The Tethys Research Institute was founded in Milan, Italy, on 31 January 1986 by marine ecologist Giuseppe Notarbartolo di Sciara[1] and Egidio Gavazzi, at the time the publisher of the italian magazine AQVA.

Since its foundation, Tethys has promoted research activities on marine mammals, such as cetaceans (whales and dolphins) and the endangered Mediterranean monk seal, although investigations have also extended to devil rays and sea turtles.

Tethys shares its data with the scientific community and policy makers through several open access platforms such as OBIS, OBIS-SEAMAP, GBIF, EMODNET, and INTERCET.

A study financed by the Permanent Secretariat of the Pelagos Agreement and published in September 2020 (Proposal to develop and evaluate mitigation strategies to reduce the risk of ship strikes to fin and sperm whales in the Pelagos Sanctuary) was carried out in collaboration with British Antarctic Survey, International Fund for Animal Welfare, QuietOceans, Souffleurs d'Ecume, WWF France.

The project focuses on population dynamics, spatial distribution, habitat preferences, behaviour,  bioacoustics, photogrammetry, genetics, as well as on the evaluation of long-term environmental changes and monitoring of anthropogenic pressures.

Studies conducted within the CSR project generated one of the longest time series and one of the largest datasets on Mediterranean cetaceans, allowing to evaluate and detect changes in the species’ presence.

Cetaceans’ vocalisations are regularly recorded, generating a large acoustic dataset and allowing studies of the vocal repertoire of sperm whales and other species.

Research on cetaceans in the Pelagos Sanctuary also revealed an unexpected genetic separation between fin whales occurring in the Ligurian Sea and their North Atlantic conspecifics.

[16] The long-term photo-identification study of fin whales in the Pelagos Sanctuary (1990–present) points to the existence of a persistent site fidelity and reaffirms the importance of this area as a major feeding ground and critical habitat for the Mediterranean subpopulation, providing baseline data for targeted conservation and mitigation measures.

Satellite tracking also revealed that the feeding habitat of fin whales extends substantially to the West of the Pelagos Sanctuary’s boundaries, well into the Gulf of Lion and into Spanish waters.

[19] A pilot project aimed at investigating the potential use of a medium fixed-wing aircraft system (RPAS) for monitoring cetaceans, as an alternative method to conventional aerial manned surveys, was launched in 2022.

Thanks to a long-lasting collaboration with the Italian Coast Guard, the RPAS, provided by the REACT consortium on behalf of the European Maritime Safety Agency EMSA, was also tested during a preliminary survey in an area within the Pelagos Sanctuary.

Since the early years, the project has also expanded its geographic coverage and nowadays the research is concentrated in three Natura 2000 study areas of Western Greece: the Gulf of Ambracia, the Inner Ionian Sea Archipelago and the Paxos and Antipaxos Islands and surrounding waters.

In the Inner Ionian Sea Archipelago site (Natura 2000 code GR2220003)[20] [21] common dolphins dramatically declined  between 1995 and 2007, which has been convincingly linked to overfishing, although impact resulting from an ever-increasing nautical tourism should not be ruled out.

The IDP has gathered strong evidence that some distinctive areas provide key monk seal breeding habitats that appear to be of great importance for the conservation of the species on a Mediterranean scale.

The main threats faced by this endangered species in the Inner Ionian Sea Archipelago derive, to a large extent, from disturbance by boat-based tourism, and possibly also from negative interactions with fishing activities.

In the semi-enclosed, highly degraded, Gulf of Ambracia (Natura 2000 code GR2110001) [22] the IDP studies a resident population of 150 common bottlenose dolphins that display a unique behaviour and ecology.

Data gathered in these years showed that bottlenose, common and striped dolphins are regularly present, and monk seals are occasionally sighted around the numerous caves in the western side of Paxos island.

[30] With the support of the European Association Rotary for the Environment, and in collaboration with the NGO Europe Conservation, on 2 March 1991 Tethys presented the "Pelagos Sanctuary" idea to H.S.H.

The First Mediterranean Region Important Marine Mammal Areas IMMA Workshop, held in Chania, Crete (Greece), 24–28 October 2016, was organised by Tethys in cooperation with ACCOBAMS.

Other communication initiatives were: ●      “Digital Whales” (September 2019 - December 2020), an augmented-reality project at the Civic Aquarium of Milan, launched together with Verdeacqua, and funded by Fondazione Cariplo.

The objective was to build an international strategic partnership to enhance research and education in the subject of sustainable marine management and communication strategies, within the Mediterranean unique natural and socio-economic context.