A groundbreaking global study has shed light on the precarious situation facing deepwater sharks and rays. Led by a team of experts from around the world, the study reveals alarming statistics: one in seven deepwater sharks and rays are on the brink of extinction, according to the criteria set by the International Union for Conservation of Nature Red List of Threatened Species.
The primary threat to these deepwater giants is one similar to their shallow-water counterparts: overfishing, particularly as unintended victims of commercial fisheries targeting other species. Their meat and liver oil are prized commodities, driving a global trade that is pushing these creatures to the edge of oblivion. What makes deepwater sharks and rays particularly vulnerable is their unique biology. Spending most of their lives in the dark depths, these creatures have evolved to endure the harsh conditions of the abyss. However, their long lifespans and slow reproductive rates make them highly susceptible to overexploitation. “Many deepwater sharks and rays can only withstand very small amounts of fishing pressure”, said Dr. Nicholas Dulvy, Professor at Simon Fraser University. “Some species may take 30 years or more to mature, and possibly up to 150 years in the case of the Greenland Shark. Some only produce 12 pups throughout their entire life. Because of their relatively large size and widespread distribution, deepwater sharks and rays play a vital ecological role, concentrating and dispersing nutrients throughout deep ocean habitats.”
Dr. Rima Jabado, Deputy Chair of the IUCN Species Survival Commission and Chair of the IUCN SSC Shark Specialist Group, stresses the urgent need for action: “Our results highlight that it is time to think about regulating liver oil trade. There has been enormous success in regulating the shark fin trade but trade and fishing regulations specific to deepwater sharks and rays are urgently needed. […] Deepwater sharks and rays have been out of sight, out of mind for too long. Now is the time to take action to prevent further endangerment.” Jabado urges for specific regulations tailored to protect these creatures, including national protections, fishing regulations, and listing species under international trade agreements like CITES.
Shockingly, this study indicates that approximately 14.1% of these deep-sea dwellers face an elevated risk of extinction on a global scale. Among the 521 species scrutinized, a concerning 60 (11.5%) are currently identified as threatened, comprising nine (1.7%) Critically Endangered, 20 (3.8%) Endangered, and 31 (6.0%) Vulnerable species. This level of extinction risk represents a stark increase compared to the previous assessment conducted in 2014, more than doubling the reported threatened species count. Notably, deepwater sharks demonstrate a particularly dire situation, with 15.2% (43 of 283 species) classified as threatened, compared to deepwater rays at 7.1% (17 of 238 species). Despite the absence of species flagged as Possibly Extinct or assessed as globally Extinct or Extinct in the Wild, the phenomenon of “commercial extinction” poses a substantial threat, particularly observed among gulper sharks in regions of intense targeted fishing. Nevertheless, a significant portion of species (62.0%, n = 323) remain classified as Least Concern, while 43 species (8.3%) hover dangerously close to the brink, designated as Near Threatened. The authors believe these findings underscore the urgent need for concerted conservation efforts to safeguard the future of deepwater sharks and rays, whose decline could have profound implications for marine ecosystems worldwide. While deepwater sharks and rays are often forgotten about, their importance extends far beyond their formidable presence in the punishing depths of our ocean. These creatures play a vital ecological role, dispersing nutrients and maintaining the delicate balance of deep ocean habitats.
The researchers also explored two strategic approaches aimed at halting and reversing the declines observed among threatened deepwater sharks and rays, aligning with the Convention on Biological Diversity’s “30 by 30” framework of spatial protection commitments. The first approach evaluates the advantages of implementing a global depth limit, restricting fishing activities below a designated depth (referred to as vertical refuge). The second approach assesses the benefits of establishing spatial no-take areas (referred to as horizontal refuge). A worldwide prohibition of fishing beyond 800 meters would offer 30% vertical refuge, safeguarding approximately one-third (27.4%) of threatened species. Alternatively, setting a shallower 500-meter no-fishing limit would effectively double the protection coverage, encompassing 60.8% of species. Protecting 30% of the deep ocean between 200 and 2000 meters would extend spatial (horizontal) protection to approximately 80% of species, spanning their ranges. Notable regions with significant coverage include the Gulf of Mexico and Caribbean Sea, Eastern Pacific (from western United States to Peru), Iberian Peninsula, southern Mediterranean Sea, Gulf of Aden, west India and Chagos-Laccadive Ridge, Sea of Japan and Sea of Okhotsk, and the Zealandia continent.
“Trade and fishing regulations specific to deepwater sharks and rays are needed to ensure legal, traceable, and sustainable trade and prevent further endangerment,” the team concludes. “We have the evidence to act more proactively for the deep ocean and learn from the mistakes that have driven more than half of coastal and pelagic species to be threatened. Achieving sustainable fisheries for most deepwater sharks and rays would be challenging and require high management capacity, ecological knowledge, and implementation of routine rigorous monitoring. [However,] effective precautionary actions are needed to ensure that the largest ecosystem on the planet maintains its biodiversity and that half of the world’s shark and ray species have refuge from the global extinction crisis.”
