To denounce the dangers of deep seabed mining, Greenpeace is renewing its approach by focusing on a strong argument: the blue whale (Balaenoptera musculus), the largest animal in the world, considered endangered. The NGO publishes Tuesday, February 14 a study on the impact for various species of cetaceans, of the extraction of minerals in the deep sea. Featured in the magazine Frontiers in marine science, this work comes from the research laboratory of Greenpeace and the University of Exeter in the United Kingdom. It is reviewed in particular by researchers from the Australian Institute of Marine Sciences.
The team relies in particular on current knowledge of the Clarion-Clipperton zone, located between Mexico and Hawaii in the Pacific. This is the object of much industrial covetousness: to date, it is concerned by seventeen deep-water exploration permits. It is also in these parts that in the fall of 2022, The Metals Company carried out its campaign to harvest 3,000 tonnes of polymetallic nodules 4,000 meters below the surface, as a “test permit”.
In addition to the blue whale, at least twenty-five species of cetaceans are present in this region which extends over 11.65 million square kilometers and dives to an average depth of 5,500 meters. Evidenced by the ecological analyzes of populations of mega vertebrates of the Ocean Biodiversity Information System (OBIS) designed by Duke University in the United States. This database lists baleen whales in this part of the world: gray, humpback, Bryde’s whale, odontocetes called beaked whales (Cuvier, de Longman, de Blainville, pygmies) as well as various dolphins. Some species are very rare and listed as critically endangered by the International Union for Conservation of Nature, IUCN.
Reduction of habitats
If authorized by the International Seabed Authority – a United Nations agency – the exploitation of mineral resources in the high seas could receive a green light as early as this year 2023. This industry should mainly focus on the quest for nodules in the abyssal plains, but could also target ferromanganese crusts present on seamounts. It is above this kind of relief that cetaceans gather, take a break and socialize during their migrations.
Disturbances to the ocean floor will obviously reduce habitats for marine wildlife and affect the food chain as a whole. However, for cetaceans, it is the noise that the authors of the study put at the top of all the dangers. Because extractive activity requires the sending of remote-controlled vehicles from the bottom, a system that sucks up large quantities of sediment over the entire height of the water column, which then has to be returned to the ocean times the ores recovered by the surface ship. Constantly running motors and pumps generate sounds that travel up to several thousand kilometers from their source of emission. “Submersible pumps, mud flow and remotely operated vehicles distribute noise throughout the water column”explain the researchers.
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