The massive container ships passing through the Santa Barbara Channel off the coast of Southern California will be paid a bonus of $2,500 per trip to slow down, in an effort to cut off-shore air pollution and reduce collisions with whales.

The four-month pilot program started in July, run by federal and local officials and an environmental group. It comes as the season for whales in the channel peaks.

Last week, a dead fin whale washed up at the beach and harbor city of Port Hueneme, south of Santa Barbara.

“Slowing down ships is a good thing for air pollution, endangered species protection and human health,” said Kristi Birney, marine conservation analyst with the Environmental Defense Center based in Santa Barbara.

Six shipping companies have agreed to participate in the program, which is backed by the National Oceanic and Atmospheric Administration (NOAA), the Santa Barbara County Air Pollution Control District and the nonprofit Environmental Defense Center, said NOAA policy analyst Sean Hastings.

The purpose is to combat exhaust emissions from the ships, which account for half of the ozone pollution in Santa Barbara County, and protect whales, often found washed up on the shore with blunt force trauma from collisions, Hastings said.

The timing coincides with the busiest whale-feeding season in the channel, and could save lives among endangered blue whales, Hastings said.

“The estimated population of blue whales in this part of the Pacific is 2,500, so every whale counts toward this population moving off the endangered species list,” Hastings said.

About 5,000 ships pass through the Santa Barbara Channel each year to the Los Angeles and Long Beach ports, a 130-mile (209-km) stretch.

Participating ships will be paid $2,500 for slowing to 12 knots during that part of the trip, from more typical speeds of 14 to 18 knots. A similar program targets air pollution at the Ports of Los Angeles and Long Beach.

A grant from the nonprofit Santa Barbara Foundation provided enough money to reward 16 slower trips, Hastings said.

The $2,500 bonuses will not be enough to fully cover the lost time to shippers who slow down, said Santa Barbara Foundation community investment officer Sharyn Main, but the agencies hope the incentive will still work.

“Nobody wants to hit these fabulous animals,” said Main, adding that the program was a way to reward shippers willing to try to avoid them.