The Staggering Numbers
Estimates for global shark mortality vary widely due to data collection challenges. Scientific studies suggest that approximately 73 to 100 million sharks are killed annually. This translates to a rate of over 11,400 sharks per hour. Some reports even indicate that the annual mortality could be as high as 273 million.
These figures are derived from various sources, including scientific papers published in journals like Science and Marine Policy, as well as data compiled by conservation organizations. Researchers often use catch data from fisheries across many countries, computer modeling, and expert interviews to arrive at these estimates. However, accurately tracking shark mortality is complex, as underreporting in fisheries is common, and some fishing activities, like illegal, unreported, and unregulated (IUU) fishing, are difficult to monitor.
Despite protective legislation, shark mortality increased from 76 million in 2012 to 101 million by 2019, highlighting ongoing pressure. Fewer than 10 people worldwide are killed by shark attacks annually, underscoring that sharks face a far greater threat from humans.
Primary Causes of Shark Deaths
Most shark deaths result from human activities, primarily commercial fishing. Targeted fishing for shark meat, fins, cartilage, and liver oil drives a significant portion of this mortality.
Demand for shark fins, particularly for shark fin soup, historically fueled a lucrative trade. This led to “finning,” where fins are removed, often while the shark is alive, and its body is discarded back into the ocean to die from suffocation, blood loss, or predation.
Sharks are also frequently caught unintentionally as “bycatch” in fisheries targeting other marine species like tuna or swordfish. Fishing gear such as longlines, gillnets, and bottom trawls ensnare sharks, and many are discarded, injured, or already dead by the time they are brought aboard. This accidental capture contributes heavily to the decline of numerous shark species, especially those with slow growth rates and low reproductive output.
While less prevalent globally, some regions implement culling programs where sharks are killed for perceived public safety concerns, often following shark incidents. Such programs are controversial and widely criticized by conservationists for their limited effectiveness and negative ecological impact.
Illegal, unreported, and unregulated (IUU) fishing significantly exacerbates shark mortality. IUU fishing operations often disregard quotas, protected areas, and species bans, leading to unrecorded and unsustainable catches that undermine conservation efforts and make accurate population assessments difficult.
Impact on Marine Ecosystems
As apex predators, sharks regulate populations below them, maintaining balanced ecosystems. When shark populations decline, it can trigger a phenomenon known as a “trophic cascade.” This means removing top predators can increase prey species, which then overconsume their food sources, causing ripple effects throughout the food chain.
For example, a decline in sharks can lead to an increase in mid-level predators like rays and skates. These animals may then consume excessive amounts of shellfish, impacting the health of commercially important fisheries and coastal habitats like seagrass beds and coral reefs. Sharks also play a role in maintaining the health of coral reefs by preying on herbivores that, if left unchecked, could overgraze algae and harm coral growth.
The loss of sharks affects not only other fish but also the structure and function of ocean habitats. Over time, these imbalances can lead to less diverse and less productive marine environments.
Conservation and Action
Addressing shark mortality requires a multi-faceted approach: international cooperation, policy changes, and public engagement. International agreements, like CITES, regulate trade of threatened shark species by listing them in appendices that control or ban commercial trade. Many countries have also enacted national regulations, including fishing quotas and bans on shark finning, though their effectiveness varies.
Promoting sustainable fishing practices is another important step. This includes the development and use of bycatch reduction devices that allow sharks and other non-target species to escape fishing nets. Encouraging responsible seafood choices by consumers can also reduce demand for unsustainably caught shark products. Certifications for sustainable fisheries help guide consumers toward options that minimize environmental impact.
Establishing Marine Protected Areas (MPAs) creates safe havens where sharks can thrive without fishing pressure, allowing populations to recover and spill over into surrounding areas. These protected zones can be particularly effective for species with limited ranges or those that aggregate in specific locations. Public awareness and education campaigns are also important for changing perceptions about sharks and discouraging the consumption of shark products. By understanding the ecological value of sharks and the threats they face, individuals can contribute to conservation efforts through advocacy and conscious consumer choices.