Interview with Giuseppe Notarbartolo di Sciara
Mr. Notarbartolo, beaked whales are mysterious animals. They dive deep, almost don’t show themselves and have bodies full of marks. Could you describe these animals a bit more? Where do they live? How is their nature and character? What are their behaviours?
Beaked whales are a fascinating group of Cetaceans, belonging to the family Ziphiidae, which comprises 5 genera and 22 species. Of all these, however, only one, the Cuvier’s beaked whale Ziphius cavirostris, occurs regularly in the Mediterranean Sea. All species are deep divers, spending a large portion of their life underwater to hunt deepwater squid which are their preferred prey, and are therefore greatly adapted to a lifestyle which is extremely challenging for an air-breathing mammal. Such lifestyle, in addition to their shyness and levels of sociality that are lower than that of their delphinid cousins, makes them very difficult to observe and for this reason they have remained rather mysterious and amongst the least known cetaceans. Some species have been described solely on the basis of the finding of dead animals, found stranded on a beach.
How can beaked whales dive almost 2 kilometres deep without taking a breath for up to one hour?
Because of their extraordinary physiological and behavioural adaptations. Their muscle and blood contain very efficient oxygen-fixing proteins, so that they can bring down the minimum possible amount of air in their lungs, which could be a source of decompression problems. Nevertheless, electronic tags which were fitted on some of these animals with suction cups have revealed that when they swim back to the surface after a long dive they have a very complex pattern of vertical swimming which is likely to have a vital function in helping the animals’ body to get rid of dissolved gasses in their circulatory system in order to avoid decompression problems.
Where in the Mediterranean do I have the best chance to see a beaked whale?
Cuvier’s beaked whales are widely diffused in the Mediterranean, wherever waters are deeper than approximately 600 m, however they also have their preferred locations where finding them is more likely: these include the Alborán Sea, the Ligurian Sea, the waters east of Corsica, the Ionian Sea on both sides (Italy and Greece), and the waters to the southwest of Crete.
Beaked whales do extremely suffer from the increasing underwater noise. Why?
All Cetaceans are very sensitive to noise because they use it to navigate in the dark and to communicate. However, beaked whales are obviously particularly sensitive given that upon being hit by particular types of noise, such as some kinds of naval sonar impulses, these animals are known to strand and die.
Why is underwater noise for beaked whales deadly? Do these animals die already in the water or after they stranded on the land?
We are still unsure about the causes. I, like many other colleagues, suspect that the cause is primarily behavioural, i.e., the animal for some reason gets scared during its ascent during a deep dive, and rushes to the surface without performing correctly whatever it normally does to avoid decompression problems. Once this behaviour leads to the severe problems that we have often observed (called the “gas and fat embolic syndrome”), the sick animal strands (perhaps to be able to stay at the surface to breath in spite of its weakness). However, I would be surprised if the whales that strand weren’t just the tip of the iceberg of those in their population that get affected by anthropogenic noise.
Is the underwater noise in the Mediterranean a threat/danger for individuals only? Or for whole beaked whale populations?
If the introduction at sea of noxious anthropogenic noise, such as naval sonar and seismic surveys, were only occasionally performed and sufficiently far from beaked whale critical habitat, I think problems would be limited and perhaps inconsequential. If, on the other hand, noise-making agencies want to have a free-hand on where and how often to operate, I think this would be incompatible with the legal requirement of protecting Mediterranean beaked whales.
If nothing changes and underwater noise in the Mediterranean keeps increasing, what do you think: how would the situation for beaked whales in 50 years be?
Whales would be increasingly chased from their habitat, which could likely reduce the population size to a point of no return. However noise is not only harming beaked whales. For instance, fin whales – the admiral of the Mediterranean cetacean fleet – have been shown to leave areas where seismic surveys were run. Evidence is mounting that seismic surveys have an effect on other components of marine biodiversity, such as squid. So the problem of anthropogenic noise is to make it compatible not only with beaked whales’ survival, but with the maintenance of the Mediterranean good environmental status in general, which is prescribed by European and international law.
Which part do NGOs such as OceanCare play in the fight against the underwater noise? Where do you see opportunities for OceanCare to bring more silence to the Mediterranean?
Until now NGOs such as Ocean Care have played an essential watchdog role because in their absence it is quite obvious that the countries would not have done anything effective to concretely address the issue. In fact, the countries still haven’t done anything, so it is necessary that effort be continued by the representatives of civil society so that the laws are respected and the Mediterranean Sea and its fauna be conserved.