Over the past two decades, regulations have increased regarding fishing for sharks, rays, and marine mammals. However, some deep-sea sharks and stingrays seem to slip through the nets. These pelagic sharks are now endangered, according to a study led by New Zealand doctor Brittany Finucci from the National Institute of Water and Atmospheric Research (NIWA) and her team, published in the journal Science.
And yet these deep-sea animals, highly prized for their liver oil and meat, are not protected. Despite international commitments to protect 30% of the world’s oceans, there are no relevant indicators to guide the setting or monitoring of conservation targets on a global scale. To address these gaps, Brittany Finucci and her colleagues calculated indicators of global biodiversity change, status and threats facing deep-sea sharks and rays. This study provides a global overview of the diversity of deep-sea sharks and rays, which often receive too little attention.
The high seas: an ecosystem threatened by overfishing
The open sea, more than 200 meters deep, is one of the largest and most complex ecosystems on the planet. Covering 84% of the world’s ocean surface and 98% of its volume, it is home to a great diversity of species. The pelagic zone is considered the last natural refuge of biodiversity protected from human activity, but at the same time remains one of the least explored environments on Earth. Without relevant indicators to guide the capture of the species targeted by the fishery, it then becomes a vulnerable ecosystem.
This phenomenon is worrying because the numerous regulations regarding the fishing of sharks and rays do not slow down this phenomenon. A study published in the journal ScienceOn January 11, 2024, it estimated that total shark mortality from fishing between 2012 and 2019 was at least 76 to 80 million individuals, of which approximately 25 million were endangered species. In addition, shark mortality in coastal waters is estimated to have increased by 4%. An alarming observation, but not from yesterday. In January 2021 revision Nature published a study on the overfishing of oceanic sharks and rays, in which researchers noted that since 1970, the global abundance of these stocks has declined by 71% as relative fishing pressure has increased 18-fold. And in this race for extinction, the ocean is no exception.
Also read: Sharks were killing at an alarming rate despite regulations
Shark liver oil: the heart of the hunt
One of the main causes of the rampant hunting of these animals is shark liver oil and their meat. This valuable squalene product has been used for many purposes for years. First used as a source of heating fuel and for ship maintenance, liver oil is still used today. This extract can be found in dietary supplements, cosmetics and also as a vaccine adjuvant as it aids the immune response. Although there are other plant-based and synthetic sources of squalene, animal-based squalene is preferred because of its high yield and better efficacy.
“Sharks have slow growth, late puberty and low fecundity”
But it’s true, most sharks are susceptible to overfishing because of their life cycle: “It is well documented that sharks, for example, have slow growth, late puberty and low fecundity. Deep sea sharks are no exception and generally have even more extreme life cycles“, develops Dr. Brittany Finucci of the National Institute for Water and Atmospheric Research (NIWA). This makes them more vulnerable to overfishing, even in small numbers, and less likely to recover. The study director adds that ““Some deep-sea sharks can take decades to mature and only give birth to one or two pups every few years.”. In some ways, some deep-sea sharks are more like marine mammals trying to resist and recover from exploitation.
In spite of,”“Many marine mammals have been protected for years, even decades, while deep-sea sharks remain largely unprotected.” Dr. Finucci is concerned. For example, the Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITES) has yet to see a proposal to list a deep-sea shark or stingray.
“One in seven species is threatened with extinction”
To address the accumulated gaps, Brittany Finucci and her colleagues calculated indicators of global biodiversity change, status, and threats facing deep-sea sharks and rays. Using the most comprehensive assessment of this group, including all 521 species of deep-sea sharks and rays, study researchers were able to estimate the sensitivity of the group relative to other exploited marine vertebrates. They also analyzed trends in their relative abundance and assessed their global extinction risk and underlying patterns of use and trade.
Using the International Union for Conservation of Nature’s Red List of Threatened Species, the study shows that the number of endangered deep-sea sharks and rays more than doubled between 1980 and 2005 following the establishment and expansion of fisheries in these waters.
Their findings are clear: a third of endangered deep-sea sharks are targeted for fishing, and half of the species targeted by the international liver oil trade are at risk of extinction. Sharks and rays in the pelagic zone are among the marine vertebrates most vulnerable to overexploitation. “We estimate that one in seven species (14%) is at risk of extinction.”reveals Dr. Finucci.
A call to action to protect deep sea sharks
This work highlights the importance of identifying and protecting important areas specific to deep-sea sharks and rays. “These areas may include spawning or mating areas or places where we know deep-sea sharks congregate.”, notes research director Dr. Brittany Finucci. “By protecting them, we can offer deep-sea sharks a refuge from human activities.”she says.
In addition, the study’s researchers are calling for increased national and international regulations. within the country, They support deep-sea shark fishing reporting and reporting by species at the national level to monitor stocks. Globally, the study’s scientists recommend the creation of trade regulations to ensure that all shark products come from legal, sustainable and traceable sources.
“There have been huge triumphs in shark conservation, but deep-sea sharks have been excluded from conservation debates” concludes Dr. Brittany Finucci.
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