Dolphins inhabiting the coastal waters of Greece are facing significant threats. Some dolphin populations must deal with increasing human encroachment, while others have disappeared altogether from portions of their former range.
The Ionian Dolphin Project aims to ensure the long-term viability of dolphins species living in coastal waters of the eastern Ionian Sea. Research by Tethys Research Institute is providing support to dolphin conservation efforts, 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 delivery of management proposals to international agreements and bodies concerned with the protection of marine biodiversity.
The coastal waters of Greece still harbour a remarkable diversity of cetacean fauna compared to other parts of the Mediterranean. Yet, such richness is decreasing due to degradation of the marine environment. Research and conservation activities conducted in the context of the IDP are identifying measures to slow-down, halt or reverse such trends.
While today’s abundance of dolphins is likely only a fragment of what it was a century ago, important populations still live and reproduce in the Greek seas. Ensuring the long-term survival of healthy dolphin populations must become a priority, as advocated by the EC Habitats Directive and the Marine Strategy Framework Directive and consistent with national commitments to preserve cetaceans and marine biodiversity.
Common bottlenose dolphin (Tursiops truncatus)
Bottlenose dolphins, the most coastal cetacean 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.
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 since the 1960s. In 2003 their Mediterranean population was classified as Endangered in the IUCN Red List. In 2006 they have been included in Appendix I and II of the Convention on the Conservation of Migratory Species (Bonn Convention – CMS). The causes of their generalised decline include prey depletion by overfishing and incidental mortality in fishing gear.
The IDP research activities are carried out primarily in two study areas, which are remarkably diverse in terms of environmental features and threats posed by human activities, therefore offering opportunities for understanding the links between dolphin status and habitat quality in different situations.
Area 1) Inner Ionian Sea archipelago
In 1991 the Tethys Research Institute began a study in the Inner Ionian Sea archipelago, a Natura 2000 area. Initially intended to be a long-term investigation on the ecology and behaviour of common dolphins in a central Mediterranean hotspot, the study instead became a documentation of their sharp decline.
Common dolphins in this area declined dramatically from approximately 150 to 15 animals between 1995 and 2007. Since then, a few sightings have been reported in the adjacent waters. Monitoring done in subsequent years (2008-2011) showed that a few animals are still present and they likely roam across a much wider area, occasionally moving into their former wonderland. A number of calls were made by several marine conservation organisations to facilitate their recovery, to no avail. Decline of common dolphins in this area has been convincingly linked to overfishing and specific fisheries management solutions have been advocated.
Bottlenose dolphins are found in relatively small numbers, but they seem to have stable trends. Of about 120 individuals photo-identified in this area, about one quarter have shown high levels of site fidelity, while the others are transients. However, even individuals with high levels of ‘residency’ were found to make long-distance movements.
Groups of striped dolphins occasionally enter these waters.
Area 2) Amvrakikos Gulf
In 2001 Tethys started a study in the Amvrakikos Gulf, where bottlenose dolphins are the only cetacean species encountered. Ongoing research showed that roughly 150 dolphins inhabit the Gulf. These dolphins are members of a highly ‘resident’ community, displaying unique behaviour and ecology. A few individuals photo-identified in the Amvrakikos Gulf were subsequently observed in the Inner Ionian Sea archipelago and in the Gulf of Corinth, but no immigration into the Gulf was recorded so far.
Research carried out by Tethys is documenting how the local dolphin community interacts with its environment and how human activities may influence its conservation status.
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. The Gulf’s biodiversity, however, is threatened by high and increasing eutrophication and pollution.