Up to 5,000 cargo vessels visit the Ports of Los Angeles and Long Beach, the Number One and Number Two busiest ports in the Western hemisphere, on the Californian coast each year. From TVs to toys, clothing to cars, furniture to food – not to mention oil, coal, lumber and steel – the contents that giant container ships, vehicle carriers, bulk cargo ships and tankers deliver to the San Pedro port complex amount to more than 30% of all waterborne trade coming into the United States.

Whatever their cargo, the one thing each vessel brings with it is noise. “Shipping activity introduces underwater noise impacts on marine ecosystems and the sound-sensitive species that inhabit them,” says Jessica Morten, Director of Marine Resource Protection with the California Marine Sanctuary Foundation. “One of the biggest challenges we face with vessel traffic in important whale habitats is that the underwater noise many ships emit occupies the same frequencies as large baleen whales’ communications do, meaning even one noisy vessel can interfere with their ability to communicate, orient themselves, and find food.”

With international shipping increasing and many ports getting busier, it might seem that more damage to marine life is inevitable. “Introducing more traffic typically brings more harm,” agrees Morten. “But the good news is that a variety of solutions exist and are being tested and implemented around the world that reduce the negative environmental impacts of shipping, from vessel speed reduction measures (which is used to limit noise disturbance) to innovative propeller designs and wind propulsion systems.”

Over the last ten years, the Protecting Blue Whales and Blue Skies Program, administered by the California Marine Sanctuary Foundation, has worked with more than 50 global shipping companies to reduce the speeds of cargo vessels to 10 knots or less for over 1.5 million nautical miles in key blue, fin, and humpback whale habitats off of the California coast. The simple act of slowing down substantially reduces underwater noise. They’ve also worked with global shipping companies, such as Maersk-Line, to understand how noise can be reduced by design changes. “Reducing vessel noise has become a conservation priority for the International Maritime Organization (IMO), the global agency that governs maritime shipping,” Morten adds, “so there’s growing momentum and commitment from governments and industry to take action.”

Global shipping is just one anthropogenic (human-made) cause of underwater noise known to be negatively impacting marine life. There are many more, from military sonar to ‘piling’ (drilling or driving large steel or concrete columns into the ocean floor) to constructing offshore wind farms to sonic deterrents used by fish farms to keep away predators.

Oil drilling and exploration also create noise, including seismic blasting, used by oil companies to identify underwater oil reserves, where airguns blast noise to map the seafloor. “The high intensity noise harms marine mammals, such as whales,” explains Cooper Freeman, Alaska Director for the Center for Biological Diversity. “It can cause permanent and temporary deafness, which can make it impossible for whales to feed and communicate. A deaf whale is a dead whale.”