Sharks, creatures that have survived for over 400 million years, face an urgent conservation crisis driven entirely by human activity. The widespread fear surrounding these ocean predators stands in stark contrast to their vulnerability to modern fishing practices. This massive removal of sharks from the marine environment represents a significant threat to the overall health of the global ocean ecosystem. Understanding the scale of this mortality is the first step toward grasping the profound impact humans have on these species.
The Annual Shark Mortality Figure
The number of sharks killed by humans each year is staggering, historically averaging around 100 million. This estimate stems from a landmark 2013 study published in Marine Policy, which provided the first comprehensive global assessment of shark mortality. The research calculated an annual range of deaths between 63 million and 273 million sharks, with 100 million representing a median estimate for the year 2000.
The wide range in scientific estimates highlights the difficulty in accurately calculating the total number of deaths. Global fishing data is often incomplete, making it challenging to track unreported landings, illegal fishing activities, and sharks discarded at sea. A more recent analysis focusing on 2012 to 2019 suggests the figure may have slightly decreased to approximately 80 million sharks killed annually, though this number remains unsustainable.
Scientists calculate these figures by combining officially reported catch data from organizations like the United Nations Food and Agriculture Organization with projections for unreported catch. This high rate of exploitation is damaging because most shark species grow slowly and mature late, producing few offspring. The current rate of removal far exceeds the natural ability of many shark populations to replenish themselves, pushing numerous species toward extinction.
Primary Causes of Shark Mortality
Human-caused shark mortality falls into two main categories: targeted fishing and accidental capture (bycatch), both contributing tens of millions of deaths annually. Targeted fishing is driven by international demand for shark products, particularly fins used in shark fin soup. Shark finning involves removing the fins and discarding the often-still-living body back into the ocean, where the shark typically dies from suffocation or blood loss.
Although numerous countries have implemented finning bans, demand remains a powerful economic driver. An estimated 73 million sharks are killed annually specifically to supply the global fin trade. The fins are highly valuable, leading to a wasteful practice where the less valuable carcass is often dumped. The growing market for shark meat, liver oil, and cartilage further incentivizes targeted catch.
The second major cause is bycatch, the unintentional capture of sharks by industrial fishing operations targeting species like tuna or swordfish. Fishing gear such as longlines, which can stretch for miles with thousands of baited hooks, and large gillnets are indiscriminate. Sharks caught in this gear are often dead or dying by the time the lines or nets are retrieved and are then discarded. This unintended mortality accounts for tens of millions of deaths, significantly contributing to population decline, especially since many commercial fisheries underreport this accidental catch.
Ecological Consequences of Population Decline
The massive reduction in shark numbers represents a fundamental threat to the stability of the marine food web. Sharks function as apex predators, meaning their removal triggers a trophic cascade. This is a ripple effect that occurs when a top predator population is removed, altering the abundance and behavior of species at lower levels.
When sharks are removed, their direct prey—often mid-level predators like smaller fish or rays—experience a release from predation pressure, allowing their populations to explode. For instance, overfishing large sharks in the North Atlantic led to a population boom in cownose rays. The increased ray population subsequently over-consumed their prey, the bay scallop, which caused the collapse of a centuries-old local scallop fishery.
In coral reef environments, the loss of sharks can allow larger predatory fish to thrive, which then consume significant numbers of herbivorous fish like parrotfish. Parrotfish graze on algae that would otherwise smother and kill the coral. Therefore, the reduction of sharks ultimately leads to the degradation of the entire reef system. The stability of the marine ecosystem relies on the presence of these top predators to regulate populations and maintain balance.
Global Conservation and Mitigation Efforts
Addressing the scale of shark mortality requires coordinated action across international governance, national policy, and consumer markets. Global conservation efforts rely on international agreements like the Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITES). CITES regulates the cross-border trade of vulnerable species and has listed several commercially exploited sharks, including oceanic whitetips and various hammerheads. This forces member nations to ensure that any international trade is sustainable.
Regional Fisheries Management Organizations (RFMOs) also play a large role. They are tasked with setting science-based catch limits and implementing conservation measures for shared fish stocks across large ocean areas. These regional bodies work to enforce regulations and promote the use of selective fishing gear to reduce accidental shark bycatch. They are also encouraged to adopt the “fins naturally attached” policy, which requires fishermen to land sharks with their fins still attached. This makes it easier to enforce finning bans and collect species-specific data.
At a national level, a growing number of countries, including the United States and the European Union, have implemented specific bans on the sale and trade of shark fins. Consumer choices and market mechanisms are helping to shift demand away from unsustainable fishing practices. The increasing value of the shark meat trade, however, presents new challenges, demonstrating the need for comprehensive, enforced management strategies that address all sources of shark mortality.