Action Sheet

  • Location :
    Gulf of St Malo, France
  • Species status :
  • Period :
    January 2010 - December 2012


Field operator


The bottlenose dolphin population on the west coast of the English Channel is curious because it is sedentary and the largest population of the species in France. Unfortunately, it is subjected to many pressures from human activities such as boating, commercial shipping, fishing, etc. There are future plans to build windfarms in the region, however the impact of these on the marine mammals and on the surrounding environment is still poorly known. There is therefore an urgent need to deepen our knowledge about this population.

The GECC is an organization that specializes in the study of bottlenose dolphins (Tursiops  truncatus) in the waters of the English Channel. It has carried out a number of campaigns at sea to monitor and identify the dolphins, using mainly photo-identification. The GECC has also developed a number of activities to raise awareness among the general public on the dolphins´ presence in the region. For several years, the GECC has also established a volunteer observers network, composed principally of fishermen and boatmen who provide it with any sighting information they may have obtained at sea. The first bottlenose dolphin population distribution maps were developed by the GECC in 2009.

Field operator

Structure Name:

GECC (Group for the Study of Cetaceans of the Cotentin and mammals of the Channel)



Main tasks:

  • The study of cetaceans and pinnipeds attending the Normandy coast and the sea of ​​the Channel
  • Raising awareness and educating the general public to learn about these marine mammals and effectively contribute to their protection.        


  • Promote the general awareness concerning the bottlenose dolphin population of the St Malo Gulf.
  • Provide answers to the managers of the area (DIREN, Coastal Protection, Marine Protected Areas Agency) in order to develop appropriate conservation plans for the species.
  • Inform and educate the general public to promote the area´s sustainable development.


  1. The photo-identification
  2. Biopsies
  3. Genetic analysis
  4. The diffusion of knowledge among the general public

    The photo-identification

    The photo-identification will be used to track individual dolphins and it is to take pictures fins at sea trips instead of being physically marked odontocetes will be identified through photographs, the characteristics their dorsal fin (nicks, scratches) that act as natural markings which are an alternative to artificial marking. The data obtained by photo-identification can be used to analyze associations between individuals, social structure of the group, habitat use, movements of the distribution and demographic parameters of the population (its size, the probability Survival, recruitment and growth rates).

    Expected Results:

    • The identification of individuals in the population with a characteristic dorsal fin
    • Analysis of associations between individuals, social structure of the group, habitat use, movements and distribution
    • Information on the demographics of the population


    Currently, identification photography book by an incomplete picture of population structure of bottlenose dolphins along the coast, as well as human impacts experienced by these mammals. To advance the knowledge of these animals (their lifestyle and their behaviors), GECC has proposed to perform biopsies on these animals. Consequently, the association has requested and obtained a ministerial permit for this which is valid until September 2012. Biopsies are very important scientific tools that will help deliver DNA, as well as data on the feeding ecology of the species and contaminants. However, GECC agrees to stop the biopsies at the slightest sign of discomfort among bottlenose dolphins.

    Expected Results:

    • Knowledge of the sex of the animals, which can provide important data on the social structure
    • Comparison of data population of bottlenose dolphins in the Channel with other European populations identified
    • The study of the diet of bottlenose dolphins
    • The assessment of contamination levels in dolphins from La Mancha

    Genetic analysis

    It is especially important to determine the sex of the dolphins when considering the fact that organochlorine levels in male dolphins increase steadily with age. Females do not tend to store these pollutants in their organism. The sexing of the animals may also provide accurate and important information on the social structure of the population.

    The English Channel bottlenose dolphin genetic data will enable the comparison of the latter with genetic information from other European populations. This will confirm whether relationships exist between the different bottlenose populations and whether the studied population is an open or closed population

    Expected Results:

    Study of the diet of the species

    Biopsies can also be used to study the species´ diet through stable carbon and nitrogen isotope analyses of the dermal protein. This determines which species the dolphins have fed upon.

    Evaluation of contamination levels

    Through the biopsies, it will also be possible to determine the English Channel dolphins´ contamination levels. The dolphin trophic chain reflects very clearly the bioaccumulation of metals.  Dolphins are therefore good pollution indicators.

    The diffusion of knowledge among the general public

    One of the most important goals of the GECC is to diffuse its work and keep the public regularly informed about its activities.

    Expected Results:

    The diffusion of the organization´s work through:

    • A new GECC website
    • An annual summer campaigns
    • The redesigning of an educational booklet
    • Conferences to train and inform fishermen, boatmen and others.
    • Interventions in schools

    Results 2010

    The The Explorers Foundation-GECC partnership was signed in June 2010. Following this event, the GECC embarked itself in a search to find other sources of funding to finance the rest of the project.

    Every year the GECC´s workers and volunteers organize a summer festival. In 2010, the festival was held in the first two weeks of August. The GECC invited MAAF employees to come to the organization´s headquarters and participate in the different activities:

    • preparing the festival mounting of the exhibition
    • welcoming the public and animation exhibition

    The number of MAAF workers that attended the 2010 GECC summer festival was limited due to the unfortunate poor weather conditions and the fact that the event hadn´t been planned well in advance. A second visit for MAAF employees was organized in the first week of September 2010.

    The GECC research team conducted several successful boat outings in August and September 2010, during which a considerable number of dolphins were photographed and identified. Two outings that were carried out in September were especially successful with when more than 200 dolphins were photographed. GECC volunteers are presently working diligently at the organization´s headquarters to analyze all of the photographs. With this information it will be possible to make a first estimate of the total bottlenose population inhabiting the Normandy-Britanny Coast.


    - In June, 2012 -

    Norman Bottlenose dolphins on TV

    A team of the regional TV channel France 3 Basse-Normandie came to film the GECC (Group of Study on Cotentin Cetaceans) activities on the bottlenose dolphin monitoring. The report was broadcasted on the 30th of May, on the news program of 12am.

    Dorsal fin of Bottlenose dolphin (© GECC)

    - In April, 2012 -

    Bottelnose Dolhpins noisier in the Minquiers than in Cancale

    Dolphins and boat acoustic monitoring recently showed there were more dolphin emissions in the Minquiers (archipelago of Normandy) than in Cancale (coastal city of Normandy). An hypothesis is suggested: is it because of a higher number of boats in Cancale? To be continued…

    Bottlenose dolphin of Normandy (Source : GECC)

    - In March, 2012 -

    Bottlenose dolphins of Normandie are not alone

    During all year 2011, members of the observatory network have provided the GECC (Cotentin’s cetaceans research group) 455 observations of marine mammals. Twelve species have been identified. Exceptional visitors of the year were the Sperm whale, the Humpback whale and the Fin whale. Without any surprise, the most seen is the Bottlenose dolphin.

    At the beginning of this year, the GECC started Bottlenose dolphins skin sample analyses. The first result reveals the gender of 67 individuals: 49 males and 18 females (gender can’t be identified visually). This information is very important to understand and analyse the structure of Bottlenose dolphin populations.

    - In December, 2011 –

    The GECC receives the “Admissible Solidaire” award organized by Grenoble School of Management!

    For the last three years, the Grenoble School of Management has awarded prizes as part of an initiative it has named “Admissible Solidaire”. The objective of this initiative is simply to foster greater awareness among those attending business schools in favor of solidarity, while simultaneously supporting worthwhile causes.

    Prizes are awarded in accordance with the results of votes cast by first-year students of the school.

    During this year’s awards ceremony, held on September 12th, 2011, the 10,000 euros that were awarded by the School were distributed among three organizations, one of which was the GECC which received about 2000 €.

    - In November, 2011 –

    Recovery  of the first acoustic recordings

    In early November data from the two hydrophones were recovered. However, a few problems were encountered. The buoy marking the position of the hydrophone at Cancale was found 800 meters from where it should have been. It took several dives to locate the device in order to retrieve the data and return the device to its original location. The acoustic unit at Minquiers however was found in its original position. The data are being analyzed and should provide the research team with precious information about the area´s dolphin population as early as December.

    - In October, 2011 –

    The GECC is expanding its field of investigation

    To get around the problem of adverse weather conditions when recording different observations at sea, the GECC has decided to invest in a “gps pda”. This small device that fits in the hand, has a touch screen that permits the user to note quickly and efficiently all types of information: data on birds, human activities, weather conditions and marine mammals.

    Reaching out to school students and the creation of an educational kit.

    The GECC began, at the beginning of October, to extend its activities to cover groups of school students. For this purpose, the association has created PowerPoint presentations, a short film and an educational booklet containing text, exercises and games. The GECC has given itself four months to test and tweak these educational tools before making them available to the general public in the form of an educational kit.

    - In September, 2011 -

    Keeping an ear on the Dolphins

    On Tuesday, August 9th 2011, researchers from the GECC (Groupe d´Étude des Cétacés du Cotentin) installed a first hydrophone (acoustic detector) in the Mont Saint-Michel Bay. This acoustic detector will remain at sea until January 2012. The Mont Saint-Michel area was chosen for the study because it is frequently visited by both the dolphins and pleasure cruises.

    Already tested near the port of Cherbourg, the hydrophone will allow the researchers to determine in which periods the dolphins are most present in the area and to analyze the disturbance factor arising from  shipping.

    The installation of a second acoustic detector unit is planned for the south of the Minquiers archipelago.

    - In August, 2011 -

    What does the bottlenose dolphins eat?

    In July, members of the GECC team began going out with fishing vessels to collect the fish or mollusks that are most likely eaten by the dolphins. In total, the researchers need about thirty samples of twenty different species. This sampling must carried out across the whole of the Norman-Breton Gulf.

    The comparison of the stable “isotopes” present in all of these prey with that present in dolphins ought to shed more light on the diet of these marine mammals. Even though this method is not very precise, it is the only one that is currently available.

    The Observer Network spreads to the English coast

    The GECC has set up a partnership with the English association SEAWATCH, that is also dedicated to the observation of marine mammals. This merger will allow the French association to determine which species can be found in the English coastal waters close to their study area.

    A first observation map of the months of April and May 2011 have allowed the GECC to note the presence of Lagenorhynques on the English coasts, a species that has never been observed on the French Coasts.

    A map compiling all of the dolphin observations will be updated every two months.

    - In July, 2011 –

    Acoustic beginnings and disappointments!

    In February 2011, the GECC (Groupe d´Études des Cétacés du Cotentin) research team implemented two acoustic detectors on a landing craft that had sunk in June 1944. Three months later, unfortunately only one of the two devices had been recovered despite the researchers having taken every step to prevent the removal of the devices by fishing gear. They hadn´t however envisaged the possibility that the devices might also get removed by the divers.

    To avoid such events in the future, the team tested another type of anchorage, which, would hopefully resist such happenings. The detectors are now fixed to four concrete blocks and the whole structure weighs over 400 kg. Two of these anchorage structures are being installed; the first at Cherbourg-Octeville and the second at Cancale. They will permit the GECC to enrich their knowledge about the bottlenose dolphin population.

    A big microphone for Flipper

    On May 5th, the GECC´s research team tested the placing of an acoustic detector in the sea near the port of Cherbourg. The structure, composed of four cement blocks and an iron frame, weighs about 300kg. It was constructed ​​entirely by the young students of the “Centre Educatif Renforcé” at Bigard. The work was carried out by four experienced divers and by the boat “Vieux Copain”, a sailboat belonging to the association “Voiles Ecarlates”. This first test was a real success.

    The objective was to install this structure at the end of May, on the west coast of the Cotentin in order to assess the feasibility of studying marine mammal populations simply through acoustic signals. The long-term objective of this initiative would be to be able to reduce the number of trips made out to sea by the research team and thereby to disturb the dolphins as little as possible while still continuing to gain more knowledge of them.

    Piracy in troubled waters!

    On May 10th, the GECC research team went out to sea to retrieve the two hydrophones that had been installed last February south of the St Marcouf islands. To the GECC´s surprise, one of the devices had disappeared. The researchers, who had chosen a little-known ship wreck areas, hoping that the hydrophones would be safe from fishing equipment, had never envisaged this type of scenario. There was great disappointment within GECC.

    The team was still able to retrieve one of the two recorders, thanks to which the team will be able to view everything that has been happening underwater during these last three months of the research program.


    -In June, 2011-

    The GECC  presents  its  first findings to the scientific community

    From the 21st to the 23rd of March 2011 the GECC (Groupe d’Etude des Cétacés du Cotentin) presented the results of its research on the bottlenose dolphin population to the scientific community during the European Cetacean Society symposium, which took place in Cadiz, Spain.

    The work of the association has generated considerable interest. In fact it was the first time that research results had been made available on the Normandy-Brittany bottlenose dolphin population, a species which is arousing growing interest. This communication meeting will open up for the GECC the prospect of a number of collaboration opportunities with research institutes and laboratories interested in sedentary bottlenose dolphin populations.

    -In June, 2011-

    One of the largest populations of coastal bottlenose dolphins in Europe.

    The GECC  (Groupe d´Étude des Cétacés du Cotentin) has been trying for the last few years to determine the best method of estimating the total bottlenose dolphin population living off the Normandy-Brittany Coast. The organization’s researchers have considered the best solution to be the programming of observation sessions at sea over a period of two days in the summer to ensure that the whole of the study area and the maximum possible number of groups of dolphins are covered.

    Initial figures indicated the presence of 400 bottlenose dolphins, from which it may be concluded that the English Channel bottlenose dolphin population is one of the largest in Europe. The next largest populations can be found in the Gulf of Cadiz with 350 individuals and the Strait of Gibraltar with 300 individuals. Other European populations are smaller with about 200 individuals at Cardigan Bay in Cornwall and about 130 individuals in the Moray Firth in Scotland.

    -In May, 2011-

    Weather conditions are much better and this has allowed the GECC (Groupe d´Etude des Cétacés du Cotentin) to make more frequent trips out to sea. In recent trips, the GECC researchers have been able to measure the progress of the porpoise population.

    It is interesting to note that the population has been observed to increase from 2 in 2008, 11 in 2009 and then 21 in 2010, which tends to confirm the findings and conclusions of many scientists, according to whom this species has been, over the last few years, once again making its home in this part of the English Channel.

    -In March, 2011-

    Marine Mammal Observers Network of Normandy-Britanny Coast

    The GECC´s (Groupe d´étude des cétacés du Cotentin) Marine Mammal Observers Network is a tool for increasing the knowledge and contributing to the conservation of the Bottlenose dolphin. This network allows a close watch to be maintained and, if necessary, for users of the sea to be alerted to the need to maintain a sustainable coexistence between the marine mammals and the different anthropogenic activities carried out in the area. In 2010, the GECC received data from 249 sightings pertaining to eight different species of marine mammals.

    This year bottlenose dolphin sightings are once again the most common accounting for 70% of total sightings. For the first time, an extension of the movement of the bottlenose dolphin population west of the Contentin was detected. In fact the development of the observation network enabled the presence of bottlenose dolphins off Etables-sur-Mer, northwest of St. Brieuc to be confirmed. It turned out that the individuals identified in the photographs corresponded to the ones that are regularly seen in the Bay of Mont Saint-Michel.

    - February 2011-

    More than 82,000 Bottlenose dolphin photographs taken by the GECC!

    Since the beginning of December 2010, the team from GECC (Groupe d’Etude des Cétacés du Cotentin) has been focusing its effort on identifying Bottlenose dolphin individuals from photographs taken in 2010 and also in preparing its program of work for the Spring. Since the birth of the organization in 1995, a total of 82 434 photographs have been  taken but  only 54% have been analyzed. There are still 37 955 photographs to be analyzed. This work is presently being carried out by the GECC paid staff and volunteers. It is hard work requiring considerable rigor and attention to detail.

    -In November, 2010-

    Study on the social structure of the bottlenose dolphin population in Normandy

    After having analysed all the photographs, the GECC team will be able to discern the structure of the resident population of bottlenose dolphins. The main objective is to know whether there is only a single population of dolphins and whether it is made up of several groups depending upon sex, social status or other factors. The three areas where the individuals have more frequently beenobserved are shown on the map.Each square corresponds to an individual whose name is labelled. A line on the map denotes that the individuals have been seen together at least once. A color code represents the zone or zones where the individual has been observed.

    The individuals observed only in the Bay of Mont Saint Michel (light blue) and in the North (yellow) are never seen together. However, they interact with common individuals who have been spotted in two zones or in the whole of the area. In addition, some of the individuals are seen in only one sector while others are observed over a wider geographical area (dark blue, dark green, orange, light green) or over the whole observed area (red). This diagram shows us that the population forms a single although spatially structured unit.


    - In October, 2010-

    The first recordings have been made!

    The first sounds, also called «clicks» or rattling sounds recorded by the C-POD detectors were closely analyzed to verify the reliability of the recordings and of the interference that could decrease the quality of the latter. The solid particles suspended in the water or the microbubbles created by the waves and the passage of vessels can produce the « clicks » in the recordings. These clicks are associated to the impact of the particles or microbubbles hitting against the hydrophone sensors. The signal is characteristic to the vaquitasound emission and consists of a very specific set of clicks. For greater caution however, C-Pods will be placedat about 10m from the sea bottom to limit the effects of microbubbles.

    Biopsies, the serious matters have finally begun!

    In late September the GECC team started carrying out the biopsies necessary for the geneticcharacterization of the bottlenose dolphin population. For this, they used arrows shot with a crossbow. This method is very commonly used on this species but nobody has carried it out on the Normandy population and the GECC team had some apprehension about the animals´ reaction. The results of the first shots were not evident but the research team was soon reassured. Indeed, the animals had a mild response to the impact but showed no escape reaction. To the team’s astonishment, what bothered the dolphins most was when the arrow missed the target. The reaction of the dolphins was to just dive away from the boat.


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