Tethys has conducted research to define threats and contribute to cetacean conservation in the Mediterranean Sea and elsewhere since 1986.
Some of the most important research projects are listed below.
Please note that research conducted after 1998 may not be included here.
Rescue and rehabilitation of the Mediterranean monk seal in Italy
A feasibility study was conducted under contract from the Italian Ministry of Agriculture and Forestry, for the construction of a research, rescue and rehabilitation facility for stranded and orphaned monk seals (Monachus monachus) in northern Sardinia.
Cetacean ecology in the central Mediterranean Sea
A series of research cruises were conducted in order to assess distribution and relative sighting frequency of cetacean species in the central Mediterranean Sea. The seas surrounding the Italian peninsula were stratified in 7 regions and the cetacean distribution among them was investigated. Results showed that the Ligurian Sea, due to the peculiar hydrographic and oceanographic features was characterised by an outstanding high abundance of cetofauna with respect to the other seas. Specifically, fin whales (Balaenoptera physalus) and striped dolphins (Stenella coeruleoalba) were the most common pelagic species, while Risso's dolphins (Grampus griseus) were predictably encountered along the steep continental shelf. Striped dolphins were also frequently found in all other pelagic areas. Common dolphins (Delphinus delphis) were encountered rarely, and especially where the continental shelf protrudes far from the coast. Bottlenose dolphins (Tursiops truncatus), typically inhabiting the coastal waters, were the only species sighted in the northern Adriatic Sea.
Bioacoustics of Mediterranean cetaceans
From its foundation Tethys has pioneered studies on cetacean bioacoustics in the Mediterranean Sea. Numerous institutions and organisations have cooperated with Tethys in order to shed light about vocal habits and the nature of cetacean acoustic behaviour in Mediterranean waters: among these were from the early years Woods Hole Oceanographic Institution, Saclantcen/ASW-Centre, and the University of Pavia; in more recent years a number of governmental (such as DOP-Univ. Azores, UC Santa Cruz, ICRAM-Rome, Oxford Univ.) and non-governmental organisations (such as IFAW, Alnitak, Greenpeace, Europe Conservation, CESVI) have become frequent partners in cooperative efforts to solving specific issues related to most diverse applied subjects such as ocean acoustics, acoustic disturbance, whale-watching, cetacean acoustic censusing, fisheries acoustics and conservation. A collection of sound recordings from as many as 12 different cetacean species from the Mediterranean as well as from the Atlantic and Indian Oceans are preserved at Tethys for scientific and educational use. Scientific consultancies have been carried out in the Mediterranean Sea, in the Caribbean Sea, in the Eastern Atlantic Ocean, in the Eastern Pacific and in the Eastern Indian Ocean as well as in tropical riverine and estuarine environments (Thailand, Laos). Tethys is at present involved in a number of national and international cooperative acoustic projects, such as: 1) fin whale acoustic ecology in the Mediterranean, 2) acoustic censusing of Odontocetes in the Ligurian Sea Sanctuary area, 3) acoustic assessment of cetaceans in the Azores, 4) acoustic assessment of long-finned pilot whales (Globicephala melas) of the western Mediterranean and the Sea of Alboran, 5) acoustic behavioural studies on the Risso's dolphin (Grampus griseus) in the Ligurian Sea Sanctuary area, 6) a pilot study on the acoustics of the irrawaddy dolphin (Orcaella brevirostris) in the Mekong of Laos PDR, and 7) sperm whale (Physeter macrocephalus) ecology in the western Mediterranean Sea.
Adriatic Dolphin Project
The Adriatic Dolphin Project is a long-term study aimed at providing an overall picture of the population status of the bottlenose dolphin (Tursiops truncatus) in Croatian waters. Distribution and abundance, population structure and status, habitat use, feeding habits and impact of human activities are investigated in order to provide information for a rational conservation and management. The knowledge obtained through a multidisciplinary approach - which takes into account the complex links among any species, its environment and other living components of the ecosystem - will have clear implications for conservation and management in this area.
In 1997 the Adriatic Dolphin Project became a cooperative research programme between Tethys and the Natural History Museum of Zagreb.
The main bottlenose dolphin community under study includes 100-120 individuals. The majority of them show a high rate of site fidelity. Group composition is variable, with the most common group composed by two dolphins, with an average of seven individuals. Not surprisingly groups with calves are the largest. Compared to the situation of other bottlenose dolphins population (for example, Australia and California), here there is no evidence of a strict sexual segregation, most groups being apparently mixed. The social organisation of this dolphin community seems to be highly flexible, possibly as an adaptation to cope with environmental changes as well as with a variable availability of prey.
Diurnal behavioural data showed a striking predominance (about 80%) of activities considered to be largely related to prey search or feeding. The frequent following of trawlers is indicative of the presence of alternative strategies for finding food. Wide yearly and seasonal variations in feeding-related behaviours seem to reflect opportunistic rather than regular patterns, indicative of a behavioural flexibility to face environmental changes and fluctuating prey kind and availability.
Other cetacean species - as common and striped dolphins - were rarely observed in the main study area. All observations related to a very small number of stray individuals. This reflects the almost complete disappearance of common dolphins from the Northern Adriatic Sea, a region in which both bottlenose dolphins and common dolphins were historically abundant.
Fin whale radio-tagging
A dedicated research cruise was organised in co-operation with the Woods Hole Oceanographic Institute (Massachusetts, USA) in order to investigate the ecology and movement patterns of fin whales on their summer feeding grounds in the Ligurian Sea. Whales were tagged with remotely-implanted radio-transmitters and tracked from vessels using VHF signals.
Scientific coordination of Greenpeace's "Operazione Cetacei"
A public awareness initiative promoted in Italy by Greenpeace, to enhance conservation of cetaceans in the Italian seas, was supported by the Tethys Research Institute by providing scientific advice on the organisation of sighting campaigns, and lectures at gatherings of interested participants.
Mediterranean Fin Whale Project
Toxicology of Mediterranean cetaceans
Marine vertebrates, and especially mammals, are typical endpoints of the biomagnification processes of persistent contaminants of the marine food web. This critical position exposes them to toxicological risks. Whales and dolphins accumulate heavy metals and organochlorines in their tissues: these xenobiotics are considered as responsible of immunological disorder in marine mammals. Therefore, it is of foremost importance to investigate the health status of marine mammals and to give of them a clear ecotoxicological assessment. These data may contribute to the evaluation of environmental quality and provide criteria for conservation measures. In the context of a long-term collaboration with the Tethys Research Institute, toxicological studies on marine mammals have been carried on by the Department of Environmental Biology, University of Siena (Italy), by the use of biomarkers and residue analysis. Biomarkers (xenobiotically induced variations in cellular or biochemical components, processes, structures or functions) can indicate the magnitude of the organism's response to contaminants as well as provide the causal link between the presence of a chemical and an ecological effect. The information derived from biomarker studies represent a powerful tool for risk assessment of wild animal population.
Skin biopsies including subcutaneous blubber from fin whales (Balaenoptera physalus), striped dolphins (Stenella coeruleoalba), bottlenose dolphins (Tursiops truncatus) and common dolphins (Delphinus delphis) were sent to the Department of Environmental Biology for chemical and biochemical analysis. Polychlorinated biphenyls (PCBs) and DDT compounds were determined in subcutaneous blubber, mixed function oxidase (MFO) activity and DNA damage in skin. Porphyrins have been detected in faeces. Particularly interesting was the result of the residues analysis and the benzo(a)pyrene monooxigenase (BPMO) activity in fin whales and striped dolphins. These animals occupy different positions in the marine food chain and are therefore exposed to different levels of risk in relation to organochlorine biomagnification. BPMO activity in the striped dolphin was four times higher than in fin whale, the two species having dramatically different levels of DDTs and PCBs in their blubber. This difference, and consequently BPMO induction, was related to their different positions in the marine food chain, the dolphins having a fish diet and the whales feeding on macroplankton.
Genetics of Mediterranean cetaceans
The depletion of species and the loss of biodiversity world-wide have spawned a wide interest in identifying threats to endangered species, as for cetaceans. With the improvement of DNA molecular biology techniques, principles and methods of population genetics have been adopted as a tool for the conservation of biodiversity. Conservation genetics is an applied science with the important goal of describing into detail the composite genomes of endangered populations. In addition to ecological and demographic threats, it has become clear that populations that survive demographic contractions may undergo close inbreeding, genetic drift, and loss of overall genomic variation. These genetic factors increase the susceptibility of populations to environmental stochasticity, and eventually they can contribute to geographic extinction. When combined with toxicological, ecological and ethological data, genetic data give a valuable perspective of the status of the studied population, and can provide useful baseline information for the development of conservation management plans.
Since the beginning of its activity, the Tethys Research Institute has supported the genetic and toxicological approach to the conservation of cetacean species in the Mediterranean Sea. The ongoing activities, aimed at the collection of cetaceans samples for toxicological and genetic analyses, have been evolved with the following criteria: 1) the establishment of collaborations with organisations performing molecular and toxicological analyses on cetacean species (Department of Environmental Biology, University of Siena; Department of Biology, University of Brussels; Institute for Population Biology, University of Copenhagen; Department of Biology, University of Durham); 2) the promotion of specific programmes for the collection of samples from stranded and free ranging animals; 3) the development of new, non-destructive techniques for the remote collection of biopsy samples from free ranging animals, specific for each cetacean species, based on the results of behavioural studies aimed at assessing the reactions of the animals.
In spite of remarkable difficulties in biopsy sample collection, the Tethys Research Institute has gathered over the years a considerable number of samples from seven cetacean species: fin whales (N=172), striped dolphins (N=69), common dolphins (N=19), bottlenose dolphins (N=9), spotted dolphins (N=6), Risso's dolphin (N=1), and sperm whale (N=3). Genetic analyses of these valuable samples, currently underway, are going to shed light on many aspects of cetacean ecology and population biology.
Survey of bottlenose dolphins in north-eastern Sardinia
A series of boat surveys were conducted in June to evaluate the feasibility of a long-term population study of bottlenose dolphins in the waters adjacent to the island of Tavolara. Data from this preliminary study indicated a relatively high density of dolphins near the coast and in neritic waters (on average one sighting occurred every two hours of search). The animosity of fishermen against the dolphins and their hostile attitude (including shooting) towards them might explain the difficulties encountered in the attempts to observe and approach the animals.
Acoustic study of sperm whales in the southern Tyrrhenian and western Ionian Seas
A study to test dedicated equipment for acoustic detection and recordings of sperm whales (Physeter catodon) and other odontocetes was conducted in summer 1991. An hydrophone towed array was used to record continuously whale sounds during their tracking, and a computer software was used to assess approximate bearing of the sound source. Two individuals of sperm whales were tracked acoustically for 4 and 6 h respectively, thus enabling to record long session of acoustic behaviour. Moreover, the only one very distinctive coda ever recorded in the Mediterranean was obtained during these sessions.
Distribution and frequency of cetaceans in the Eastern Ionian Sea, Greece
A series of research cruises were organised, during summer, in the Eastern Ionian Sea, where very little information existed concerning the distribution and abundance of cetaceans. The study showed a remarkably predictable presence of common dolphins in the coastal waters of Ionian Greece, in apparent sympatry with bottlenose dolphins. By contrast, fin whales, striped dolphins and Cuvier's beaked whales (Ziphius cavirostris) - the other cetacean species encountered in the area - were sighted in the pelagic waters offshore the main Ionian islands.
Line-transect survey in the Corso-Ligurian Basin, with Greenpeace and the University of Barcelona
The survey, conducted in summer 1992 with the collaboration of the University of Barcelona and the Greenpeace Mediterranean Project, covered an area of approximately 60,000 km2, comprising the seas between western Corsica and the continental coast of France and Italy. Cetacean densities and abundances were calculated using line transect sampling methods. Fin whale and striped dolphin estimates obtained in the study area were, respectively, of approximately 1,000 and 25,500. The study confirmed the importance of the cetacean faunal assemblages in the Corso-Ligurian Basin, stressing the need for the adoption of conservation measures, such as the institution of an International Sanctuary for cetaceans. This also represented the first attempt ever to estimate cetacean population sizes in large portions of the Mediterranean Sea.
Yucatan Project: Sea turtles and dolphins
All sea turtles - except the Australian flatback turtle - are listed in the IUCN Red List as Endangered or Vulnerable. In the Yucatan Peninsula, in spite of laws (Mexico has had laws protecting the hawksbill sea turtle - Eretmochelys imbricata - since 1980), the impact of human activity on these endangered reptiles is considerable and difficult to control, especially in remote reserves as Rio Lagartos. A management and active conservation program to protect turtles in these areas is important at a local level and helps to stimulate public awareness in the region as regards these animals that are expected to continue their decline to extinction. Only a few sites of aggregated nesting by hawksbills remain in the hemisphere, and these reserves are important areas to protect both today and in the near future. The Yucatan Project's main purpose is to carry out a long-term investigation for sea turtle conservation in a reserve considered to be among the last surviving tropical paradises where the impact of human activities on these endangered reptiles remains difficult to control and evaluate. The Yucatan Project is also involved in a bottlenose dolphin study at the reserve to help contribute toward the conservation and the gathering of knowledge on another species. The dolphin research provides data on sighting frequency, group size, composition, and behaviour within this previously unstudied area.
In the past five years from 1992 to 1997, the Yucatan Project has also carried out various studies in collaboration with Biocenosis (Merida, Yucatan), collecting additional data that will help toward the establishment of a conservation strategy for the reserves. This data collection, conducted in El Palmar and Rio Lagartos Reserves, included: coconut tree reforestation, census of butterflies, birds and dunal flora, and hydrological studies in the "petenes".
Cetacean ecology in the Caribbean Sea
A series of research cruises to describe cetacean distribution and relative abundance was organised from December 1993 to March 1994 in the coastal waters of Venezuela, the Lesser Antilles and Puerto Rico aboard Tethys' research vessel Gemini Lab. Methods included visual sighting surveys and acoustic monitoring with a towed hydrophone array.
Survey in the waters surrounding the island of Asinara (NW Sardinia)
Regular surveys were conducted from sailing vessels in inshore and offshore waters of NW Sardinia, in order to investigate cetacean distribution and sighting frequency. Five cetacean species were observed in the area: fin whales (Balaenoptera physalus), striped dolphins (Stenella coeruleoalba), bottlenose dolphins (Tursiops truncatus), common dolphins (Delphinus delphis), and Risso's dolphins (Grampus griseus), totalling 122 sightings. Photo-identification techniques and behavioural observations enabled to gain insight into cetacean social ecology, habitat use and site fidelity.
Poseidon project: Interaction between man and marine fauna in the Corso-Ligurian Basin Sanctuary
The Poseidon project was conducted in collaboration with Dr. Pierre Beaubrun, University of Montpellier, with the aim of monitoring the human and marine fauna interactions within the International Sanctuary in the Corso-Ligurian Basin.
During Tethys research cruises, information and geographic position of marine fauna (cetaceans, birds, fishes, invertebrates etc.), human activities (ships, ferries, petrol-ships, fishing activities, touristic boats, military navy, etc.), together with environmental variables were recorded at regular intervals, within pre-designed sub-areas. A first catalogue where the above mentioned variables were mapped was prepared in 1995 and an updated version is in preparation. The catalogue aims at describing the Sanctuary area in terms of human impact and presence of marine fauna, thus being an useful tool for conservation purposes.
Acoustic survey to assess odontocete distribution in the Ligurian Sea
Systematic acoustic monitoring can be used to obtain an index of abundance of vocalising animals. An acoustic survey to test this hypothesis was conducted in collaboration with the International Fund for Animal Welfare, in the waters of the Ligurian Sea Sanctuary. Recording sessions were performed at regular intervals at day and at night, either during navigation or drifting. Levels of odontocete clicks and whistles were scored, as well as levels of background water noise, shipping noise and self noise. Results showed that acoustic survey is significantly more efficient than visual survey in determining odontocetes distribution and habitat partition. Also, the method showed to be an useful tool to assess striped dolphins behaviour, which is by far the most frequent dolphin species in the Ligurian Sea. The study indicated that the acoustic approach may provide highly relevant information to the conservation of cetaceans in the Mediterranean Sea.
Distribution and sighting frequency of cetaceans in the Canary Islands
Research cruises in the Canary Islands were conducted during a three-year winter-study in the waters off, respectively, Lanzarote (1995), Tenerife (1996) and Gomera (1997). Little information, mostly based on stranding reports, was available on cetacean distribution in the Canaries. Observations at sea were targeted on the ecology of particular species, such as the pilot whale in Tenerife waters. The study provided a comprehensive view about relative cetacean distribution and abundance in the highly productive waters of the Canary Islands. Pelagic cetaceans included spotted dolphins and common dolphins; these two species seem to alternate seasonally within the area. Occasionally, beaked whales were also encountered along the continental slope. Pilot whale sightings confirmed the regular presence of this species off Tenerife and within the less touristic waters off Gomera. An attempt to monitor behavioural differences between pilot whales that occur off Tenerife and are accustomed to intensive whale-watching activities, and Gomeran pilot whales was undertaken. Preliminary results showed evidence of different behavioural responses between the two communities, thus indicating a significant anthropogenic impact on the whales off Tenerife.
Cetacean survey in the waters off Southern Morocco
During the winter 1996 a field expedition to the coastal waters of Southern Morocco was organised. Targets included: 1) to verify if right whales (Eubalaena glacialis) could still be found in that area, a former wintering ground for this species, 2) to evaluate environmental conditions of the region and assess its suitability as a right whale habitat, 3) to investigate the status of other cetaceans living in the area and 4) to establish a cetacean sighting and stranding network in co-operation with local authorities. The survey yielded no cetacean sightings except inside Dakhla Bay, were communities of bottlenose dolphins (Tursiops truncatus) and Atlantic humpbacked dolphins (Sousa teuszii) were found to co-exist.
Local knowledge of a regular, predictable presence of large whales in the coastal zone was lacking. On such grounds the hypothesis that the area still serves as a winter concentration site for the remnants of an eastern North Atlantic right whale population, although not falsified by this study, seems rather unlikely.
Finally, with the objective of increasing baseline information on the local cetacean fauna, and particularly concerning the possibility that right whales may be sighted in the future, a procedure was established for the long-term routine reporting of cetacean sightings and strandings by the Royal Navy of Morocco to the Groupe d'Etudes des Cþtacþs et Pinnipúdes du Maroc, Rabat.
Short-term tracking of whales
A new method for short-term tracking of free ranging whales has been combined with the recording of respiratory events. The methods enables the study of animal behaviours under different natural conditions and in response to human disturbance and permits to shed light on physiological principles and controls underlying locomotory functions. The tracking system is based on simultaneous determination of vessel position with a GPS device, together with relative distance and azimuth of sighted animals by means of a laser range finder or, alternatively, a RADAR apparatus, while respiratory data are collected and stored with an event recorder, for further processing.
A dedicated software (©HighWhale), specifically developed on a portable PC-Windows, simultaneously receives a GPS signal for on-line determination of boat position and whale relative position data from Leica Vector DAES 1500 binoculars, while respiratory data are subsequently loaded. The output is an integrated framework of locomotory (actual track, distance travelled, velocity relative to water surface, index of linearity) and respiratory information (dive and surfacing duration, interval between blows, blow rate). The combined technique has been extensively employed in the Ligurian Sea to investigate Mediterranean fin whale locomotory and respiratory pattern under physiological conditions and in response to purposeful disturbance. In the summer feeding ground the tracks appeared distributed in a bimodal fashion due to two distinct swimming patterns (on the basis of an index of linearity) and could be referred to a sub-linear travel pattern through the area and a convoluted feeding pattern within a relatively restricted area. The differences concomitantly found in respiratory pattern would also substantiate a more elevated energetic requirement inherent in the alimentary behaviour. Purposeful disturbance, as short distance observation with inflatable boat or biopsy sampling manoeuvres, substantially induced an escape response entailing detectable change in animal behaviour and prolongation of dive periods. A general trend in breathing control consists in a modulation of the ratio between time spent near the surface and that spent in prolonged dive.
Underwater passive acoustic tracking of whales
Blue-, fin- and sperm whales were tracked acoustically while monitoring distribution and acoustic behaviour of other cetaceans within the same area in the Ligurian Sea, Mediterranean Sea, Monterey Bay (California, USA), and the Bay of La Paz, Baja California, Mexico. A towed dipole hydrophone array and semisubmersible free-drifting spar buoys (each equipped with a GPS data logger, DAT recorder, and a VHF radio for time synchronisation) were deployed in the presence of whales. Whales were recorded and recordings processed on multichannel-files. The whales could be discriminated and located in space by computing arrival time differences of sounds at the sensors and calculating bearings of the sources during post-processing. A hyperbolic least-squares fixing algorithm is used to calculate locations of vocalising marine mammals. Two-dimensional locations were obtained for several samples and three-dimensional locations were obtained when the depths of several hydrophones were known.
Advantages of this combination were: 1) the freedom of the towing vessel to pursue other objectives after buoy deployment (an individual female sperm whale was tracked to obtain a fluke-based individual identification); 2) the active variation of the array aperture to provide virtually infinite spacing combinations required for locating different cetacean species; 3) the use of the spar buoys to eliminate the right/left ambiguity of towed arrays while maintaining real-time tracking abilities; 4) the enhanced recording quality of buoys unaffected by towing noise and 5) the extension of detection ranges by the cross-correlation of sounds from different sensors to extract masked signals. The result is a system that permits the simultaneous tracking of focal animals while conducting acoustic surveys of cetaceans over large geographic areas.
Continental Slope Odontocete Project
Telemetry and diving behaviour of fin whales in the Ligurian Sea
In order to monitor diving behaviour of fin whales while in their feeding grounds in the Ligurian Sea, during summer 1998 few individuals have been tagged with velocity-time-depth-recorder (V-TDR), remotely implanted by means of a suction cup. The tags were equipped with VHF radios to follow the whales when surfacing and to collect the tags after spontaneous detachment from the animal. The instruments collected fundamental data regarding the depth and the velocity of the whale as well as temperature and light level of the water. These data provide information on the diving capabilities of this species and preliminary evidence of deep diving performances unknown until now. These data therefore support the hypothesis that these marine mammals might opportunistically reach deeper depths than those since now recorded, in order to catch the preys they feed on.
Behaviour of a solitary, "sociable" common bottlenose dolphin in southern Italy
The behaviour of a solitary male common bottlenose dolphin nicknamed "Filippo" was observed between 1999-2000 near Manfredonia, Italy (southern Adriatic Sea). The dolphin - first reported in the area around 1996 — became increasingly "sociable" towards humans, and by November 1997 he started to interact regularly with our species. From spring 1998 Filippo settled in the harbour of Manfredonia, where he could be predictably sighted since, within a 10-km coastline range. Observations were opportunistically conducted from the wharf or from small boats, based on a 3-min behavioural sampling routine. Over 100 h of observation were conducted while Filippo was in the port, where he seemed to spend most of his time. Observations also focused on the behaviour in open waters, in the harbour’s proximity, where the dolphin usually moved following boats or to interact with swimmers or scuba-divers. Five behavioural states were defined: Resting, Milling, Feeding, Interacting/Feeding and Interacting. Resting - the most frequent behaviour overall - accounted for about 80% of the time spent in the port, and was never observed out of the port. Interacting with boats and humans was the second most frequent behaviour, accounting for 16% and 67% of the time spent in and out of the port, respectively. Feeding and Interacting/Feeding totalled 27% of the time spent out of the port, and about 1% in the port. The behaviour in and out of the port differed significantly for all activities except Milling. The remarkable proportion of time spent either resting or interacting with humans and boats, as compared to foraging, may reflect ease of finding prey in the area.
Scientific consultancy for a study on common bottlenose dolphin interactions with fisheries in the Asinara Island State Marine Reserve, Sardinia, Italy
The Tethys Research Institute has acted as scientific consultant in charge of behavioural data collection and analysis for a project on cetacean-fisheries interactions in the Asinara Island State Marine Reserve (Sardinia, Italy). The study is being conducted by ICRAM, Italy. Behavioural data collected over three years of observations were consistent with the hypothesis that common bottlenose dolphins interact with local fisheries targeting red mullet (Mullus barbatus), while in the presence of other kinds of fishing gear the dolphin behaviour does not differ significantly from the behaviour shown where no fishing gear is present. The results of this study contribute to providing local managers with the necessary scientific information to regulate fishing and prevent negative dolphin-fisheries interactions.
A partnership has been established between the Tethys Research Institute and Delphis MDC, a research and conservation group that is studying cetaceans around the islands of Ischia and Ventotene, Italy. Results from ongoing collaborative studies indicate that local dolphins are exposed to threats including overfishing, illegal driftnetting and disturbance resulting from heavy boat traffic.