Presentation

The Ionian Dolphin Project is a long-term research and conservation programme conducted by the Tethys Research Institute in the Ionian Sea.

In 1991 the Tethys Research Institute started a study in the Inner Ionian Sea Archipelago (a Natura 2000 area). 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 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 - which is part of a larger National Park - is also inhabited by loggerhead sea turtles 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 2009 Tethys started a new study in the Gulf of Corinth to investigate the ecology and status of three cetacean species: bottlenose dolphins, striped dolphins and common dolphins. While the number of striped dolphins living in the Gulf is still unknown, concerns over their status are raised by their high degree of geographic isolation, reproductive closeness and limited extent of occurrence. Striped dolphins in the Gulf are often associated with a few common dolphins and inbreeding between the two species may occur. Bottlenose dolphins also live in the Gulf at low densities.

Research by Tethys is providing support to dolphin conservation efforts in the 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 and identify critical habitat;

• research on factors threatening the local ecosystems, particularly excessive fishing;

• public awareness, education and capacity building initiatives (e.g. involvement of a large number of students and volunteers, dolphin events organised locally, public presentations, lectures at local schools, production of multimedia);

• contacts and meetings with the local Authorities and fishermen organisations, aimed to raise awareness on the need of establishing measures to protect dolphins and implement existing regulations (e.g. to prevent illegal fishing);

• 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 Inner Ionian Sea Archipelago was proposed as Marine Protected Area at the 3rd Meeting of the Parties to the UNEP/CMS Agreement on the Conservation of Cetaceans of the Black Sea, Mediterranean Sea and contiguous Atlantic Area (ACCOBAMS). The Scientific Committee of ACCOBAMS also recommended the Parties to consider the Amvrakikos Gulf as a candidate MPA. Both candidatures were based on evidence provided by Tethys.

The Ionian Dolphin Project by numbers

19 years of dolphin research: 1991-2009 (ongoing)

104,358 km of survey effort

1,507 dolphin sightings

29,387 samples of dolphin behaviour

78,585 selected dolphin photographs

About 700 individual dolphins photo-identified (three species)

About 90 scientific contributions

Study areas

The Ionian Dolphin Project study areas and field stations.

The Inner Ionian Sea Archipelago is situated in eastern Ionian Sea coastal waters. It 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, oligotrophic and unaffected by significant river and agricultural runoffs. The main anthropogenic threat to marine biodiversity in this area is represented by overfishing.

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, eutrophic and strongly affected by runoff from the two rivers Louros and Arachthos. Concern over the long-term status of the Gulf and its biodiversity os raised by increasing eutrophication and pollution.

The Gulf of Corinth (approximately 2,400 km2 wide) is a semi-closed basin of extraordinary interest and one of the eight proposed Marine Protected Areas for cetaceans recommended by ACCOBAMS for the conservation of whales and dolphins in the Mediterranean Sea. The Gulf is a deep inlet of the Ionian Sea separating the Peloponnese from western mainland Greece. The Strait of Rion, crossed by the Rio-Antirio bridge, separates the Gulf of Corinth from the outer Gulf of Patras. Waters up to almost 1,000 m deep are found relatively close to the coast, so that pelagic species such as the striped dolphin are found nearshore. Its oligotrophic and transparent waters, unaffected by significant river or agricultural runoffs, are exposed to anthropogenic pressures including unregulated discharge of toxic contaminants.

Tethys also does research on cetaceans in the Ionian Sea and Adriatic waters of south-east Italy (Apulia), not described in this report. Please click here to know more about dolphin research in Apulia.

Target species

Common bottlenose dolphin Tursiops truncatus

Bottlenose dolphins, the most coastal species in the Mediterranean Sea, have been negatively affected in numerous ways by human activities. Until the 1960s, they have been one of the main targets of culling campaigns, resulting in thousands of animals killed. In recent times, incidental mortality in fishing gear, prey depletion caused by overfishing, habitat degradation, boat traffic, noise, and health effects caused by pollution are important threats. Mediterranean bottlenose dolphins have been proposed for classification as Vulnerable in a recent Red List assessment by IUCN.

A relatively stable presence of bottlenose dolphins was observed in the Inner Ionian Sea Archipelago. About 25 animals have shown high levels of site fidelity over the past decade, while other individuals 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 are resident within the Gulf. Population size is about 150 individuals, a relatively high density. However, the Gulf is facing increasing eutrophication and chemical pollution, resulting in ecosystem changes. Notwithstanding their abundance, bottlenose dolphins living in the Amvrakikos Gulf are highly isolated into a restricted habitat and would qualify as Vulnerable in the IUCN Red List.

Bottlenose dolphins are one of the three cetacean species living in the Gulf of Corinth, where they are present at low densities. Their extensive movements may reduce problems deriving from small population size, such as inbreeding. Long-range movements in and out of the Gulf, encompassing about 200 km of coastline, were documented by Tethys in 2009, suggesting that the local bottlenose dolphins may be part of an open and highly mobile population.

Short-beaked common dolphin Delphinus delphis

Once one of the most abundant cetacean species in the Mediterranean Sea, common dolphins have declined throughout the region during the last 30-40 years. In 2003 their Mediterranean population was classified as Endangered in the IUCN Red List. In 2006 they were included in Appendix I and II of the Convention on the Conservation of Migratory Species (Bonn Convention - CMS). The causes of their generalised decline remain poorly understood but are thought to include prey depletion and bycatch.

In 2004 ACCOBAMS produced a Conservation Plan for Mediterranean common dolphins, where the Inner Ionian Sea Archipelago (a Natura 2000 Site of Community Importance under the EU Habitats Directive) was identified as area of high conservation importance fort common dolphins. The importance of this area 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 has declined dramatically, from 150 animals in 1995 to only 15 animals in 2007. Such decline was linked to prey depletion resulting from intensive exploitation of the local fish stocks.

The few common dolphins living in the Gulf of Corinth, possibly the survivors of a formerly larger population, are always found in association with the more abundant striped dolphins. Such association may be an adaptive behaviour developed by the last common dolphins to maintain social bonds and enjoy the benefits of living in groups. While inbreeding between the two species may occur, it remains to be conclusively documented. The future of common dolphins in the Gulf of Corinth appears gloomy due to the small number of individuals left in the area and their high degree of geographic isolation.

Striped dolphin Stenella coeruleoalba

Striped dolphins are 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 scarcity. Striped dolphins are also exposed to high levels of mortality in fishing gear, particularly pelagic gillnets.

The population of striped dolphins living in the eastern Gulf of Corinth is apparently isolated from the rest of the Mediterranean Sea. An unknown number of striped dolphins survive in the inner part of the Gulf, but concerns over their status and extinction risk are raised by the animals’ high degree of geographic isolation, reproductive closeness and limited extent of occurrence. Striped dolphins in the Gulf of Corinth are often found in association with small numbers of short-beaked common dolphins.

Overview of methods

Surveys to monitor dolphins in the Ionian Sea areas are conducted from inflatable boats with fibreglass keels, normally between April and October.

Individual photo-identification is used to catalogue dolphins of three different species and obtain information on their abundance, movements, habitat use, social organisation and reproductive success.

The group size and behaviour of the dolphins is recorded during long-lasting observation sessions and 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 are subsequently analysed to identify the dolphin's prey species.

Marine species including sea turtles, monk seals, tuna, mobulas, swordfish and seabirds observed during the surveys at sea are recorded. Dead dolphins 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 bycatch in fishing gear is also recorded.

The project includes investigations aimed to assess the interactions between dolphins and local fisheries.

Survey effort

Surveys to monitor dolphins in the Inner Ionian Sea Archipelago 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.

Research effort in the Inner Ionian Sea Archipelago and in the Gulf of Corinth is normally conducted in the warm season and covers 5 to 7 months per year.

Research in the Amvrakikos Gulf was carried out year-round between April 2006 and December 2008. Since 2009 the field work is done from April to October.

The Inner Ionian Sea Archipelago dataset, 1991 - 2009

Data in the Inner Ionian Sea Archipelago were collected during a total of 91 months spent in the field across 19 years of research, totalling 1,892 hours spent with 1,762 dolphin groups.

A total of 1,252 daily surveys were conducted between 1991 and 2009. The navigation effort totalled 72,607 km. Across 19 years, 502 sightings of common dolphins and 447 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 (2002-2009). Individual dive intervals were also timed between 1996-1999. A total of 23,505 record units (“samples”) of behaviour were recorded: 8,751 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 5,435 of bottlenose dolphins were timed to investigate dolphin surfacing patterns and feeding behaviour.

Routes surveyed under favourable conditions (“on effort”) in the Inner Ionian Sea Archipelago in years 1991-2009.
Multiple coverage of pre-defined survey transects appear as a single line.

Summary of research effort in the Inner Ionian Sea Archipelago (1991-2009). Dd = Delphinus delphis, Tt = Tursiops truncatus.

The Amvrakikos Gulf dataset, 2001 – 2009

Data in the Amvrakikos Gulf were collected during a total of 54 months spent in the field over 9 years of research, totalling 684 hours spent with dolphins.

A total of 556 daily surveys were conducted between 2001 and 2009. The navigation effort totalled 24,889 km and resulted in 500 sightings of bottlenose dolphins, and 408 of loggerhead turtles.

Since 2005 dolphin behaviour was sampled based on 5 min observation intervals. A total of 5,237 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 643 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 (2002-2009).
Multiple coverage of pre-defined survey transects appear as a single line.

Summary of research effort conducted in the Amvrakikos Gulf (2001-2009).
Tt = Tursiops truncatus, Cc = Caretta caretta.

The Gulf of Corinth dataset, 2009

Data in the Gulf of Corinth were collected during a total of 6 months spent in the field over one year of research, totalling 67 hours spent with dolphins.

A total of 96 daily surveys were conducted between April and September 2009. The navigation effort totalled 6,862 km and resulted in 25 sightings of bottlenose dolphins, and 33 of mixed striped/common dolphin groups.

Dolphin behaviour was sampled based on 5 min observation intervals. A total of 645 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.

Routes surveyed under favourable conditions (“on effort”) in the Gulf of Corinth (April-September 2009).
Multiple coverage of pre-defined survey transects appear as a single line.

Summary of research effort conducted in the Gulf of Corinth (April-September 2009).
Tt = Tursiops truncatus, Dd = Delphinus delphis, Sc = Stenella coeruleoalba.

Dolphin encounters

The following figures show the initial positions of dolphin sightings, and dolphin movements in the study area in the Inner Ionian Sea Archipelago, in the Amvrakikos Gulf and in the Gulf of Corinth.

Initial position of sightings (blue dots) and movements (blue lines) of bottlenose dolphins and common dolphins (green triangles, green lines) in the Inner Ionian Sea Archipelago in years 1991-2009.

Initial position of sightings (blue dots) and movements (blue lines) in the Amvrakikos Gulf in years 2001-2009.
Only one sighting was made in the open waters facing the Gulf, out of 667 km of survey effort under favourable conditions.

Initial position of sightings (blue dots) and movements (blue lines) of bottlenose dolphins and striped/common dolphins (red triangles, red lines) in the Gulf of Corinth (April-September 2009).

Photo-identification

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 1991-2009 included 78,585 photos on which photo-identification and other analyses were performed.

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, bottlenose dolphins and striped dolphins living in the three study areas.

Number of selected dolphin photos taken in the Inner Ionian Sea Archipelago, in the Amvrakikos Gulf and in the Gulf of Corinth in years 1991-2009.
Tt = Tursiops truncatus, Dd = Delphinus delphis, Sc = Stenella coeruleoalba. NC = not computed.

Dorsal fins of two well-marked bottlenose dolphins.

Dorsal fins of striped dolphins. Between April and September 2009, about 250 different individuals have been photo-identified in the Gulf of Corinth based on long-term natural markings on their dorsal fins.

Screen capture of one of the database programmes used for dorsal fin analyses.

Residency patterns of 165 common dolphins identified in the Inner Ionian Sea Archipelago between 1993 and 2008, based on long-term natural marks on their dorsal fins.  In 2009 there were no sightings of common dolphins.

Residency patterns of 101 bottlenose dolphins identified in the Inner Ionian Sea Archipelago between 1993 and 2009,
based on long-term natural marks on their dorsal fins.

Residency patterns of 151 bottlenose dolphins identified in the Amvrakikos Gulf between 2001 and 2009, 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 the Publications section) and is not reported here.

The most impressive information recorded over the years concerns the dramatic decline of common dolphins in the Inner Ionian Sea Archipelago. 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 in the Inner Ionian Sea Archipelago, this area still represents important habitat and the surviving common dolphins that have been spreading over a larger region may be able to recolonise if appropriate management measures are put in place.

Abundance trend of common dolphins in the Inner Ionian Sea Archipelago in 1995-2007.

Occurrence patterns of common dolphins in the Inner Ionian Sea Archipelago 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.

Sightings of large tuna also declined dramatically in the Inner Ionian Sea Archipelago between 1997 and 2007.

Encounter rate of large (>80cm) tuna in the Inner Ionian Sea Archipelago, 1997-2007.

	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.

Dolphin feeding ecology

To investigate the diet of dolphins in the Inner Ionian Sea Archipelago 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.

Scales of Sardinella aurita as seen under a microscope (© Zsuzsanna Pereszlényi / Tethys Research Institute).

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.

Inner Ionian Sea Archipelago

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 in the Inner Ionian Sea Archipelago between 1997 and 2009 following surface feeding events by common dolphins and other high-order marine predators. Sampling opportunities decreased over time due to decline of common dolphins and other high-order predators.

Amvrakikos Gulf

Since 2002 a total of 263 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 (2002-2009) 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 carrying fish schooled to the surface by bottlenose dolphins in the Amvrakikos Gulf.

Based on fish scale analyses, two species of sardines - European pilchard and round sardinella - were identified as targets by local dolphins. Contrary to other Mediterranean areas, where bottlenose dolphins focus on demersal prey and rarely target small epipelagics, in the Amvrakikos Gulf surface feeding was found to represent an important part of the dolphin’s daily activity, and sardines an important prey item. The local bottlenose dolphins therefore seem to have developed a highly specialised foraging behaviour determined by prey availability and local conditions.

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.

In the Inner Ionian Sea Archipelago, we inspected a total of three common dolphins and four bottlenose dolphins between 1991 and 2009. Whenever possible, the animals were measured, sexed, inspected and biological samples were taken.

Dolphin carcasses found stranded or adrift in the Inner Ionian Sea Archipelago between 1991 and 2009.
Tt = Tursiops truncatus, Dd = Delphinus delphis.

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.

On September 7th, 2009, a male bottlenose dolphin of 2.70 m was reported stranded near Vonitsa, and inspected by Tethys researchers on the following day. The animal was apparently of old age, based on worn teeth. He showed no sign that could indicate the cause of death.

Dolphin carcasses found stranded or adrift in the Amvrakikos Gulf and north of Lefkada between 2001 and 2009.
Tt = Tursiops truncatus, Gg = Grampus griseus.

In the Gulf of Corinth, on May 18th, 2009, an adult bottlenose dolphin was observed carrying a dead newborn, possibly her offspring. The presumed mother was observed for a total of two hours, consistently carrying the decomposing corpse on her back, in front of the dorsal fin, also performing dives and resurfacing with the newborn in the same position. Occasionally the dead newborn was pushed and carried underwater with the rostrum. Other dolphins were seen in the area during the observation, but they tended to stay away from the couple. The presumed mother was photo-identified based on long-term natural marks on her dorsal fin. On the following day (May 19th) she was sighted again in the same area in the company of another adult, but without the dead newborn. These observations were documented by approximately 200 digital photos.

Tissue sampling for genetic and toxicological analyses

Genetic analyses were performed by the University of Durham, UK. Hystological and toxicological analyses by the Universities of Padua and Siena, Italy.

Inner Ionian Sea Archipelago
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. No samples were collected after 2002.

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. No samples were collected after 2007.

Gulf of Corinth
No tissue samples were collected in 2009.

Evidence of bycatch and/or entanglement was recorded repeatedly in the Inner Ionian Sea Archipelago for both common dolphins and bottlenose dolphins.

A total of six strandings have been reported in 2005 in the Inner Ionian Sea Archipelago, 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

B

A) Carcass of a common dolphin found near the island of 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 Inner Ionian Sea Archipelago, as documented in the following photos.

Examples of entanglement in fishing gear by common dolphins (A, B, C) and bottlenose dolphins (D, E) photographed in the Inner Ionian Sea Archipelago.

Other dolphin-fisheries interactions

Inner Ionian Sea Archipelago

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 in the Inner Ionian Sea Archipelago 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 in the Inner Ionian Sea Archipelago, based on a 12-month assessment in 2007 (from Bearzi et al. 2008).

Total fish biomass removed by common dolphins and by fisheries in the Inner Ionian Sea Archipelago 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 organised. 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.

Inner Ionian Sea Archipelago
Fish farms in the Inner Ionian Sea Archipelago 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 in the Inner Ionian Sea Archipelago were regularly inspected during the surveys, and dolphin activity around fish farm cages 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. 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.

Gulf of Corinth
Fish farms in the Gulf of Corinth started to be plotted in 2009 by recording the GPS position of buoys delimiting the farms. Fish farms situated in the Bay of Itea were regularly inspected, and dolphin activity around fish farm cages recorded. Bottlenose dolphins were seen occasionally approaching fish farms and searching for prey in their proximity, for relatively short periods of time. No interactions were observed between common dolphins or striped dolphins and coastal fish farms.

Other marine species

Inner Ionian Sea Archipelago

Large marine species other than common and bottlenose dolphins were observed around Kalamos between 1993 and July 2009. 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=12), billfish (N=129; most likely swordfish Xiphias gladius), Mediterranean spearfish Tetrapturus belone (N=2), devil fish Mobula mobular (N=40), ocean sunfish Mola mola (N=6), and unidentified shark species (N=12).

Scombridae estimated visually to be longer than approximately 80 cm were regularly recorded as “tuna” (N=79). This category included mostly or exclusively northern bluefin tuna Thunnus thynnus and albacore Thunnus alalunga spotted at the surface when they were feeding.

A total of two dead loggerhead sea turtles were found floating adrift in the Inner Ionian Sea Archipelago between 2001 and 2009.

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 150 sightings of pelicans were recorded: 10 in 2005, 26 in 2006, 46 in 2007, 47 in 2008 and 21 in 2009. 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.

Loggerhead sea turtles were frequently sighted at sea in the Amvrakikos Gulf (N=391). In addition, a total of 17 dead loggerhead sea turtles were found floating adrift between 2001 and 2009.

Gulf of Corinth

Between April and September 2009, marine megafauna encountered in the Gulf of Corinth included: loggerhead sea turtles Caretta caretta (N=11), ocean sunfish Mola mola (N=2), billfish (N=6; most likely swordfish Xiphias gladius) and scombridae estimated visually to be smaller than approximately 80 cm (N=35) spotted at the surface while feeding.

In addition, a total of three dead loggerhead sea turtles were found floating adrift in the Gulf of Corinth in 2009.

Ionian Dolphin Project videos

		Disappearing Dolphins (17 min 26 sec) A video documentary by EarthOcean featuring the efforts of Ionian Dolphin Project researchers to study and protect dolphins in western Greece. Language: English - Spanish - French - Italian - German - Greek - Arabic
		DolphinPeople (13 min 24 sec) A story featuring the work of three Ionian Dolphin Project researchers. Language: Italian, English subtitles.
		Mediterranean Coastal Dolphins (3 min 34 sec) A short video on the decline of coastal dolphins in the Mediterranean Sea. Language: English.

Blogs

Ionian Dolphins
The Blog of the Ionian Dolphin Project
http://ioniandolphins.blogspot.com/

Dolphins in a Bottle
A Blog featuring dolphin research in the Amvrakikos Gulf
http://dolphinsinabottle.blogspot.com/

Tethys News
The Blog of the Tethys Research Institute
http://istitutotethys.blogspot.com/

More about the Ionian Dolphin Project

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All photos, maps, graphs and text in this report © Tethys Research Institute.

Animal drawings © Massimo Demma.