Shipping company Maersk Line on Monday announced an agreement with the Ports of Los Angeles and Long Beach to monitor emissions from 12 recently upgraded container vessels that use the ports.

The monitoring equipment, part of a $125 million environmental upgrade for the ships, will track vessel emissions and energy efficiency over the next three years.

“This is the equivalent of strapping a Fitbit onto a large container ship,” said Lee Kindberg, director of environment and sustainability for Maersk. The Copenhagen, Denmark shipping line is the world’s largest, with 630 container vessels.

All 12 Maersk vessels are capable of plugging into shore side power when berthed at terminals at the two ports. The already completed environmental upgrades included redesigning the ships’ bows and replacing propellers with more efficient models.

The two ports will contribute a total of $1 million from their joint technology advancement program to the monitoring effort.

“This project is an example of the deep commitment to environmental sustainability that we have grown to expect from our goods movement partners,” said Duane Kenagy, interim chief executive at the Port of Long Beach. “We hope it will serve as a model to encourage even more progress and creativity in emissions reductions from oceangoing vessels.”

Public policy and energy reporter Howard Fine can be reached at [email protected]. Follow him on Twitter @howardafine.