A team of international researchers, led by University of Haifa’s Dr. Aviad Scheinin, has documented the longest journey of a sperm whale to date.
In a study published in Aquatic Conservation: Marine and Freshwater Ecosystems, the researchers used photo-identification and comparison with catalogs across the region to provide evidence of at least one immature male whale using the wider Mediterranean Sea with a distance between sightings of 2,800 kilometers (1,740 miles).
To their knowledge, this is the first documented example of a long-range eastward movement of an immature male sperm whale from the Ligurian Sea to the easternmost area of the Levantine Basin.
Dr. Scheinin—an Apex Predators Principal Investigator at University of Haifa’s Morris Kahn Marine Research Station—worked alongside Kirsten F. Thompson of the University of Exeter and Greenpeace Research Laboratories and Jonathan Gordon of the University of St. Andrews in the study, whose objective was to use passive acoustic monitoring and a non-systematic visual survey to generate data on the presence and ecology of cetaceans within Israel’s exclusive economic zone (EEZ).
In the study, two passive acoustic surveys were carried out during April and May 2022 onboard the Greenpeace SY Witness, a 22.5-meter (74-foot) sailing vessel, using both a sail and a motor at a mean speed of six knots across both surveys. About eight sperm whales were acoustically detected.
One whale was photographed and deemed an immature male based on its size and characteristic head shape. A subsequent comparison with eight Mediterranean photo-identification catalogs confirmed that this whale has been seen on 12 earlier occasions, with the longest distance between sightings being 1,740 miles, which is the longest documented movement of an individual sperm whale in the Mediterranean.
The researchers believe that a sperm whale would likely have a specific incentive to travel such a long distance between narrow and relatively shallow habitats, such as the Sicily Channel or the Strait of Messina, and that this travel pattern could reveal opportunities to use targeted new feeding grounds.
For example, real-time passive acoustic tracking of individual whales could help to prevent collisions, and inter-basin-traveling sperm whales produce foraging clicks when passing in these pinch points, a method that could be critical for reducing death rates in these areas.
“The gap of knowledge of marine life in offshore waters in the Mediterranean is tremendous,” Scheinin said. “Spotting these sperm whales is important to our knowledge about biodiversity, because if a whale is willing to travel such great distances at considerable risk, then it means it must have found a diverse and lush source of food. Being apex predators of the deep sea makes them important bioindicators.”
The Mediterranean Sea is one of the most highly impacted enclosed seas on Earth, as it is bounded by heavily populated coastlines and very fast-warming temperatures. Local marine mammal populations are subject to an array of threats that include anthropogenic noise and other pollution, as well as poor management of fisheries. These conditions position the Mediterranean as an early-warning model system that sheds light on the future trajectory of climate change in oceans worldwide.
In many regions, particularly the eastern Mediterranean, sperm whales’ population numbers, distribution and the threats they face remain poorly understood. Now, the team’s findings have prompted Israel’s Ministry of Energy to request that Scheinin conduct additional offshore marine mammals research into Israel’s EEZ.
“Hopefully, this is a starting point of long-term research on the EEZ,” Scheinin said. “I hope we will better understand offshore marine mammals in our backyard and explore biodiversity in our Mediterranean Sea. This is a dream I have been waiting to fulfill for 20 years!”
