Every year, in the waters off the California coast, hundreds of tankers, car carriers and container vessels from dozens of shipping companies take part in an unusual race.

To win, ships have to go slow.

Awards are given to companies whose fleets voluntarily reduce speeds in marine areas where endangered whales migrate through and feed in. The prize, known as Protecting Blue Whales and Blue Skies, comes with a sculptural whale-tail trophy and bragging rights.

“It’s good for the environment, and we make sure the public knows about it,” said Sean Hastings, a resource protection coordinator at the National Oceanic and Atmospheric Administration and a founder of the award program, which was created by a coalition of national marine sanctuaries, air quality districts and other nonprofit groups. “That’s the motivation right there.”

The real winner may be ocean life.

Program administrators say that the 2023 season, had the most participants ever — 33 companies. Eighty one percent of the total distance their ships traveled through the reduction zones was at the recommended speed of 10 knots or less, and that reduced the risk of fatal ship strikes to whales during the year by 58 percent. Slower ships also generate less ocean noise and fewer greenhouse gases and other air pollution.

“It’s like drivers slowing down in a school zone in the presence of schoolchildren,” Mr. Hastings said. “Every animal counts.”

About 90 percent of all consumer goods are shipped by sea, and the volume of maritime cargo has exploded in recent years, causing vessels to increase in size and numbers. The resulting traffic, pollution and underwater din have proven disastrous for marine life. Along the West Coast, an estimated 80 endangered blue, fin and humpback whales are killed by ship strikes annually, as warming waters caused by climate change shift their food sources closer to shore, where they can collide with ships.