Shark and ray species are approaching endangerment stages globally.
Down deep: The perilous existence of deep-sea sharks and rays
The world's oceans hide a vast, uncharted realm, teeming with life yet mostly unexplored. The deep ocean, stretching beyond 200 meters, is home to an extraordinary assortment of species and yet remains a mystery. While this realm covers a vast area, it remains one of the least understood environments on our planet, with little comprehensive data available on its biodiversity and no policy-based indicators to guide conservation efforts. A recent study, published in The Conversation, highlights the increasing threat to deep-sea sharks and rays due to our expanding impact on the deep ocean.
Researchers have revealed that the number of threatened deep-sea sharks and rays has more than doubled between 1980 and 2005, largely due to the emergence and expansion of deep-sea fishing. From the bluntnose sixgill shark to the gulper shark, these fascinating creatures face a high risk of extinction due to overfishing for their meat and liver oil.
Deep-sea sharks and rays belong to a group of marine vertebrates that are particularly sensitive to overexploitation. Their long lifespans and slow reproduction make them akin to whales, which were once severely threatened by exploitation. Little action has been taken to protect deep-sea sharks, despite their known vulnerability and the lurking threat of overfishing.
The Greenland shark and the leafscale gulper shark hold population growth rates comparable to the sperm whale and the walrus, respectively. Yet, there are very few species-specific management actions for deep-sea sharks, leaving them vulnerable to the perils of our intrusive presence.
The lucrative market for deep-sea shark liver oil has driven targeted fisheries and accidental catch, further exacerbating the threat to these species. Some nations view deep-sea sharks and rays as a welcome catch due to the high value of their liver oil and demand for skate meat. This demand is not new, but it is the recent expansion and diversification of use, particularly for shark liver oil, that concerns conservationists.
Targeted shark liver oil fisheries are boom-and-bust operations, depleting shark populations rapidly and increasing the species' risk of extinction in short periods. Shark liver oil is increasingly sought after for applications in cosmetics and human health products, including vaccine adjuvants. However, there is little evaluation of the potential health risks associated with consuming liver oil, as deep-sea sharks accumulate heavy metals and contaminants at concentrations that surpass regulatory thresholds.
The global drive to protect 30% of the ocean by 2030 offers a glimmer of hope for deep-sea sharks and rays. Research shows that protecting 30% of the deep ocean (200-2000 m) would provide around 80% of deep-sea shark species with at least partial spatial protection across their range. Additionally, a worldwide prohibition of fishing below 800 m would provide 30% vertical refuge for one-third of threatened deep-sea sharks and rays. While these measures would help, they may not be enough to ensure the long-term survival of these remarkable creatures.
The fight to save deep-sea sharks and rays needs a concerted global effort. There is a critical need for trade and fishing regulations specific to deep-sea sharks and rays to prevent their further endangerment. Scientists urge the implementation of effective conservation actions in the deep ocean, establishing trade regulations and closures of crucial habitats for deep-sea sharks, to secure their place in our ocean for generations to come.
related content
You can explore more about fisheries in New Zealand, strategies to locate ships engaging in illegal fishing, and the roles of fishermen and conservationists in collaborative ventures. Discover the history of human impacts on marine environments, the concept of conservation rankings, and the importance of citizen science projects, like Spyfish Aotearoa, in furthering our understanding of marine species. Find valuable resources on the International Union for Conservation of Nature (IUCN) website, as well as articles on The Conversation that delve deeper into the challenges facing sharks and rays.
Useful Links
- IUCN website: https://www.iucn.org/
- The Conversation: https://theconversation.com/
- SAFE Shark and Ray program: https://safe-sharks.github.io/
- Global Coalition: https://www.theglobalcoalition.co/
- The concern about the escalating threats to deep-sea sharks and rays, as highlighted in a recent study published in The Conversation, is not limited to their habitat alone but extends to human health and wellness, particularly in the context of the growing demand for shark liver oil in cosmetics and health products.
- As we strive to safeguard the future of deep-sea sharks and rays, it is crucial to consider the broader impact on health and wellness, environmental science, and the conservation of medical-conditions related to heavy metals and contaminants that accumulate in their livers. Similarly, looking beyond climate change, a concerted effort in the realm of science and policy-making is essential to protect these vital species and ensure long-term biodiversity and health-and-wellness benefits.
