Concerns, hope and optimism for the deep divers of the Hellenic Trench

Alexandros Frantzis writes from on board vessel Song of the Whale, from the Hellenic Trench, off south Crete, Greece about his concerns, hopes and optimism for the deep diving whales of the Hellenic Trench during IFAW-supported survey work:

We are surveying pelagic waters of the Hellenic Trench, in the framework of a huge international effort made by hundreds of scientists and people dedicated to the conservation of cetaceans. All who are involved - coming from many different nations and various fields of expertise - have joined forces with the goal of setting a baseline of abundance for all cetacean species in the Mediterranean and Black Sea.

This is the ACCOBAMS Survey Initiative; an idea that was put on the table some 20 years ago after the birth of the Agreement on the Conservation of Cetaceans in the Black Sea, Mediterranean Sea and Continguous Atlantic Area (ACCOBAMS), and which is now close to completion in the immense task of surveying the entire Mediterranean Sea by both air and sea.

accobams mediterranean study of dolphins and whales

While sailing south of Crete, we passed close to Gavdos Island at the southern edge of Europe. We were happy to see several bottlenose dolphins, and for good reason. A bottlenose dolphin sighting - while perhaps not terribly exciting in the life of a cetologist - confirms that this "extreme" population unit is still present in its natural habitat. We first recorded the presence of these dolphins in 1998 and had only a few sightings until 2000. 

Our survey here is targeting a group of species known as “deep-divers”: the sperm whales and the Cuvier’s beaked whales that are the world champions in diving into the abyss at 2,000 or even 3,000 metres, in search of their prey, the meso- and bathypelagic squids. The Hellenic Trench is the core area of their habitat in the Eastern Mediterranean basin, and since 2017 has been designated an Important Marine Mammal Area (IMMA). Since its early years, ACCOBAMS has proposed that the Hellenic Trench become a Marine Protected Area (MPA) for cetaceans. Just last year, just two small sections became part of the NATURA 2000 Network, but this doesn’t seem to be enough if we want these amazing animals to go on living on our doorstep. 

Threats to the species

  • Ocean noise: At least five military exercises using sonar have taken place along the Hellenic Trench since 1996 resulting in the death of at least 45 Cuvier’s beaked whales. Seismic surveys also started here over the last decade, creating a noise nightmare for cetaceans that already suffer from ship noise and other heavy marine traffic.
  • Plastic pollution:  Floating rubbish and plastic is often swallowed by deep-diving whale species along the Hellenic Trench, mistakenly taken as squid as they sink to great depths. About 60 percent of the stomach contents of sperm whales, beaked whales and Risso’s dolphins analysed in Greece were found to contain large plastic items. One young sperm whale died because of plastic ingestion, having more than 100 plastic items in its stomach (drink cans, construction materials, plastic bags, plastic fishing nets, etc).
  • Ship strikes: The most significant threat by far for these sperm whales is ship strikes. Throughout this survey, we have observed cargo ships, ferries, tankers and other large vessels moving fast along the 1,000m contour of the Hellenic Trench, which coincides with the peak of sperm whale density in the area. At least one sperm whale strands each year in Greece, found with obvious propeller scars on its body. Many more are likely hit, but their carcasses never reach the coast. With the total number of sperm whales in the Hellenic Trench at less than 250, this volume of loss is likely unsustainable. 

The situation is dire, but it also gives us hope. Could the Hellenic Trench become a positive conservation paradigm? Since we identified and have studied the problem, it is now clear that there is a solution, and it's perhaps much easier than what we might have thought.

IFAW recognizes the importance of this conservation issue and is providing funding to both the survey and our efforts to scientifically document a solution to the problem. Our work may help support Greek authorities in their efforts to move quickly before it’s too late for these sperm whales.

Recent findings by IFAW and PELAGOS Cetacean Research Institute have shown that the threat of ship strike would be dramatically reduced if the ship traffic is sent some 10km further offshore along the Hellenic Trench. The potential delay these large vessels may face would average merely ten minutes on trips lasting two or more days.

accobams Mediterranean study of ship strike on whales and dolphins

What is needed now is for Greek decision-makers at the Ministry of Mercantile Marine and Island Policy to officially submit their proposal to the International Maritime Organization (IMO) next February. After two decades of efforts for the sperm whales of the Hellenic Trench, we are finally close to creating a positive example of conservation success. 

Thank you to the many dedicated people out there, with the good will, knowledge, scientific tools and above all the desire to preserve this irreplaceable environment. This is our chance to save and protect the Mediterranean's whales and dolphins, for a brighter future for all of us!

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Brian Sharp, Emergency Relief Officer, Stranding Coordinator
Manager, Marine Mammal Rescue and Research
Dr. Maria (Masha) N. Vorontsova, Senior Advisor to the IFAW Marine Conservation
Senior Advisor to the IFAW Marine Conservation Program
Matt Collis, Director, International Policy
Director, International Policy
Patrick Ramage, Program Director, Whales
Program Director, Marine Conservation