Shipping companies can get paid incentives if they're willing to slow down their vessels carrying cargo in and out of the port of Los Angeles to cut down on pollution and whale strikes, officials say.

In the voluntary effort developed by environmentalists, federal wildlife officials and air pollution regulators, the companies will receive payments for speed reductions in the Santa Barbara Channel off the coast of Southern California.

The program, in addition to reducing emissions, is intended to reduce strikes by ships responsible for the deaths of dozens of whales, included endangered humpback, fin and blue whales, threatening their recovery during the last 15 years.

The channel is a major feeding area for whales during their migrations along the U.S. West Coast.

Shippers willing to cut their usual cruising speed from 14 to 18 knots along the 130-miles stretch of ocean down to 12 knots or below will receive a $2,500 incentive per trip, officials said.

Slower speeds will have the dual benefit of allowing whales time to swim out of the way and avoid ships while the speed reduction will see the ships' giant engines emitting less pollutants.

"It's a very simple but clever solution: When you slow ships down you provide whale conservation and cleaner air for us to breathe here on shore," says Kristi Birney of the Santa Barbara-based Environmental Defense Center, one of the groups backing the effort.

Six international shipping companies have agreed to participate in a trial program running through October, which is the close of the peak feeding season for whales off the California coast.

The speed reductions will add about 4 hours to a typical cargo ship's trans-Pacific crossing, officials said.

Transponders on the ships will allow authorities to confirm that the ships kept their speed down to the reduced limit before authorizing the incentive payments.

The incentive program joins other efforts intended to reduce the impact of shipping on whale populations in coastal waters.

In June 2013 large cargo vessels using ports along the California coast were given modified traffic lanes designed to move them away from areas seeing the heaviest concentration of whales.

The changes affected traffic lanes leading to San Francisco Bay, through the Santa Barbara Channel, and to and from the ports of Long Beach and Los Angeles.

Even with the speed changes and the realignment of shipping channels, whales are likely to still remain at risk of ship strikes, environmentalists acknowledge.

Still, the incentive program should be worth the effort, they say.

"Now we're seeing if we can come to an innovative, collaborative solution before taking another path," Birney says.