Today during the morning, we received several reports about the observation of a group of large whales in the Adriatic Sea. Through the analysis of observation footage near Korčula sent to us by citizens, we have determined that it is not a fin whale (Balaenoptera physalus) but rather a group of at least five sperm whales (Physeter macrocephalus). Considering that these animals usually inhabit depths exceeding 1,000 meters, they are at risk of stranding and distress in the Adriatic!

Given that sperm whales inhabit deep-sea areas and their population is not large, sightings of sperm whales in the Adriatic are not common. Rare but regular presence of sperm whales in the Adriatic is recorded only through our sound recording devices in the deep southern part of the Adriatic Sea and near the Otranto Strait.

Unfortunately, in most cases, encounters with sperm whales in the central and northern Adriatic have resulted in stranding and death of individuals from the observed groups, mostly on the Italian side of the Adriatic Sea. Therefore, it is essential to monitor this group’s movements in order to determine their trajectory and take timely rescue actions if needed.

Thanks to the monitoring of their movements in Croatia and based on citizen reports and media coverage, in September 2014, we managed to alert colleagues in Italy about the possibility of the group appearing in Italian waters. The result was a timely response from the Emergency Response Group in Italy, and four out of seven individuals were successfully returned to the sea. This was the first successful effort to return sperm whales to the sea conducted in the entire Mediterranean!

The most recent sperm whale sighting in the Adriatic was near Rovinj in August 2016 when three adult individuals were present in the area for several days. With the help of citizens’ photographs, one of the three observed animals was identified by colleagues involved in their research in catalogs in Greece and Italy, confirming that these animals utilize the entire Mediterranean Sea as their home.

As our goal is to ensure the safe departure of this group of sperm whales from the Adriatic, we urge all citizens to promptly report their observations so that we can track their movements and take necessary actions as required. Reporting when you are in proximity to sperm whales or immediately after observation will greatly aid us in locating them, as our research teams on Vis and Lošinj are in the field and can head to the observation locations.

In case of observation, please take photographs and/or video footage of the animals and note the exact location, direction of movement, and time of observation. Report information about sperm whales (preferably as soon as you observe them!) to us at the phone numbers of the Blue World Institute: 051 604666 or 091 4637424, email, or via the Marine Ranger mobile application, which can be downloaded from

Despite their size, sperm whales are harmless to humans if not approached closely. Given that the animals are likely exhausted, disoriented, and distressed due to being in an unfamiliar environment, we kindly ask that you do not approach or harass them, to avoid inadvertently causing their stranding and demise through your actions!

Further information about sperm whales will be posted on our website ( and our Facebook page ( Thank you for your help and cooperation!

For more detailed information, please contact us directly or visit our website.


Kaštel 24, 51551 Veli Lošinj,

t: +38551604666

Sperm Whales

Sperm whales are the largest species in the toothed whale group (Odontoceti), which also includes dolphins. Each side of their narrow lower jaw contains up to 26 conical teeth. They inhabit all the seas and oceans of the world except for polar regions and prefer continental slope areas. They mainly feed on large cephalopods, which they hunt at depths exceeding 1,000 meters. Their coloration is gray-black or brown, and they can have white markings on their belly and around their mouth. Adult males can reach up to 20 meters in length and weigh over 60 tons, while females are smaller. They can live for over 60 years and reach sexual maturity at 8-12 years old. Sperm whales live in social groups of 5-15 individuals, consisting of females and calves, while males often live alone. Unlike their oceanic counterparts, male sperm whales are frequently seen in groups in the Mediterranean, indicating a different social structure.

The population of sperm whales in the Mediterranean is genetically distinct from the nearest population in the Atlantic, indicating isolation. Sperm whales in the Mediterranean are directly threatened by entanglement in (illegal) fishing nets and ship collisions. The mortality caused by nets and ships today is unsustainable, leading to a continued decline in their numbers. Strong underwater sources of noise, such as seismic surveys and low-frequency sonar used by the military, also pose a threat, causing mortality and injury. Furthermore, disturbance from heavy maritime traffic and plastic pollution, which the animals ingest mistaking it for prey, further negatively impacts them.

Their habitats in the Mediterranean are associated with great depths and locations where the seabed drops steeply (continental slopes, submarine canyons). The area of highest abundance near the Adriatic is in the Hellenic Trench, a sea depression over 4,000 meters deep between the Ionian Sea and Crete, separating the African and Hellenic plates. Sperm whales in the Mediterranean undertake extensive migrations within the entire basin, confirmed through photo-identification.

The population residing in the Mediterranean is estimated to be fewer than 2,500 individuals, and their status is listed as “endangered” in the Mediterranean according to the International Union for Conservation of Nature (IUCN) Red List criteria. The majority of individuals in the Mediterranean are found in the western part, while the estimated population in the eastern Mediterranean (including the Adriatic) is only 300-400 individuals! Hence, this event demands additional attention. Sperm whales are strictly protected in Croatia.