Where are the great marine animals of the Mediterranean, such as the fin whale, the sperm whale or the bottlenose dolphin? How does their distribution change over the course of a few weeks? All indications suggest that these species shift between marine areas in a remarkably short time and over relatively small spatial scales. Some species, such as the striped dolphin, maintain a relatively stable presence in certain areas, while others, such as the fin whale, move and concentrate in different areas between one observation campaign to the next.
These are some of the main conclusions of the Synoptic Ferry Observation Network (SYNFONY) project, an initiative for monitoring marine megafauna in the Mediterranean carried out with the support of ferry lines and shipping companies. As part of the project, the Barcelona–Tanger–Barcelona route is coordinated by professors Odei Garcia-Garin and Manel Gazo of the Faculty of Biology and the Biodiversity Research Institute (IRBio) at the University of Barcelona. More than 20 volunteers have also taken part in the project, mainly students from the UB’s degree programmes in Biology, Marine Sciences and Environmental Sciences.
A total of 707 sightings of marine megafauna
Between June and July, three scientific campaigns recorded 707 observations of marine megafauna, mainly of the eight species of cetaceans commonly present in the Mediterranean: the fin whale (Balaenoptera physalus), the sperm whale (Physeter macrocephalus), Cuvier’s beaked whale (Ziphius cavirostris), the common dolphin (Delphinus delphis), the bottlenose dolphin (Tursiops truncatus), the striped dolphin (Stenella coeruleoalba), Risso’s dolphin (Grampus griseus) and the long-finned pilot whale (Globicephala melas). Two species of sea turtle were also recorded: the loggerhead seaturtle (Caretta caretta) and the green seaturtle (Chelonia mydas).
Observations were carried out along 19 fixed shipping routes in the western Mediterranean and the Adriatic, which have provided a broad, simultaneous snapshot of the distribution of marine megafauna, particularly cetaceans and sea turtles. Thus, commercial ferries become genuine platforms for observing marine biodiversity: they use the routes they regularly sail to gather data on the presence and distribution of species.
A distribution that changes in a few weeks
One of the clearest examples is that of the striped dolphin: “During the first campaign it was observed more frequently and across a wider distribution area. In the third campaign, however, the sightings were much more spatially concentrated, especially on one of the routes in the Spanish corridor,” say experts Odei Garcia-Garin and Manel Gazo from the UB’s Department of Evolutionary Biology, Ecology and Environmental Sciences.
The fin whale showed a relatively stable number of sightings across the three campaigns. However, its distribution along the different routes underwent considerable changes.
“Sea turtles also showed significant variability. The loggerhead turtle was the most frequently observed taxon across the entire monitoring period. However, the number of observations decreased from the first campaign to the subsequent ones, while changes in its distribution within the network of monitored routes were detected,” the experts note.
SYNFONY is being developed as part of the Fixed Line Transect Mediterranean Monitoring Network (FLT Med Net), coordinated by the Italian Institute for Environmental Protection and Research (ISPRA), of which IRBio-UB has been a member for almost 10 years. This initiative draws on more than two decades of experience in collaboration with shipping companies.
Towards more dynamic risk management
Maritime traffic is one of the pressures that may overlap spatially and temporally with the presence of cetaceans and turtles. Data obtained by SYNFONY can contribute to developing new dynamic risk assessment models that integrate the presence of the species, the intensity of maritime traffic and environmental conditions within a single framework.
“The aim is to be able to identify more precisely which areas and which periods present a potential increased risk to marine megafauna and to advance towards a better understanding and management of the Mediterranean marine space,” the experts say.
“In this challenge, we must thank all the volunteers who, as observers on board, have made these campaigns possible, as well as the shipping companies and all the people and institutions who have contributed to the development of the project. Their participation and commitment is key in continuing to expand knowledge of Mediterranean marine biodiversity and advancing its conservation,” conclude Odei Garcia-Garin and Manel Gazo.