and whether they can be considered resident or not. In addition, we were also concerned about the proximity of the harbour of Barcelona, ​​with an intense commercial maritime traffic, and what effect it could have on the different species.

There are many different ways to study cetaceans, but you have been studying them since 2014 by photo-identification. Can you explain what this method of study consists of?

Photo-identification is a non-invasive research technique that consists of photographing the individual identification characteristics of each of the animals in order to be able to recognise them throughout their life. These features of individual identification must meet three requirements to be used for the recognition of individuals. First, they must be permanent, that is, they do not disappear with the passage of time; must be unique, that is, not repeated in more than one individual; and, finally, must have the same likelihood of re-viewing.

And in cetaceans, which are almost always under the water, how does it apply?

Because of cetaceans are marine species and spend most of their time underwater, individual identification marks must be located on parts of the body that can be observed from outside the water. In fact, these features vary from one species to another, and are located in areas as varied as the head, dorsal fin or caudal fin of the individuals. In our case, we used this technique to study the bottlenose dolphin, the Risso’s dolphin and the fin whale. In all three species, we use the dorsal fin and the wounds of its posterior margin as main characteristics of identification, since they are maintained in the time. In addition, we also use wounds on the sides of the dorsal fin and other parts of the body as a secondary mechanism of identification, which is very useful especially when comparing photographs of the same sighting or the same year.

The use of this technique has allowed us to create two catalogues of photo-identification, one focused on the bottlenose dolphin and the other on the Risso’s dolphin. We are currently working on the creation of a third catalogue for the finwhale.

I imagine you take hundreds of pictures in just one trip. What is required for a photograph to be included in the catalogues of the species?

You’re right, at each trip we can get hundreds of pictures. The arrival of digital cameras and, above all, the progressive increase of their storage capacity offers us the possibility of making as many photographs as we want in each one of the sightings. We have come to realise between one and two thousand photographs only of a single trip.

associació cetàcea, cetacis, catalunya
One of the Associació Cetàcea’s members taking pictures, which are included in the catalogue of the species (Picture: Associació Cetàcea).


To the fact that we study highly mobile species, we must add the movement of the boat from which we conduct the study and also that cetaceans only spend a short time outside the water. This means that many of the photographs are not of sufficient quality to be included in the catalogue or that the individual identification features are not seen in their entirety. To choose which ones have the sufficient quality, we use seven technical criteria that value, among others, the focus, the light, the position of the animal with respect to the camera, and that allow us to select only those fins with the highest quality, to include them in the Photo-identification catalogues.

And with the chosen photos, what do you do?

The first thing we do with the selected photographs from each of the seasons is to compare them to each other to determine if there are any individuals who have been seen on more than one occasion. Later, we compared the photographs with those that are already included in the catalogue, to see if the individuals sighted had been previously observed or not.

This process would not be possible without the dedication of the volunteers, who help us in each of its stages.

Since 2014, I imagine that you have had the opportunity to see many different species of cetaceans. However, which are the main ones you have observed?

Since we started the project, there have been four species we have observed most frequently. The most common are the striped dolphin and then the fin whale.

associació cetàcea, cetacis, catalunya, dofí llistat, stenella coeruleoalba
The stripped dolphin (Stenella coeruleoalba) is the most common cetacean species in the Mediterranean Sea (Picture: Associació Cetàcea)

Less commonly, we have seen bottlenose dolphins and Risso’s dolphins. Both the bottlenose dolphins and the striped dolphins have been observed at different times of the year. On the other hand, the fin whale has been usually seen between the months of March and June, which coincides with their annual migration to the feeding areas and the Risso’s dolphins have only been observed in spring. In addition, we also had a sighting of short-beaked common dolphins, an unusual occurrence in the north-western Mediterranean, and we also recorded a possible rough-toothed dolphin (Steno bredanensis), a highly unusual fact since it is a restricted species  in the Eastern Mediterranean, in waters near the Suez Canal.

And apart from cetaceans, during your adventures at sea, I imagine you have spotted seabirds and turtles. Is it so?

Apart from cetaceans, there are other species that we can observe relatively often. Before the taking our trips, we do not assure that we will see cetaceans, but we always say that we will be able to watch seabirds. In fact, it is quite common to observe different species of seagulls, terns, shearwaters, storm birds and parasites, and in the winter season gannets and Atlantic puffins. In addition, at certain times sunfishes, turtles, tunas, swordfishes and some invertebrates like the hydrozoa Velella velella. Each trip is a different experience and the sea is often surprising!

Reading the results of the study, I have seen that you have come to catalogue 90 different individuals. However, there are not many individuals who have seen again in different years. Can it mean that individuals no longer return in the area again?

There are different factors that could explain the low number of re-viewings in this phase of the study. A first factor would be that we are in a very early phase of the study, during which the number of re-viewings are usually quite low. Examining the evolution of the number of individuals catalogued in photo-identification studies, this usually follows an exponential pattern. This distribution is due to the fact that in the initial stages it is easier to photograph new individuals and, as the study progresses and the catalogue grows, the likelihood of re-viewing increases.

Secondly, it must be distinguished, however, that these 90 individuals belong to two different species and the results must be assessed separately. In the case of the Risso’s dolphin, for example, the photos come from a total of 5 sightings, and although there has only been a yearly survey, it is noteworthy that there are up to 6 individuals that have been observed in more than one occasion in the same year. Thus, in this case, the low number of re-watchings could be due to the low number of sightings.

cap d'olla gris, grampus griseus, catalunya, associació cetàcea
The Risso’s dolphin (Grampus griseus) is full of marks in the body due to interactions with other individuals (Picture: Associació Cetàcea).

In the case of the bottlenose dolphin, there are up to 6 individuals that have been sighted in different years, which could indicate some residence or some frequency of use of this habitat.

associació cetàcea, catalunya, cetacis, dofí mular, tursiops truncatus
The bottlenose dolphins (Tursiops truncatus) are the most known cetaceans, due to its presence in zoos (Picture: Associació Cetàcea).

Finally, I would like to point out that in both cases they are cetacean species that may have a fairly large distribution range. An example is the case of Dofina, a bottlenose dolphin that we have photographed twice, but which has also been seen previously in areas near the Strait of Gibraltar. This species, precisely, forms very stable populations in specific areas, and photo-identification studies carried out over many years have been able to determine its composition. We hope that in the near future, thanks to the work carried out in the framework of our study, we will be able to define more exactly the different communities of cetaceans that frequent the area of ​​study and to establish their degree of residence.

The results show that the striped dolphin and the Risso’s dolphin have a distribution farther from the coast, while the bottlenose dolphin is rather coastal. In contrast, the fin whale would be situated in an intermediate position. What factors do you think explains this distribution in space?

As you say, the four species we have sighted most often have a different distribution in space. In this sense, the bottlenose dolphin is usually find in shallow waters, close to the coast and linked to the continental shelf. On the other hand, the striped dolphin and the Risso’s dolphin usually frequent deeper waters, linked to the continental slope and its submarine canyons, although the striped dolphin can also be seen in shallower waters. Finally, the fin whale has a wider distribution, as we have seen in shallow water and in waters with depths greater than one thousand meters.

associació cetàcea, mar mediterrani, catalunya, cetáceos, cataluña
Map of the sightings made by Associació Cetàcea [Yellow: fin whale; Blue: Risso’s Dolphin; Red: Striped Dolphin; Green: Bottlenose Dolphin] (Picture: Associació Cetàcea).

With the exception of the fin whale, which is found in areas of much deeper waters in other areas of the Mediterranean, the distribution of the different species follows the same pattern as in other areas of the Mediterranean.

In general, one of the facts that has a great influence on the distribution of animals like cetaceans is their diet. Thus, species such as the Risso’s dolphin, that base their feeding in different types of squid, are distributed mainly in areas where its prey is abundant. On the other hand, species with a more general diet, such as the striped dolphin, have a wider distribution. In the case of the fin whale, it could be that it approached more superficial waters to feed by taking advantage of the primary spring production peaks.

associació cetàcea, cetacis, balena, rorqual comú, balaenoptera physalus
The fin whale (Balaenoptera physalus) is the second largest whale in the world, and lives in the Mediterranean Sea (Picture: Associació Cetàcea).

After all this time of study, what are the main conclusions you have drawn?

These first years of study have helped us to develop a working methodology that suits our needs and to have a first idea of ​​the species of cetaceans that frequent the area.

In this sense, we highly appreciate the work done, as it has allowed us to develop a very satisfactory work methodology that ensures meticulous data collection. In addition, we have also been able to understand the distribution of the different species, which allows us to manage with certain reliability the trips of sighting depending on the species that we want to study. Finally, we highly value the creation of the two photo-identification catalogues, since they allow us to have a better knowledge about the residence of the individuals of these two species.

However, it should be noted that much work remains to be done in order to have a better knowledge about the different communities of cetaceans, their distribution and their degree of residence.

The study area of ​​the photo-identification project is the Garraf coast. But, have you crossed your data with other databases from the same area or other areas of the Catalan sea to have a wider view of the entire Catalan coast?

At the moment, we have not yet compared our photographs with other databases of the Catalan coast, since we do not know if there is any database of these characteristics that is in the public domain. We believe that this would be a very important task in order to know the situation of the communities of cetaceans that frequent our coast. In this sense, we have given access to any person who wishes to consult our catalogues and our results through the website.

We would like to point out that, although we have not done any comparison with other databases of the Catalan coast, we have compared, and are comparing, all the photos of individuals catalogued with photo-identification catalogus made by other associations in The Alboran Sea, the Gulf of Vera, the Strait of Gibraltar and the Gulf of Cadiz (Spain), which are included in a set of public domain catalogus called CetIDMed.

What factors may negatively affect cetacean species in the study?

The factors affecting the cetaceans we studied could be extrapolated to cetacean populations in general. Thus, we could say that the factors that affect them most are those of anthropic origin. There are several studies that show that depending on the species they can be more or less affected, in general, by: the contamination, both visible and micro particles that enter the trophic network, as well as the noise pollution caused by the increase of sea traffic, overfishing, bycatch and direct catches (in other countries).

One of the most important threats facing many species of cetaceans is coastal development, the construction of offshore wind farms or oil prospecting. In addition, the last two examples are associated with a number of previous activities with high levels of underwater acoustic pollution, which can negatively affect cetacean species such as sperm whales, beaked whales and some dolphin species that base their feeding on echolocation, in other words, the detection of preys and objects by means of the production of sounds. Thus, initiatives such as that presented by Alianza Mar Azul on the creation of the Cetacean Migration Corridor, a particularly protected area in the Levantine-Balearic marine demarcation of the Mediterranean, are very positive in order to preserve areas of importance for these species.

I see that since 2014 you have done a lot of work in the study. Now, I would like to ask you a more general question, leaving aside the study a bit. The observation of cetaceans from boats, an increasing activity, can affect the behaviour of these individuals?

Cetacean observation has increased, especially since the 1980s, and in some places is a very important revenue industry. The presence of vessels can have adverse effects on cetaceans and, as you say, alter their behaviour, with even long-term implications such as the reduction of pregnancies as a result of reducing the time spent on socialising, or also, affecting their energy balance, either by reducing energy (less food), or by increasing energy expenditure.

The reasons mentioned above should be sufficient for all those who are involved in the observation, research of cetaceans, or simply to encounter this group of animals on a random basis, to comply with the established measures of the cetacean protection space, establishing three surface areas around cetaceans (the exclusion zone, restricted area and approach zone), an aerial zone and an underwater area, depending on the distance of the boat with respect to the group.

Associació Cetàcea considers it fundamental to comply with the rules of respectful navigation with cetaceans, in order to minimise the interaction with this group of animals to avoid any negative effects that may occur. What’s more, we offer to make informative talks on this subject to encourage respect in the observation of these animals.

Now I would like to ask some more questions so that people can get to know you a little more. Your main activity is the study of cetaceans. While you cannot be sure that cetaceans will be seen on all trips, how often have you seen them?

This is a very important question. The first thing we do before leaving harbour is to remind all the attendees that we cannot assure the sighting of cetaceans. It is important to remember that these are very mobile animals, which are in their natural habitat and therefore, may not be close to the boat during the course of the adventure. That said, we must admit that the percentage of trips in which we have seen cetaceans is quite high, being very close to 80%.

And, apart from sighting trips, what other activities do you do?

The sighting trips are the main activity the association carries out, since they are part of the Photo-Identification project. Apart from that, the association carries out other training and outreach activities such as training talks, informal talks or round tables. We sporadically carry out educational activities for children and families with the intention of showing that our coast is a treasure of biodiversity and that we can collaborate in protecting it. We can all contribute to take care of our sea with small daily gestures (recycle, reuse and reduce waste).

What future plans has Associació Cetàcea?

The activity of the association is based on the work we do every day. Anyway, the near future is to continue carrying out the photo-identification study and the other activities that we have carried out.

Surely now that people know better, there will be some of our readers who will be interested in collaborating with you. In what way can they do it?

We currently have a team of volunteers who collaborate with us in the photo-identification project and help us with the tasks of valuing and cataloguing photographs. In fact, it should be taken into account that the members of Cetàcea perform their work without receiving any kind of economic compensation and during their free time and, although we would like to be able to devote much more time to our study of cetaceans, this is not possible. Hence, volunteers play a key role in this study because, without their selfless collaboration, the valuation and comparison of photographs would advance much more slowly.

Another way to collaborate with us and enjoy a day of sailing is to accompany us in one of the trips of the study. All the people who sail with us is helping us finance the rental of the boat and also have the possibility to see how the data and photographs are taken and can observe several marine species .

A third way of collaborating with us is by sponsoring a dolphin from our catalogus or being a member of our teaming team.

For more information on any of the types of collaboration, we encourage everyone to contact us at

Thank you very much for agreeing to do this interview, the truth is that I am really exited. It was with you that I made my first sighting trip in Mediterranean waters. If you want to know them better, you can access the web, Facebook and Twitter

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