A recurring problem in the Mediterranean, ship strikes between cetaceans and boats (fishing boats, ferries and cargo ships as well as racing boats and whale watching boats) are partly responsible for decreasing the size of the populations of large cetaceans that live, feed and breed in the area. These threats are also worse for populations that are small in number and/or isolated geographically.
Some species have been studied in greater detail than others, in part as a result of the collaboration established between researchers and shipping companies following the creation of the Pelagos Sanctuary. Thus we now know that for two species, while they rank among the largest on the planet, ship strikes are a threat: fin whales and sperm whales. Genetic studies have shown that these cetacean populations are isolated from those in the Atlantic and are thus more vulnerable. In addition, the fact that they are few in number and have a low birth rate means that the people who manage them must remain attentive with regard to the future of both species, which are already victims of other disturbances caused by humans. Lastly, these studies show that over 6% of the individuals at sea (identified from photographs) and more than 20% of stranded individuals show traces of ship strikes.
It has thus become imperative to map out where ship strikes are the most frequent, to design mechanisms and measures to reduce the risk of ship strikes in these areas, and to pursue scientific research to further the knowledge on these species and to adopt specific management measures.
In addition to this ecological consideration, ship strikes pose a safety problem for high-speed vessels. For ships, a ship strike with a whale at a speed of 30 or 40 knots can breach the hull and cause water to flow in. In recent years, this has occurred on a number of occasions along the routes linking the islands, to say nothing of sanitary threats, timetabling issues, costs of repair, and reputation risks that shipping companies face in the event of a ship strike event.
We should also note that the unregulated presence of whale watching boats around cetaceans can also lead to ship strikes with the animals. For example, thirty-two ship strike events with large cetaceans (sperm whales, killer whales and four mysticete species) were recorded around the world between 1984 and 2003 (IWC, 2005). Worse still, a ship strike event between a sperm whale and a high-speed ferry in the Canary Islands killed a passenger on board. The last two incidents however occur less frequently than collisions with ships.
Management options
The scientific community and certain shipping companies are alarmed by these accidents, particularly within the Pelagos Sanctuary. It is for this reason that researchers and marine transport groups made a commitment to develop a program designed to limit the risk of ship strikes. Since this research and these partnerships began exploring ship strikes due to marine traffic in the Mediterranean, there have been results and solutions have been proposed by the French Party of the Pelagos Sanctuary. These focused, among other ideas, on:
- organizing annual professional training (an annual professional training organized by Souffleurs d'Ecume association, is already implemented by the French Part of the Pelagos Sanctuary at the Ecole Nationale Supérieure Maritime (ENSM) in Marseilles;
- conducting scientific studies: applied research (scientific monitoring procedures) as a means of learning more about large cetaceans;
- drawing up maps showing areas in which there is a ship strike risk (click here to consult the most recent scientific study);
- developing technological tools for use by shipping companies, as in, among others, the REPCET system (Network for the Real-Time Reporting of the Locations of Large Cetaceans);
- having an observer on board passenger transport ships that travel through the Pelagos Sanctuary (the location of all sightings is recorded on observation forms);
- using alternative routes, and reducing cruising speed.
The REPCET system, launched by the Souffleurs d'Ecume association, was approved by the Pôle de Compétitivité Mer PACA (Marine Business Cluster for the PACA Region) in June 2007 and aims at helping to reduce the risk (initially) of daytime ship strikes between boats making regular journeys and large cetaceans. REPCET uses the density of boat traffic in the Mediterranean to improve the detection of large cetaceans by boats on regular routes by means of a computer network. Other technological tools are also under study (Active High Frequency Phased-Array Sonar, sonar, light-enhancing binoculars, infrared).
Scientific research within the Sanctuary must continue, then. In order to be able to respond to the problems posed by boats and ships, the comparative analysis of the distributions (and their variations) of cetaceans and marine activities within the Sanctuary zone must be carried out and, in the future, a partnership with the shipping companies should be created.