Iran-US tensions threaten whales off South Africa

Global shipping lanes have shifted significantly since late 2023 when Houthi rebels began attacking vessels in the Red Sea. Subsequently, tensions at the Strait of Hormuz, blockaded by Iran, have forced shipping companies to reroute around South Africa's Cape of Good Hope. This change has drastically increased vessel traffic off the country's southwestern coast.

According to a study presented at a meeting of the International Whaling Commission (IWC), this has significantly raised the risk of collisions between ships and whales. Data from the International Monetary Fund shows that from March 1 to April 24, at least 89 commercial ships rounded South Africa, up sharply from 44 during the same period in 2023.

South African waters are home to more than 40 whale species. Large groups of humpback whales often feed in this area before their annual migration to Antarctica, with a total population estimated between 11,000 and 13,000. Other species such as the Antarctic blue whale, fin whale, and sei whale remain listed as Endangered or Critically Endangered on South Africa's Red Data List.

Researcher Els Vermeulen from the University of Pretoria, lead author of the study, said crew members on cargo ships often film passing dense whale pods with enthusiasm, but she realized that meant the ship was hitting many whales. Fast ship speed – the most dangerous factor – has quadrupled. Whales often don't perceive the danger, especially when they are focused on feeding.

Chris Johnson, global expert for the World Wildlife Fund, noted that whale species have not learned to adapt to ships. For instance, blue whales off Los Angeles, when hearing an approaching vessel, simply dive deeper instead of moving away. Additionally, climate change-induced behavioral shifts have caused humpback whales to only start feeding along the western coast – where ship traffic is increasing – from 2011 onward.

An earlier study by Vermeulen's group, published in 2022, recorded that from 1999 to 2019, among 97 deaths of southern right whales off the Western Cape coast, 11 were caused by ship strikes. Scientists believe this number is underreported because many whales struck in open ocean sink to the seafloor.

To protect whales, Vermeulen's research suggests that a slight shift of shipping lanes farther offshore could reduce collision risk by 20 to 50 percent. Swiss company MSC has already begun rerouting vessels to protect critical whale habitats in Greece and Sri Lanka. Other measures include speed reduction programs, radio alerts about large whale aggregations, or the use of specialized apps.

South Africa's Department of Environmental Affairs said it will consider all feasible solutions and mitigation measures to protect whales at the Cape of Good Hope. After scientific studies and assessments are completed, maritime authorities will coordinate with the department to determine the next steps.