Fear for Florida Ecosystems: Sharks & Rays at High Risk of Global Extinction, New Study Finds

A school of anthias (Pseudanthias bartlettorum) and a school of white tip sharks at Jarvis Island. Cover photo for illustrative purposes only. Photo by: NOAA Photo Library | Flickr

A coauthored study between the National Oceanic and Atmospheric Association (NOAA) and a board of researchers and scientists has uncovered a significant risk of global extinction for some of the ocean's most misunderstood sea creatures: sharks and rays. Though considered by most a dangerous, tough, and voracious predator, evidence shows sharks and other cartilaginous fish fill many niche roles that play an important part in keeping the balance in deep-sea ecosystems — a balance that is in danger of being disrupted and even eliminated completely.

The study, published in the Science journal on December 6, 2024, quantifies the extinction risk for the world's 1,199 sharks and ray species over 50 years, and has uncovered a rough state for these creatures on a global scale.

By developing and establishing a 50-year Red List Index (RLI) of sharks and rays — a sustainability guideline used by the UN Sustainable Development Goals, the Convention on Migratory Species, and other organizations — scientists and the NOAA have been able to chart how extinction risk has expanded across geographic, bathymetric, and biodiversity axes, and have mapped the bright and dark spots that support or inhibit conservation efforts for these crucial ecological warriors.

Scientists were also able to estimate ecological erosion and the decline of ecological function embodied in threatened species while also identifying the key ecological, socioeconomic, and fishery issues that drive extinction risks to new heights.

"We found that sharks and rays globally are in a worse conservation state than all other vertebrate groups, apart from amphibians," say the NOAA. "We also demonstrated the fishing down of shark and ray biodiversity and ecosystem function. This shows that the largest species declined first and most rapidly."

According to the NOAA, most sharks and rays have shown slow population growth rates, which makes them highly vulnerable to the effects of overfishing, and subsequently, their populations struggle and take longer to rebuild — a problem largely attributed to declining food resources as a result of overfishing and incidental bycatch by commercial fisherman.

According to the study's data, global shark and ray populations peaked in the late 1980s, but has remained stagnant and on steady decline since.

Since 1970, overfishing has halved shark populations, causing a 19% decline in their RLI. Overfishing is particularly prominent for the largest species found in nearshore habitats; however, data shows that open-ocean habitats are also at risk of loss of these 1,199 different shark and ray species, showing an estimate of 5 to 22% erosion of functional diversity imminent over the coming years.

The overfishing problem has also had its impacts on other deep sea species, such as the critically endangered North Atlantic right whale, which has fewer than 370 estimated individual whales remaining today, with fewer than 70 of those tracked as being actively able to reproduce females.

Global shark and ray RLI for tracking progress toward global biodiversity and sustainability targets. The global reconstructed catch of all chondrichthyans peaked in the late 1980s and has been stagnant ever since, despite a doubling of fishing effort. This is likely due to increasing unsustainability and population collapse, which has resulted in greater numbers of species at risk of extinction, as revealed by declines in the RLI since 1970. Over time, the RLI continued to decline owing to the serial depletion of the largest most functionally important sharks and rays, some to the point of local extinction (sawfishes and other rhino rays), before fisheries sequentially depleted large stingrays, eagle rays, angel sharks, hammerheads, and requiem sharks. As a result, there is an increasing representation of smaller individuals and species in catches. An RLI value of 1 indicates that a given taxa qualifies as IUCN Red List category Least Concern (that is, not expected to become extinct in the near future), whereas an RLI value of zero indicates that all taxa have gone extinct. mt, metric tons.

But overfishing and bycatch aren't the only risks to survival these elegant predators of the deep face; sharks and rays around the world are often targeted for their coveted fins, meat, gill plates, and liver oil, which when done en-scale, poses risk of ecological erosion and biodiversity loss, and could have devastating effects in both the short and long term.

Ecological erosion, the process of losing key species that provide an important ecological niche, could cause a domino effect to cascade across marine ecosystems. Further loss of biodiversity and ecosystem function would be detrimental not only to these species survival, but to the prosperity of humanity — as billions of people around the globe rely on oceans as a direct source of nutrition and for streams of income.

Other risks to conservation efforts for these sharks and rays have been on the rise over recent years too, including increasing loss of coastal habitats and reefs, poleward shifting of some species as a result of climate change and rising ocean temps, and sublethal effects of global pollution.

However, the full scale of detriment to biodiversity and ecosystem function that has diminished over the past half-century is not quite as clear as science would hope, as they admit that the true state of ocean biodiversity can be difficult to completely assess.

Overall, researchers and the NOAA state that extinction risks vary greatly, with risk higher in countries with larger human coastal populations and higher fishing pressure. Lower risk is observed in nations with stronger governance that trade at sustainable levels in combinations with prohibiting the retention of highly-threatened species to further avert depletion of crucial oceanographic resources, biodiversity, and top-down predator control, as well as widespread loss of population communication and connectivity.

Shark and ray fisheries management and conservation efforts have increased in the past decade. According to the NOAA, this includes international trade regulations for more than 143 shark and ray species that encompass more than 85 percent of the global fin trade.
While the NOAA say that notable progress in the appreciation and conservation of sharks and rays has been made, they recognize that chronic under-assessment and undermanagement of fisheries is widespread, particularly in countries with weaker governments. Science-based fishery catch limits and measures to minimize incidental catch, including spatial protections, will be essential to ensuring the sustainability and recovery of these species and their ecological, social, and economic potential.

The closer to the RLI of 0 to 1 we get, the higher the risk of global extinction for these species; current RLI numbers sit at approximately .6 for sharks and rays. Scientists and researchers with the NOAA recommend the adoption of shark and ray RLI on a global scale to track progress toward both the Kunming-Montreal Global Biodiversity Framework target of an RLI of 5, and the United Nations Sustainable Development Goal of 14.1.

Florida's oceans are widely recognized as hot spots for roaming sharks that call the coast home, as well as for visits from migrating species of sharks, year-round; while the risks are still something for concern, as migration and population numbers could easily fade as the threat of extinction treads closer, Florida's shark conservation efforts appear to be making a positive impact — with the Florida Fish and Wildlife Conservation Commission (FWC) limiting shark harvests to one per person per day and only two per vessel, use of only a rod and reel in catches, requiring permitting for catching, selling and purchasing sharks, and the banning of harvest, possession, landing, purchase, sale, or exchange of 25 of the most at-risk shark species.

Despite the difficulty in quantifying the exact number for shark populations swimming around Florida waters, local Sunshine State experts have seen a rebound in recent years. Fishing charters have noticed an anecdotal increase in population activity, citing problems with sharks regularly intercepting their catches.

A biologist working toward shark conservation at the Mote Marine Laboratory, Valerie Hagan, has also been quoted in the last year as seeing a rebound in some species of shark's estimated populations since the legislation and enforcement of laws focused on conservation — showing that Florida's efforts are a testament to the possibility of protection with continued effort improvements and changes on a global scale.

One such improvement that could be made to help solidify Florida's spot as a safe space for dwindling shark populations — the elimination of shark fishing tournaments. To this day, they still happen fairly regularly across the Sunshine State, and contribute to the overfishing of an already declining population. While the government does not outwardly condone them, they do allow these controversial killings-for-sport to continue despite evidence of global extinction being a serious possibility.

Despite there still being challenges to overcome, today, the NOAA proudly acknowledges the United States as a whole as home to some of the largest and best-managed marine fisheries in the world, opening up doors to opportunity and responsibility to further advancement of the conversation around sustainable management practices on the high seas.

The United States also has the chance to further support other nations in achieving similar outcomes in their economic zones. The NOAA Fisheries say they hope that science-based conversation and management of sustainable fisheries will continue to grow adaptation of global models for marine stewardship and sustainability with time.

Article by Rachael Volpe