Sperm whales are excellent swimmers and spend most of their time (~23 hours a day) diving to depths of 600-1000 m in search of food, deep-living squid. Each dive may last for 45-60 minutes and during this period the animals are exposed to extreme conditions: Pressures up to 100 atmospheres and absolute darkness. At the same time they have to keep their breath and use the air trapped in their nasal cavities to produce so-called regular clicks, repeated broadband biosonar signals that allow them to detect and locate their pray. At the end of the dive the exhausted animals ascend to the surface where they stay for 10-15 minutes to get some rest, renew their air and prepare for the next dive. If during this time a large ship crosses the area a collision is imminent.

SaveWhales is a project funded by OceanCare for the development of a real-time sperm whale observatory close to a heavy shipping lane off the south-western coast of Crete. The observatory consists of three autonomous moored stations at distances of about 1000 m. from each other forming an isosceles triangle , each equipped with a hydrophone at a sufficient depth to pick up the click sounds produced by the animals during their dives. The acoustic recordings are preprocessed in-situ for click detection and transmitted by GPRS to the analysis center located at the Institute of Applied and Computational Mathematics at FORTH (FORTH-IACM). There, all three data streams are combined to estimate the location of the animals and the localization results are forwarded in near real time to MarineTraffic -a ship tracking intelligence site- for alerting nearby vessels in an attempt to mitigate ship-whale collisions. Results are also forwarded to Pelagos Cetacean Research Institute and CINTAL (the other partners of the consortium) for verification and further studies.

The Hellenic Trench, formed by the convergence of the Eurasian and the African plates in the Ionian and Libyan Sea is a high risk area for ship strikes, especially in the area southwest of Peloponnese and southwest of the island of Crete. These are areas of steep bathymetry, favorable for sperm whales, and heavy ship traffic. Since 1998 members of the Pelagos Institute have observed and photo-identified about 200 sperm whales in the Hellenic Trench, which is an estimate of the entire Eastern Mediterranean population, and some 20 deceased and stranded animals with clear ship strike marks and cuts in their body. This is a large percentage taking into account the small population size.