Mako sharks, encompassing both the shortfin and longfin species, are among the swiftest apex predators inhabiting the open ocean. These highly migratory sharks traverse vast distances across temperate and tropical waters globally. Their presence reflects the health of marine ecosystems. Concerns about their population numbers highlight challenges facing many large ocean-dwelling species.
Current Population Estimates and Status
Estimating precise population numbers for mako sharks presents a challenge due to their vast oceanic habitats and migratory behaviors. Scientific assessments often rely on trends and models rather than absolute counts. In 2019, the International Union for Conservation of Nature (IUCN) classified both the shortfin and longfin mako sharks as globally Endangered, indicating significant population declines.
For the shortfin mako shark, the global population has experienced an estimated median reduction of 46.6%. While some regional populations, like that in the South Pacific, show signs of increase, most are declining. The North Atlantic shortfin mako population is considered overfished and is projected to continue declining for at least another 15 years, with recovery unlikely by 2070 under current management measures.
The longfin mako shark is rarer and less understood than its shortfin counterpart, often grouped together in fishery statistics. Despite limited specific data, its low reproductive rate and vulnerability to fishing practices have also led to its Endangered classification by the IUCN. Challenges in accurately assessing these populations are compounded by issues such as under-reporting of catches and the inherent difficulties of monitoring wide-ranging species.
Primary Threats to Mako Sharks
The primary factor behind the decline in mako shark populations is overfishing. These sharks are caught both intentionally and unintentionally in commercial fisheries, particularly in pelagic longline operations targeting species such as tuna and swordfish. The high demand for their meat and fins in international trade creates an incentive for their retention, even when they are caught as bycatch.
Mako sharks are vulnerable to overexploitation due to their biological characteristics. They exhibit a slow reproductive rate, reaching maturity late in life (females between 8 and 21 years). Their reproductive cycle is lengthy, with a gestation period of 15-18 months and relatively few pups per litter. This slow growth and reproductive cycle means that populations cannot quickly rebound from fishing pressure.
Conservation Initiatives and Management
International and national efforts are underway to protect mako sharks and facilitate their population recovery. Both shortfin and longfin mako sharks were listed on Appendix II of the Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITES) in 2019. This listing mandates that international trade in mako shark products requires permits, ensuring they originate from legal and sustainably managed fisheries.
The Convention on Migratory Species (CMS) also listed both mako species on Appendix II in 2008, obligating member countries to work regionally towards their conservation. For the North Atlantic shortfin mako, the International Commission for the Conservation of Atlantic Tunas (ICCAT) agreed in 2021 to a two-year ban on retaining, shipping, or landing the species. Scientists have consistently advised a complete ban on retention to aid recovery.
Ecological Significance of Mako Sharks
Mako sharks serve a role as apex predators within marine ecosystems. Positioned at the top of the pelagic food web, they consume a diverse diet including bony fishes, squids, and even other sharks, contributing to the regulation of prey populations. Their presence helps maintain the balance and health of these complex ocean environments.
Mako sharks occupy a high trophic level, indicating their importance in the flow of energy through the ecosystem. Their predatory activities influence the distribution and abundance of other marine species, which in turn supports overall biodiversity. The continued decline of these sharks could lead to cascading effects throughout the marine food web, disrupting natural ecological processes.