Greenland sharks are protected from fisheries | Polarjournal
Greenland sharks belong to the sleeper sharks or Somniosidae, a group of deep-sea dwelling sharks about which little is known. Studies have shown that Greenland sharks can live to be over 400 years old, which is a record for vertebrates. Image: Hemming1952 via Wikicommons CC BY-SA 4.0

On the one hand, the Arctic and sub-Arctic waters in the Atlantic are very rich in fish and therefore extremely lucrative in economic terms. But in the cold depths also exist many mysterious and unknown creatures that are important for research. One of them is the Greenland shark, the longest-lived vertebrate in the world to date. This species has now been placed under protection by one of the most important fisheries organizations.

The Northwest Atlantic Fisheries Organization (NAFO) adopted measures at its September meeting in Porto, Portugal, to prohibit the catch and retention in bycatch of Greenland sharks throughout the NAFO Area of Operation (Northwest Atlantic). An exception exists for retention as bycatch if a country explicitly prohibits the discard of fish bycatch. Marine conservation organizations welcome NAFO’s declaration of such protection for fish in the first place. As a result, the cartilaginous fish in waters from eastern Canada to the United States, Greenland, Iceland, the Faroe Islands and Norway are at least protected from specific fishing. They may still be retained as bycatch in Greenland, Iceland, Norway and the Faroe Islands, as these countries explicitly prohibit the discard of bycatch.

Greenland shark was traditionally hunted by some nations. Especially in Iceland, the fish is popular as “Hákarl”. It is estimated that thousands of sharks lose their lives each year and end up on drying racks. Images: Wikicommons CC BY-SA 4.0

The first push for Greenland shark conservation was made at NAFO in 2018. The Scientific Advisory Board recommended that members of the intergovernmental organization place Greenland sharks under protection. The recommendation was based on the fact that many of these deep-sea dwelling sharks are not only caught directly, but likely end up as bycatch in trawls targeting halibut and other economically relevant fish species. For an animal that, according to the latest findings, is the longest-lived vertebrate in the world at more than 400 years and is probably only able to reproduce for the first time at around 150 years of age, this means a great risk of rapidly reaching the brink of extinction. Each year, experts estimate that several thousand animals end up as bycatch, although reliable figures have been lacking. For economically the sharks play only a minor role, but are a delicacy in some Nordic countries. They are particularly well known in Iceland, where they are offered as Hákarl together with Icelandic Brennivin . However, the production is difficult and lengthy, as the meat must first be freed from all uric acid and fermented. In the end, the meat is dried before sale.

Very little is known about Greenland sharks, because the animals live at great depths and have probably never been common. Every now and then, however, they come to the surface for hunting. Actually native to the cold waters of the North Atlantic and Arctic zones, the southernmost representative was discovered off Belize. Image: NOAA Photo Library

Greenland sharks are still a mystery to science, with very little known about them. In addition to being probably the longest-lived vertebrates, it is also known that they are not pure deep-sea dwellers, but keep coming to the surface in a yo-yo diving motion to hunt. Their food spectrum is wide. However, due to their way of life, their metabolism is very slow and therefore they can go without food for a long time. But little is known about their reproductive strategies, how many young they can have, where their breeding sites are, and other information important to the conservation of the species. Ecologists believe that animals that can live that long might not make their first reproductive attempts until after 100 years and then be successful after 150 years. Nothing specific is known about their number either. All this makes the establishment of protective measures a challenge. But at least on the part of fisheries, a first important step has been taken. More are likely to follow and with the longevity of fish, they even might live to see it.

Dr Michael Wenger, PolarJournal

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