Strait of Hormuz: 1,500 Stranded Ships Threaten Global Plague

What happened?

The Strait of Hormuz, a vital passage for 20% of global oil traffic, officially closed on March 2, 2026 (though unofficially since February 28). Since then, more than 1,500 merchant ships have remained immobilized in the Gulf region, according to estimates by a team of 24 international researchers published in the journal Biological Invasions. This closure, the longest since the 1991 Gulf War, has driven crude oil prices up 40% in six months, according to data from the International Energy Agency. Ships that normally spend one to three days in port have now spent 40 times that—over 180 days—in Gulf waters, with their hulls stationary and accumulating unprecedented invasive biomass.

The biological problem

When a ship remains stationary for more than 10 days, biofouling—algae, mussels, larvae, and other organisms—attaches to the hull at an accelerated rate. The International Maritime Organization (IMO) recommends corrective action if inactivity exceeds 18-30 days. These ships have been idle for 40 times that threshold, accumulating unprecedented invasive biomass. The study in Biological Invasions estimates that each ship can harbor up to 10 tons of attached organisms, totaling 15,000 tons of potentially invasive biomass. For context, the largest documented bioinvasion event so far was the zebra mussel in the Great Lakes (1980s), which caused $5 billion in damages; the current one could surpass it in scale.

Dispersal routes

When they resume their voyages, the ships will carry these biological stowaways to ports around the planet. The study identifies the first ports at risk: Jeddah, Mumbai, Colombo, and Singapore to the east; Alexandria, Piraeus, Algeciras, and Rotterdam to the west. Environmental conditions similar to the origin facilitate the establishment of exotic species, which can displace native fauna, act as pathogen reservoirs, and cause epidemics. An alarming precedent is the European green crab (Carcinus maenas), which after attaching to ship hulls in the 19th century, invaded North American and Australian coasts, altering entire ecosystems. The current risk is greater: ships have spent more time accumulating organisms, and the routes cover ports with high global connectivity.

Economic and logistical impact

Meanwhile, some states are seeking alternative routes, such as the bypass through the desert of the United Arab Emirates, a colossal pipeline diverting up to 1.5 million barrels per day. The Spanish government applied measures to mitigate fuel price increases, such as reducing VAT to 10%, but has been gradually withdrawing them since June, according to Xataka. The reopening of the strait will not only ease energy pressure but also trigger a global ecological crisis. The cost of cleaning the 1,500 ships is estimated at $300 million (about $200,000 per ship), according to IMO calculations, but if no action is taken, damage to fisheries, tourism, and port infrastructure could amount to tens of billions.

“When they set sail, those ships are going to spread a plague across the planet,” the researchers warn.

What readers should know

The risk is not speculative: bioinvasion is one of the main causes of biodiversity loss, according to IPBES (Intergovernmental Science-Policy Platform on Biodiversity and Ecosystem Services). Port authorities and the IMO must activate hull cleaning protocols before the ships resume their routes. Otherwise, the ecological and health costs could exceed the economic cost of the closure. The study recommends mandatory inspections at key ports and the use of in-situ cleaning systems, such as underwater robots or high-pressure water sprays. The window of opportunity is narrow: if the ships set sail without treatment, the spread of invasive species will be virtually unstoppable.