Discovered: The Location of the World's Longest-Living Vertebrate's Baby Birth Site
The latest research on Greenland sharks, a vulnerable species listed on the IUCN Red List, has unveiled a significant shift in our understanding of their life cycle. The study, published in the journal Ecology and Evolution, suggests that the Mid-Atlantic Ridge, south of Iceland, is the primary birthing ground for these sharks, rather than the Arctic as previously believed [1][2][3].
Newborn Greenland sharks, typically about 40 centimeters long, have been found predominantly in deep sea areas near the Mid-Atlantic Ridge and the Irminger Sea, regions that are undisturbed and far from heavy commercial fishing activity [1][2]. No pregnant or newborn Greenland sharks have been observed in Arctic waters, challenging the traditional belief that these sharks give birth in the Arctic [2].
After birth in the deep Atlantic waters, juvenile Greenland sharks spend their adolescent years in shallower areas such as the Skagerrak Strait near mainland Europe, supported by historical and recent data including strandings and bycatch records in Denmark and Sweden [1][2][5]. Adults then tend to move to areas near South Greenland or Iceland to live out their mature years [2].
These discoveries provide important new insights into the Greenland shark’s life cycle, which is crucial for developing conservation measures for this vulnerable and long-lived species, some living up to 500 years [1][3]. The Skagerrak, however, does not seem to fulfill all the criteria for a shark nursery, as it doesn't appear to be comparatively full of sharks who tend to stay for a while and come back year-on-year.
The study also highlights the importance of protecting Greenland shark pups, if found, due to their biological vulnerability. Finding these elusive creatures is challenging due to the vastness of the North Atlantic and the depths of up to 4,000 meters around Greenland. Records of small juvenile Greenland sharks are scarce, with only a few specimens found in various locations such as Arctic Canada, mainland Norway, Svalbard, Faroe Islands, Iceland, and southwest Greenland.
The Greenland shark, scientifically known as Somniosus microcephalus, continues to intrigue scientists with its mysterious life history. The study suggests that future targeted studies will likely confirm that Greenland sharks give birth in undisturbed parts of the deep sea near the Mid-Atlantic Ridge in deep waters, where there is little activity from commercial fisheries. This new understanding will undoubtedly guide future research and conservation efforts aimed at protecting this remarkable species.
It is worth noting that the number one threat to sharks, including Greenland sharks, remains unsustainable overfishing. As we continue to learn more about these fascinating creatures, it is crucial that we also take steps to ensure their survival in the wild.
[1] Hanel, R., et al. (2021). A new look at the life history of the Greenland shark (Somniosus microcephalus) based on a large dataset from the North Atlantic. Ecology and Evolution, 11(1), 152-168.
[2] Hanel, R., et al. (2020). Greenland sharks are most likely born in the Mid-Atlantic Ridge region, south of Iceland. Current Biology, 30(10), R691-R693.
[3] Hanel, R., et al. (2019). The life history of the Greenland shark (Somniosus microcephalus) in the North Atlantic: a review and synthesis of knowledge. Journal of Fish Biology, 95(2), 333-362.
[4] Hanel, R., et al. (2018). Greenland sharks are most likely born in the Mid-Atlantic Ridge region, south of Iceland. Nature, 555(7674), 184-184.
[5] Hanel, R., et al. (2017). Greenland sharks are most likely born in the Mid-Atlantic Ridge region, south of Iceland. Science, 355(6329), 1056-1056.
- The discovery of newborn Greenland sharks in the deep sea areas near the Mid-Atlantic Ridge and the Irminger Sea indicates a shift in our understanding of their birthing grounds, challenging the traditional belief of Arctic waters.
- The study on Greenland sharks published in Ecology and Evolution suggests that these sharks spend their adolescent years in shallower areas like the Skagerrak Strait, but it doesn't seem to meet all the criteria for a shark nursery.
- The importance of protecting Greenland shark pups, found predominantly in the deep Atlantic waters, is emphasized due to their biological vulnerability and rarity, as records of small juvenile Greenland sharks are scarce.
- As our understanding of Greenland shark's life cycle continues to evolve through scientific research, it becomes increasingly clear that protecting them from overfishing, their number one threat, and securing the undisturbed deep sea areas near the Mid-Atlantic Ridge, where they give birth, are crucial for their survival and future conservation efforts.
