Ships stranded by war could cause marine ‘superspreader’ event, study warns

Scientists warn of unintentional risks from idle ships sitting for months in the Strait of Hormuz.

By Todd C. Frankel

New research warns that thousands of ships stranded for months by the ongoing war with Iran and the closed Strait of Hormuz could result in “a massive marine invasive species event.”

The study, led by scientists at the University of Maryland and the Woods Hole Oceanographic Institution, said the estimated 1,500 commercial vessels idled by war are likely now coated with marine microbes, algae and invertebrates.

The ships have sat submerged in the same waters for months, creating idle conditions for what the scientists call “biofouling.”

The scientists are now worried about what could happen when these ships eventually resume their journeys around the world. The study cites “the high likelihood” that the vessels will speed the spread of “economically and ecologically damaging invasive species.”

The threats posed by stranded ships are well-known and long-documented.

In 2023, the International Maritime Organization passed a resolution recommending that ships that sat idle for a period of typically 18 to 30 days take “immediate actions” to reduce the dangers of biofouling.

During World War II, ships from New Zealand that were held in English ports while waiting for escorts were blamed for spreading an Australasian barnacle to Western Europe. That invasive species threatened to outnumber native barnacle species.

The new study warned that current regulations are not enough to handle the potential impact from the large-scale, unplanned vessel stoppages caused by the war with Iran.

By Todd C. Frankel

Todd C. Frankel is a Pulitzer Prize-winning reporter on The Washington Post's Financial desk.