An international team of marine scientists has raised alarm over more than 1,500 commercial ships stranded in the Strait of Hormuz due to prolonged conflict, warning they could become carriers of invasive marine species to ports across the globe.

The vessels, immobilized for nearly five months in the Persian Gulf and Gulf of Oman, have become heavily colonized by organisms such as algae, barnacles, seaweed, and bacteria. This biofouling poses a significant ecological risk, as these species can disrupt native marine ecosystems, harm fisheries, and increase maintenance costs for coastal infrastructure once the ships resume international trade.

The shipping disruption began on February 28, 2026, after US military strikes on Iran prompted Tehran to restrict commercial vessel passage through the strategic Strait of Hormuz, one of the world's busiest maritime trade routes. Despite intermittent reopenings during ceasefire talks, shipping activity remains far below normal levels, leaving many ships idle during peak breeding seasons for marine organisms.

Ecological and Economic Risks

  • Marine biofouling: Ships' hulls have become breeding grounds for invasive species due to extended inactivity.
  • Global spread: Once sailing resumes, these species could be transported to distant ports, threatening local biodiversity.
  • Economic impact: Invasive species can damage fisheries and increase port maintenance costs.

Mario Tamburri, lead author of the study published in Biological Invasions, described the situation as a potential "marine invasive species 'super-spreader' event." Co-author April Blakeslee emphasized the lasting environmental and economic consequences of such introductions.

Calls for Preventive Measures

The International Maritime Organisation (IMO) recommends biofouling management for ships idle over 30 days. However, many stranded vessels have exceeded this threshold multiple times, increasing the risk of established invasive communities.

Scientists urge ship operators, port authorities, and environmental agencies to:

  • Assess biofouling levels before vessels depart.
  • Identify high-risk destination ports.
  • Enhance monitoring and rapid response capabilities at vulnerable locations.
  • Improve information sharing to detect invasive species introductions early.

Without coordinated action, the resumption of shipping through the Strait of Hormuz could trigger a widespread ecological crisis affecting marine life and coastal economies worldwide.