Presentation
Study
areas
Target
species
Overview
of methods
Survey
effort
Dolphin
encounters
Photo-identification
Common dolphin population abundance and trends
Dolphin
feeding ecology
Dolphins found stranded or floating adrift
Tissue sampling for genetic and toxicological analyses
Evidence of dolphin bycatch in fishing gear
Other dolphin-fisheries interactions
Monitoring of fish and shell farms
Other marine species
Publications
Education
Personnel
Supporters
Collaborations and synergies
Photo albums
Get involved!
The Ionian Dolphin Project is a long-term research and conservation programme conducted by the Tethys Research Institute in the eastern Ionian Sea (Greece).
In 1991 the Tethys Research Institute started a study around the island of Kalamos. Initially meant to be a long-term investigation on the ecology and behaviour of common dolphins in a central Mediterranean hotspot, the study documented their sharp decline. Common dolphins declined dramatically from about 150 to 15 animals between 1995 and 2007. Actions by Tethys aim to facilitate their recovery. Bottlenose dolphins are found in the same area in relatively small numbers, but have stable trends and were studied intensively over the past decade. Ongoing monitoring allows to detect changes in population status and propose timely management measures.
In 2001 Tethys started a study in the Amvrakikos Gulf, where bottlenose dolphins are the only cetacean species encountered. This study showed that about 150 dolphins live in the Gulf. These dolphins are members of a resident community showing unique behaviour and ecology. The Gulf is also inhabited by loggerhead sea turtles Caretta caretta and has a rich bird fauna including rare species. Research carried out by Tethys is documenting how the local dolphin community interacts with its environment and how human activities - particularly fishing and pollution - may influence its conservation status.
In 2008 Tethys opened a new field station on the northern shore of the Gulf of Corinth to investigate the ecology and status of three cetacean species: bottlenose dolphins, striped dolphins and short-beaked common dolphins.
Research by Tethys is providing support to management efforts in the eastern Ionian Sea, through actions including:
- continued monitoring of dolphin groups through field research methods including boat surveys and individual photo-identification, to detect population trends, identify critical habitat, and gain further insight into ways of mitigating the present threats;
- research on factors threatening the local ecosystem, particularly with regard to the impact of fishing;
- public awareness initiatives (e.g. involvement of a large number of volunteers, “Dolphin Days” and other events organized locally, public presentations, lectures at local schools, video productions);
- contacts and meetings with the local Authorities and fishermen organisations, aimed to a) raise awareness on the need to establish measures to protect dolphins and implement the existing regulations (e.g. with regard to illegal fishing activities); and b) identify ways to compensate any losses for fishermen or promote a progressive re-conversion of their activities;
- dissemination of information in the scientific literature and provision of sound data and management proposals to international agreements and bodies concerned with the protection of marine biodiversity.
The area of Kalamos was proposed as Marine Protected Area (MPA) at the 3rd Meeting of the Parties to UNEP/CMS Agreement on the Conservation of Cetaceans of the Black Sea, Mediterranean Sea and contiguous Atlantic Area (ACCOBAMS, 2007). The ACCOBAMS Scientific Committee also recommended the Parties to consider the Amvrakikos Gulf as a candidate MPA. Both candidatures were based on evidence provided by Tethys.
The Amvrakikos Gulf is a semi-closed sea situated in north-western Greece, stretching over about 35 km and covering an area of approximately 400 km2 (excluding its enclosed marshes and lagoons). It is virtually a closed basin as its only link to the open Ionian Sea is a narrow strait, the Preveza channel, 370 m wide and 5 m deep in its narrowest and shallowest points. The sea floor is mostly 30 m deep (max depth 60 m) and covered with mud or sand. The waters are murky (Secchi disk readings ranging between 2-12 m), eutrophic and strongly affected by runoff from the two rivers Louros and Arachthos.
The study area centred around the island of Kalamos is delimited by mainland Greece and the eastern coast of the island of Lefkada, and it includes the islands of Meganisi, Kalamos and Kastos. This area covers approximately 1,000 km2 of sea surface. The sea floor is mostly 50-150 m deep, with rocky coasts and shallows covered by seagrass meadows. Waters are transparent (Secchi disk readings ranging between 10-30m), oligotrophic and unaffected by significant river and agricultural runoffs.
The Gulf of Corinth is a semi-closed basin of extraordinary interest. It is a deep inlet of the Ionian Sea separating the Peloponnese from western mainland Greece. It is bounded in the east by the Isthmus of Corinth, and in the west by the Strait of Rion, which separates the Gulf of Corinth from the outer Gulf of Patras, where the narrowest point is crossed by the Rio-Antirio bridge. Waters up to almost 1000 m deep are found relatively close to the coast, so that pelagic species such as the striped dolphin are found near shore.
The Ionian Dolphin Project study areas in the eastern Ionian Sea, Greece.
Target
species
Short-beaked
common dolphin Delphinus delphis
Once one of the most common cetacean species in the Mediterranean, the common dolphin has declined throughout the region during the last 30-40 years. In 2003 the Mediterranean common dolphin population was classified as Endangered in the IUCN Red List of Threatened Animals. In 2006 Mediterranean common dolphins were also included in Appendix I and II of the Convention on the Conservation of Migratory Species (Bonn Convention - CMS). The causes of this generalized decline remain poorly understood but are thought to include prey depletion and bycatch.
The eastern Ionian area around the island of Kalamos has been included by the Greek Ministry of the Environment in the Natura 2000 network ("Sites of Community Importance") under the 9243 EEC “Habitats” Directive. The area has also been identified as one where pilot conservation and management actions should be developed and implemented immediately to preserve common dolphins’ habitat.
In 2004 ACCOBAMS produced a Conservation Plan for Mediterranean common dolphins, where Kalamos was identified as an area of high conservation importance. The importance of the area of Kalamos was also highlighted in the IUCN 2002-2010 Conservation Action Plan for the World’s cetaceans.
Despite these designations, the formerly resident and abundant common dolphin community living around Kalamos has shown a continuous decline beginning in 1995. Encounter rates of large tuna also showed negative trends. The decline of high-order marine predators feeding on epipelagic prey was consistent with the hypothesis of prey depletion, likely resulting from intensive exploitation of local fish stocks, particularly anchovies and sardines.
In the Gulf of Corinth, common dolphins are often found in association with the more abundant striped dolphins. Such association may be an adaptive behaviour developed by a small and probably remnant unit of common dolphins to maintain social bonds and enjoy the benefits of living in groups.
Common bottlenose dolphin Tursiops truncatus
Bottlenose dolphins, the most coastal species in the Mediterranean, have been affected in numerous ways by human activities, including culling campaigns conducted until the 1960s. In recent times, incidental mortality in fishing gear, prey depletion as a result of overfishing and habitat degradation, boat traffic, noise, and health effects caused by pollution are regarded as major threats. Based on a suspected decline of at least 30% over the last 60 years, Mediterranean bottlenose dolphins were proposed for classification as Vulnerable in a recent assessment by the World Conservation Union (IUCN) and ACCOBAMS.
A relatively stable presence of bottlenose dolphins was observed around Kalamos. About 25 animals have shown high levels of site fidelity over the past decade, while others use the area only occasionally. Their flexible feeding habits and opportunistic behaviour may allow them to withstand the effects of overfishing and habitat degradation, but they survive at low densities.
An abundant community of bottlenose dolphins lives in the Amvrakikos Gulf. Intensive photo-identification work showed that these dolphins have high levels of site fidelity within the Gulf. Individual movements in and out of the Gulf are limited, probably owing to dramatic differences between the shallow, highly productive, turbid waters of the Gulf and the deeper, oligotrophic, limpid Ionian Sea open waters. Population size in the Amvrakikos Gulf is about 150 individuals - a density much higher than that found in the area of Kalamos. The Gulf is reportedly facing problems including alteration of water balance, chemical pollution, eutrophication and illegal fishing, resulting in significant ecosystem changes. However, dolphins appear to be thriving, likely due to the abundance of suitable prey – sardines in particular.
Bottlenose dolphins are also being studied in the northern Gulf of Corinth. Several animals photo-identified in this area had been previously seen around Kalamos, about 170 km far, providing evidence of long-range movements by some individuals.
Striped dolphin Stenella coeruleoalba
Striped dolphins are arguably the most abundant cetacean species in the Mediterranean Sea, and yet they are considered Vulnerable in the region, due to massive mortality events caused by viral infections that have been related to contamination by xenobiotics and possibly prey depletion. They area also exposed to high levels of mortality in fishing gear, particularly driftnets.
The population of striped dolphins living in the eastern Gulf of Corinth is apparently isolated from the rest of the Mediterranean Sea. Concerns over their status and extinction risk of striped dolphins living in the inner part of the Gulf are raised by the animals’ high degree of geographic isolation and likely reproductive closeness. The work by Tethys aims to generate reliable information to support conservation action.
Visual surveys are conducted on a daily basis by means of inflatable craft with rigid hulls powered by four-stroke outboard engines. Individual photo-identification is used to catalogue dolphins seen in the study area and obtain information on their abundance, movements (e.g. immigration/emigration), habitat use, social organisation and reproductive success.
The position, movements, group size and composition, and behaviour of the dolphins is recorded during long-lasting observation sessions, through a standard behavioural sampling routine. This information is analysed by means of GIS software.
Drifting scales lost by fish prey following predatory events performed at the surface by the dolphins are collected by means of a dip net. The scales - preserved in ethanol 80% - are analysed to identify the dolphin's prey species, by matching them with a scale atlas of known fish species collected in the study area.
Marine species (including sea turtles, monk seals, tuna, mobulas, swordfish and seabirds) observed during the surveys at sea are recorded and photographed. Dead dolphins and sea turtles found stranded or adrift in the study area are inspected, and causes of death identified whenever possible. Biological samples are taken for further investigations. Occurrence of dolphin and sea turtle bycatch in fishing gear is recorded.
The project includes investigations aimed to assess the dynamics of interactions between dolphins and local fisheries, the monitoring of fishing effort. It also includes public awareness and capacity building actions.
Surveys to monitor dolphins around Kalamos were conducted from sailing vessels between 1991-1994, and since 1995 from inflatable boats with fibreglass keels. Surveys were conducted ad libitum in early years. In recent years, pre-defined survey transects are also used for the long-term monitoring of the study areas. All survey transects around Kalamos and those within and outside of the Amvrakikos Gulf were covered at least once per month.
Research effort around Kalamos is normally conducted in the warm season and covers 4 to 7 months per year. Research in the Amvrakikos Gulf is carried out year-round since April 2006.
The Kalamos dataset, 1991 - 2008
Data around Kalamos were collected during a total of 87 months spent in the field across 18 years of research, totalling 1,886 hours spent with 1,758 dolphin groups.
A total of 1,237 daily surveys were conducted in years 1991-2008. The navigation effort totalled 71,411 km. Across 18 years, 502 sightings of common dolphins and 444 sightings of bottlenose dolphins were recorded.
Dolphin behaviour has been recorded since 1996, sampled at intervals of 3 min (1996-2001) and then 6 min (2002-2008). Individual dive intervals were also timed between 1996-1999. A total of 23,442 record units (“samples”) of behaviour were recorded: 8,688 for bottlenose dolphins and 14,754 for common dolphins. These samples include position, group size and composition, group formation, directionality and speed of movement, surfacing pattern, dive duration, dolphin activity and behavioural events, presence of birds and bird data, and several other variables.
In addition, a total of 15,472 individual dive times of common dolphins and 5,412 of bottlenose dolphins were timed to investigate dolphin surfacing patterns and feeding behaviour.
Routes surveyed under favourable conditions (“on effort”) around the island of Kalamos in years 1991-2008.
Summary of research effort around Kalamos (1991-2008). Dd = Delphinus delphis, Tt = Tursiops truncatus.
The Amvrakikos dataset, 2001 - September 2008
Data in the Amvrakikos Gulf were collected during a total of 45 months spent in the field over 8 years of research, totalling 565 hours spent with dolphins.
A total of 453 daily surveys were conducted in years 2001-2008. The navigation effort totalled 20,852 km. We made 411 sightings of bottlenose dolphins, and 315 of loggerhead turtles.
Table 2 shows the research effort in the Gulf until September 2008. Data continue being collected as this report is being written.
Since 2005 dolphin behaviour was sampled based on 5 min observation intervals. A total of 4,020 units (“samples”) of behaviour were recorded. These samples include position, group size and composition, group formation, dolphin activity and behavioural events, presence of birds and bird data, and several other variables.
Individual dive intervals were also recorded starting in 2006, totalling 546 individual dive times, to investigate bottlenose dolphin surfacing patterns and feeding behaviour.
Routes surveyed under favourable conditions (“on effort”) within and outside of the Amvrakikos Gulf (2001-2008). Multiple coverage of pre-defined survey transects appear as a single line.
Summary of research effort conducted in the Amvrakikos Gulf (2001 - September 2008). Tt = Tursiops truncatus; Cc = Caretta caretta.
The following figures show the initial positions of dolphin sightings, and dolphin movements in the study area around Kalamos and in the Amvrakikos Gulf.
Sightings of bottlenose dolphins (blue dots) and common dolphins (green triangles) around Kalamos in years 1991-2008.
Only the initial position of sightings is shown.
Movements of bottlenose dolphins (blue lines) and common dolphins (green lines) around Kalamos in years 1991-2008.
Sightings of bottlenose dolphins (blue dots) in the Amvrakikos Gulf (2001 - September 2008). Only the initial positions of sightings are shown. One sighting was made in the open waters facing the Gulf, out of 667 km of survey effort under favourable conditions.
Movements of bottlenose dolphins (blue lines) in the Amvrakikos Gulf (2006 - September 2008), recorded at 1 min intervals. Dolphin movements were not recorded prior to 2006.
Individual photo-identification based on long-term natural marks on the dolphins’ dorsal fins was performed extensively with cameras equipped with 70-200mm f2.8 zoom lenses. Colour transparency film (ISO 100) was used in the early phases of this study, and then digital photography was systematically adopted. Transparencies were scanned and turned into digital images. Both transparencies and digital photos were then cropped around the dorsal fin and visible part of the body and selected using consistent criteria (e.g. entire fin visible, right angle, appropriate sharpness and resolution).
Following a quality-based selection, the total catalogue 1991-2008 included 69,709 photos on which photo-identification an other analyses were performed (Table 3).
Photo-identification allowed to obtain information on individual movement patterns, habitat use and preferences, reproductive success, social organization, population abundance and trends of common dolphins and bottlenose dolphins living around Kalamos and in the Amvrakikos Gulf.
Number of dolphin photos taken around Kalamos and in the Amvrakikos Gulf between 1991 and September 2008.
Dd = Delphinus delphis, Tt = Tursiops truncatus. NC = not computed.
Dorsal fins of two well-marked bottlenose dolphins (above) and screen capture of one of the database programmes used for dorsal fin analyses (below).
Residency patterns of 165 common dolphins identified around Kalamos between 1993 and 2008, based on long-term natural marks on their dorsal fins.
Residency patterns of 101 bottlenose dolphins identified around Kalamos between 1993 and 2008,
based on long-term natural marks on their dorsal fins.
Residency patterns of 140 bottlenose dolphins identified in the Amvrakikos Gulf between July 2001 and December 2008, based on long-term natural marks on their dorsal fins.
Common dolphin population abundance and trends
Detailed information on population abundance and trends obtained from photo-identification studies is being published in the scientific literature (see Publications) and is not reported here.
The most impressive information recorded over the years concerns the dramatic decline of common dolphins around Kalamos. Common dolphin numbers decreased from 150 to only 15 animals in ten years, and the study documented an immediate risk of complete eradication (Bearzi et al. 2008).
A few more common dolphins were encountered in the study area in 2008, during a total of 7 sightings, indicating that while a resident common dolphin population no longer exists around Kalamos, this area still represents important habitat and the surviving common dolphins that have been spreading over a larger region may be able to recolonize if appropriate management measures are put in place.
Abundance trend of common dolphins around Kalamos in 1995-2007.
Occurrence patterns of common dolphins around Kalamos in 1997-2007 indicate the extent of the decline. Red lines are GPS tracks of research vessels closely following common dolphin groups are shown as a proxy of common dolphin relative abundance in the area.
The observed negative trends are not considered a consequence of emigration or long-range movements of common dolphins. This area has been one of the few remaining pockets of high-density occurrence in the central and eastern Mediterranean, and there are virtually no reports of common dolphins in surrounding areas, notwithstanding substantial dedicated effort by several research groups, totalling tens of thousands of kilometres and covering large portions of the eastern Ionian Sea, as well as waters west of the Peloponnese.
Common dolphins appear to be rare in, or absent from, the adjacent central Mediterranean areas explored so far, including the Hellenic Trench, other neritic and pelagic portions of the Ionian Sea, and the Adriatic Sea, the only exception being the inner Gulf of Corinth where a few common dolphins remain.
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Research indicates a high risk of local disappearance of common dolphins in the near future, but also a chance of recovery if appropriate management measures are put in place. |
Encounter rate of large (>80cm) tuna east of Lefkada and around the island of Kalamos, 1997-2007.
To investigate the diet of dolphins around Kalamos and in the Amvrakikos Gulf, scales lost by fish prey were opportunistically collected when predatory events occurred at the surface. Drifting fish scales could be detected visually up to a depth of about 1 m due to shining as they reflected sunlight. Scales were collected by means of a dip net (mesh size 0.4 mm) and preserved into labelled vials with ethanol 80%, each vial containing one or more scales sampled in a given feeding spot.
These scales are being matched with a catalogue of scales from known fish species collected in the study area.
Fish scale of Sardinella aurita seen under a microscope.
Photographs and direct observations of surface foraging by dolphins also contributed to diet investigations.
Bottlenose dolphins catching fish in the Amvrakikos Gulf.
It must be noted that although these methods provide useful insight, they need to be sided by other diet investigation techniques (e.g. stomach content analyses on stranded animals, stable isotope and fatty acid analyses etc.) to account for feeding occurring at depth.
Kalamos area
Since 1997 a total of 80 samples of fish scales drifting at the surface following common dolphin foraging events were collected and stored for diet studies. Fish scales were also collected during surface feeding by other predators (e.g. tuna, swordfish; N=73).
Number of fish scale samples collected around Kalamos between 1997-2008 following surface feeding events
by common dolphins and other high-order marine predators. Sampling opportunities decreased over time
because of the decline of common dolphins and other high-order predators.
Amvrakikos Gulf
Since 2002 a total of 215 samples of fish scales drifting at the surface following bottlenose dolphin foraging events were collected and stored for diet studies.
Number of fish scale samples collected in the Amvrakikos Gulf (2001 - September 2008)
following surface feeding events by bottlenose dolphins.
An alternative method for the investigation of bottlenose dolphin diet in the Amvrakikos Gulf relies on photos of seabirds (mostly seagulls and terns of several species) feeding on prey being schooled and brought to the surface by the dolphins. Seabirds often congregate in the dolphins’ feeding spots and take advantage of surface prey.
Since 2005, birds catching fish near the dolphins are photographed to allow for the visual identification of fish species caught in their beak after successful predatory events.
Terns and seagulls carrying fish schooled to the surface by bottlenose dolphins in the Amvrakikos Gulf.
Dolphins found stranded or floating adrift
Dolphin carcasses stranded or floating adrift were found and investigated throughout the study period. Dolphin strandings are routinely reported to the Greek Ministry of Agriculture and to the Pelagos Cetacean Research Institute, Athens.
Pelagos collects the most valuable skeletal materials and does age determination analyses based on teeth extracted from dead stranded animals.
Around Kalamos, we inspected a total of three common dolphins and four bottlenose dolphins between 1991-2008. Whenever possible, the animals were measured, sexed, inspected and biological samples were taken.
Dolphin carcasses found stranded or adrift around Kalamos between 1991-2008.
In the Amvrakikos Gulf, two dolphins were reported to have stranded near Vonitsa: one in winter 2004-2005, and another in September 2005. A photograph of the former animal confirmed that it was a bottlenose dolphin. However, exact date and location remained unknown. The latter dolphin was reported to have been bycaught in fishing gear, but the animal could not be inspected.
A young male bottlenose dolphin 2.10 m long was found stranded in September 2006. Another adult male 2.57 m long was found in June 2007. In both cases the dolphins were reported by local fishermen. These individuals were measured, sexed and biological samples were taken.
On July 3rd and 4th, 2007, an adult bottlenose dolphin was observed interacting with a dead newborn (probably her own offspring) for several hours. The observations, providing evidence of mourning behaviour, were documented through a total of 532 digital photos taken on the first day, and 138 photos taken on the second day.
On July 3rd, 2008, Tethys researchers observed and filmed the agony of a newborn bottlenose dolphin. The observation lasted about 45 min. The newborn eventually died and sunk in the green murky waters of the Gulf, disappearing from view. The adult dolphins who had been surrounding and assisting the baby left the area. They were followed for about 20 min as they moved away from the place where the newborn had died. Observations were documented by a video and 104 digital photos.
On June 10th, 2008, a Risso’s dolphin was reported stranded on a beach north of Lefkada by Dr. Alexandros Frantzis from the Pelagos Cetacean Research Institute. The precise location was then indicated by Lefkada Coast Guard officers. This individual was measured and sexed. Biological samples were taken and shipped to Dr. Frantzis for further analyses.
Dolphin carcasses found stranded or adrift in the Amvrakikos Gulf and north of Lefkada between (2001 - September 2008). Tt = Tursiops truncatus, Gg = Grampus griseus.
Tissue sampling for genetic and toxicological analyses
Genetic analyses are performed by the University of Durham, U.K.. Hystological and toxicological analyses by the Universities of Padua and Siena, Italy.
Kalamos area
Between 1997 and 2002, a total of 25 skin and/or blubber biopsies were remotely collected from free-ranging individuals: 10 from bottlenose dolphins and 15 from common dolphins. Samples were also obtained from seven animals found stranded in the area: three common dolphins and four bottlenose dolphins.
Amvrakikos Gulf
Between 2001 and 2007, 20 skin biopsies for genetic analyses were remotely collected from bottlenose dolphins by means of the uninvasive “skin swabbing” method. Samples were also obtained from three dead individuals found stranded or floating adrift.
Evidence of dolphin bycatch in fishing gear
Evidence of bycatch and/or entanglement was recorded repeatedly around Kalamos for both common dolphins and bottlenose dolphins.
A total of six strandings have been reported in 2005 in the area of Kalamos, of which one could be documented and involved a mutilated common dolphin. Based on the reported information, the other five events were also likely to involve common dolphins. In all cases the animals were reported to display wounds, knife injuries and mutilations suggestive of bycatch in fishing gear. For instance, one carcass was found eviscerated, bearing longitudinal knife wounds on its belly, that were inflicted to fill the body cavity with stones and sink the animal in a sack, in a failed attempt to prevent it from washing ashore or floating adrift.
A) Carcass of a common dolphin found near Kalamos in August 2005. Fluke lobes were cut off, suggesting a bycatch event. B) Carcass of a bottlenose dolphin found near Kalamos in July 2005. Flukes were cut off, suggesting a bycatch event.
Fishing gear also causes life-threatening lesions in both common dolphins and bottlenose dolphins found in the area of Kalamos, as documented in the following photos.
Examples of entanglement in fishing gear by common dolphins (A, B, C) and bottlenose dolphins (D, E)
photographed around the island of Kalamos.
Other dolphin-fisheries interactions
Kalamos area
Fishery landings in Greece increased until 1994 due to the fleet modernization and geographic expansion of the fisheries over this period. However, declining trends since the mid 1990s suggest that such effects have ceased and fisheries have become unsustainable (Papathanassiou & Zenetos 2005, Stergiou et al. 2007).
Total catch by trophic level in Greek waters, 1950-2000 (from Stergiou et al. 2007).
The combined impact of prey depletion and bycatch in fishing gear around Kalamos is clearly unsustainable for common dolphins, and threatens the small bottlenose dolphin community.
A 12-month assessment of fishing effort and catch, together with circumstantial evidence, suggested that decline of common dolphins was caused largely by prey depletion resulting from overfishing. We analysed the impacts of various fishing gear and estimated the degree of resource overlap between common dolphins and local fisheries. The total biomass removed annually by 308 fishing boats in the study area averaged 3,571 tonnes, while that consumed by common dolphins was 17 tonnes. Resource overlap between common dolphins and fisheries – expressed as an average Pianka index of 0.5 - differed according to fishing gear, being higher for purse seiners (0.7) and beach seiners (0.4) and lower for bottom trawlers (0.1), trammel boats (0.2) and longliners (0.0).
Only about ten active purse seiners (4% of the total active fishing fleet) were responsible for 33% of the biomass removal, and likely had the greatest impact on prey of common dolphins.
Composition of the fishing fleet and number of boats operating east of Lefkada and around Kalamos,
based on a 12-month assessment in 2007 (from Bearzi et al. 2008).
Total fish biomass removed by common dolphins and by fisheries east of Lefkada and around Kalamos in 2007
(from Bearzi et al. 2008). The red part of the fisheries bars shows removal of species representing key prey for common dolphins,
as well as for other top predators such as tuna and swordfish.
Amvrakikos Gulf
Since 2005, contacts with the fishermen operating in the study area were established, and informal meetings were organized. A friendly relationship was developed with local fishermen, which helped gather information that would be difficult to obtain otherwise. Communication with local fishermen allowed to obtain information on the level of conflict between bottlenose dolphins and artisanal fisheries. Direct observations were also conducted from fishing boats.
Ongoing research aims to evaluate the significance of the interactions and quantify the economic loss suffered by artisanal fishermen as a result of conflict.
Monitoring of fish and shell farms
Kalamos area
Fish farms around Kalamos were recorded based on direct observations and/or located through high-definition satellite photos from GoogleEarth (2007). No shell farms exist in this area.
Fish farms around Kalamos are regularly inspected during the surveys, and dolphin activity around fish farm cages are recorded. No interactions were ever observed between common dolphins and coastal fish farms. Conversely, bottlenose dolphins were often seen approaching fish farms and apparently searching for prey in their proximity. This behaviour has been observed with increasing frequency in recent years.
Amvrakikos Gulf
Fish and shell farms in the Amvrakikos Gulf were plotted by recording the GPS position of buoys delimiting the farms. Fish farms in the Gulf totalled approximately 710 fish cages (either for fish of commercial size or hatcheries). A precise count of fish and shell farm numbers is hampered by the difficulty of defining what is a farm unit, considering that most farms are patchy assemblages of a large number of cages (or buoys, as in the case of shell farms). However, about 24 fish farm and five shell farm “clusters” could be counted (shallow-water lagoons were not considered). Gilthead seabream Sparus aurata is the main fish species farmed in the Gulf.
Bottlenose dolphin visits to fish farms are recorded during dedicated fish farm surveys performed on a monthly basis. However, bottlenose dolphin interactions with fish farms appear to be relatively uncommon in the Amvrakikos Gulf.
Position of fish farms (green) and mussel farms (black) around Kalamos (left; highlighted with green circles)
and in the Amvrakikos Gulf (right).
Kalamos area
Large marine species other than common and bottlenose dolphins were observed around Kalamos between 1997-2008.
Cetaceans included an individual fin whale Balaenoptera physalus repeatedly observed in August 2001 and striped dolphins Stenella coeruleoalba (N=3).
Other megafauna included Mediterranean monk seals Monachus monachus (N=13), billfish (N=102; most likely swordfish Xiphias gladius), Mediterranean spearfish Tetrapturus belone (N=2), devil fish Mobula mobular (N=44), ocean sunfish Mola mola (N=3), and unidentified shark species (N=8). Scombridae estimated visually to be longer than approximately 80 cm were regularly recorded as “tuna” (N=70). This category included mostly or exclusively northern bluefin tuna Thunnus thynnus and albacore Thunnus alalunga spotted at the surface when they were feeding.
Sightings and findings of loggerhead sea turtles Caretta caretta during the surveys at sea were systematically recorded. A total of 32 living turtles and 2 dead turtles were encountered around Kalamos between 1991 and 2008.
Amvrakikos Gulf
Cetacean species other than bottlenose dolphins were never seen in the Gulf. Marine predators such as monk seals and large predatory fish or elasmobranchs also were never encountered during surveys at sea.
On 23 March 2008 a 170 cm female sandbar shark Carcharhinus plumbeus was bycaught in the gillnet of a local fishermen within the Amvrakikos Gulf. This specimen, captured still alive, was sold the day after by a fishmonger in Vonitsa. Details on this event were sent to shark expert Eleonora de Sabata, member of the IUCN Shark Specialist Group.
A total of 139 sightings of pelicans were recorded: 10 in 2005, 26 in 2006, 46 in 2007 and 45 between January and September 2008. These included the white pelican Pelecanus onocrotalus and possibly the endangered Dalmatian pelican Pelecanus crispus, a rare species which colonies are known to nest in the area. Pelicans were photographed whenever possible to allow for species identification by bird specialists.
Other unusual bird species recorded during the surveys included Cory’s shearwater Procellaria diomedea, Manx shearwater Puffinus puffinus), herons (especially the grey heron Ardea cinerea, often seen in the proximity of fish farms), great white egrets Egretta alba, little egrets Egretta garzetta, one black-winged stilt Himantopus himantopus, kingfishers Alcedo atthis, unidentified Anatidae and several other unidentified bird species. A flying flock of greater flamingoes (Phoenicopterus ruber) including about 100-200 individuals was observed in September 2005 in the western part of the Gulf.
Seagulls and terns of various species were especially abundant throughout the Gulf, and consistently associated with dolphins during surface foraging. Cormorants were seen in large quantities in winter months.
Birds interacting with dolphins during surface foraging and other activities are routinely photographed. This will allow future analyses on the bird species involved and on the seasonality and pattern of interactions.
Sightings and findings of loggerhead sea turtles Caretta caretta during the surveys at sea were systematically recorded. A total of 315 living turtles and 12 dead turtles were encountered in the Amvrakikos Gulf between 2001 and September 2008.
All photos, maps, graphs and text in this report © Tethys Research Institute.
Animal drawings © Massimo Demma.