Sharks are an ancient group of marine vertebrates, having navigated the oceans for over 440 million years and successfully survived five mass extinction events. These apex predators regulate marine ecosystems worldwide, yet their long evolutionary success is now jeopardized by rapid human pressures. The question of when sharks will go extinct reflects an urgency regarding the collapse of populations globally, transforming a theoretical concern into a present-day crisis for ocean health.
Current Conservation Status
Nearly one-third of all shark species are classified as threatened with extinction. According to the International Union for Conservation of Nature (IUCN) Red List, this includes species listed as Vulnerable, Endangered, or Critically Endangered. The severity of the decline is most evident in the open ocean, where oceanic shark and ray populations have plummeted by approximately 71% over the last 50 years.
Understanding the extinction risk requires distinguishing between numerical and functional extinction. Numerical extinction is the death of the last individual of a species. Functional extinction occurs much sooner, when a population is so reduced that it no longer performs its ecological role within the community. For sharks, this loss of influence as a top predator destabilizes the entire ecosystem.
Primary Drivers of Population Decline
The primary force driving the population collapse of sharks is commercial fishing, leading to high levels of overexploitation. This pressure stems from both direct targeting for meat and fins and the unintentional capture known as bycatch. Sharks are vulnerable to this exploitation due to their life history traits: they are slow to grow, mature late, and produce few offspring. This makes their populations unable to replenish at the rate they are being caught.
The demand for shark fins, particularly for use in traditional dishes, fuels the practice of finning, which contributes significantly to the population decline. The indiscriminate nature of fishing gear, such as longlines set for tuna and swordfish, also results in substantial shark bycatch. These longlines can extend for miles with thousands of baited hooks, catching sharks that are not the intended target species.
Secondary threats include habitat destruction and climate change. Coastal development destroys essential nursery grounds like mangrove forests, which young sharks need to survive. Ocean warming and acidification stress shark populations, as these animals are highly tuned to specific environmental conditions. These combined pressures accelerate the rate of decline, pushing more species toward threatened status.
The Ecological Ripple Effect
The removal of sharks triggers a trophic cascade, which is the sequence of indirect effects occurring when a top predator is removed from a food web. When sharks disappear, the intermediate predators they once controlled, called mesopredators, experience a population boom. This unchecked growth allows mesopredators to overconsume their prey, leading to a collapse of lower-level consumer populations.
A clear example occurred in the Northwest Atlantic, where the decline of large sharks led to an increase in cownose ray populations. The expanding ray numbers consumed so many bay scallops that they functionally terminated a century-old scallop fishery. Similarly, the loss of sharks in Caribbean reefs can lead to an increase in grouper, which then over-predates parrotfish. Since parrotfish graze on algae, their decline allows algae to dominate and smother corals, compromising the health of the reef system.
Global Stabilization Efforts
International agreements are focusing on regulating the trade and management of vulnerable shark species. The Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITES) is a major tool for conservation. CITES members voted to regulate the global trade of nearly 100 shark and ray species, including all requiem sharks and hammerhead species.
These CITES listings place the species under Appendix II, meaning international trade is permitted only with strict regulation to ensure sustainability and legality. This regulation covers over 90% of the global shark fin trade, providing a substantial framework for control. Beyond trade regulation, Marine Protected Areas (MPAs) offer localized refuges from fishing pressure, though their design must be improved to protect migratory species. Successful stabilization requires individual nations to implement strong regulatory reforms, establish science-based catch quotas, and enforce international agreements.