Ships stuck in the Strait of Hormuz region may be biosecurity risks when they leave. What can we do?

Ships that have been stranded in the Strait of Hormuz region for months could pose a serious biosecurity risk once they resume operations, according to recent research. Over 1,500 commercial vessels have been laid up in the Persian/Arabian Gulf since February, accumulating marine biofouling species on their hulls. As the strait reopens, these ships may inadvertently spread these organisms to other ports, creating an international biosecurity “super-spreader” event. The potential consequences include harm to native ecosystems, wild fisheries, aquaculture stocks, and coastal industries, along with substantial environmental and economic damage. The issue of biofouling on idle vessels is not unique to the current situation. Researchers have noted that shipping disruptions, whether due to conflict, war, terrorism, piracy, or environmental conditions, often result in significant biofouling accumulation. In tropical waters, this process occurs rapidly, increasing the likelihood of invasive species being transported to new areas. The Strait of Hormuz, one of four major maritime choke points without alternative routes, exemplifies how such disruptions can lead to prolonged vessel layups. Global merchant vessel traffic plays a crucial role in transporting goods, with 24 key choke points identified in maritime trade. Of these, 20 have viable alternative routes, allowing for rerouting of vessels despite increased costs and delays. However, four choke points, among them the Strait of Hormuz, the Oresund Strait, the Bosporus and Dardanelles straits, and the Bohai Strait, lack alternatives. Disruptions at these sites can stem from various causes, including armed conflict, natural disasters, and human activities like piracy or deliberate layups. Deliberate vessel layups occur regularly, with approximately 1% of the global commercial fleet intentionally taken out of service. These layups are often driven by economic factors such as overcapacity, seasonal demand fluctuations, or the need for maintenance and upgrades. During periods of economic downturn, such as the global financial crisis of 2008, thousands of vessels were left idle, representing about 10% of container ships and 25% of refrigerated vessels. Similarly, the 1970s oil crisis saw 466 tankers laid up worldwide. Seasonal restrictions also contribute to vessel layups. Large fishing fleets, for instance, face regular shutdowns due to regulations or adverse weather. In the South China Sea, a conservation-related fishing closure between May and August leads to annual layups involving thousands of vessels. Fishing fleets in the North Pacific and Bering Sea similarly operate within limited seasonal windows, spending off-seasons in concentrated port areas. The implications of biofouling extend beyond immediate concerns. The Persian/Arabian Gulf hosts over 50 non-native marine species, some of which have already spread globally. While New Zealand and Australia are unlikely to see a surge of affected vessels in the first month following the Strait of Hormuz’s reopening, research indicates that numerous ships carrying potentially invasive species will arrive within a year. Both countries maintain robust biosecurity systems, including early detection mechanisms and rapid response protocols, to address such threats effectively. As the world continues to monitor the impact of the Strait of Hormuz disruption, the broader challenge of managing biofouling on idle vessels remains relevant. With ongoing shipping disruptions and the growing frequency of vessel layups, the risk of introducing invasive species through maritime activity persists. Addressing this requires coordinated efforts among nations, industry stakeholders, and regulatory bodies to mitigate the environmental and economic consequences of such incidents.