The Port of Los Angeles is holding back on extending its gate hours as encouraged by the Biden administration, focusing instead on boosting efficiency in operations while coping with a surge in imports into the critical U.S. trade gateway.

The decision, a contrast to the rapid adoption of 24-hour gate operations four days a week at the neighboring Port of Long Beach, highlights complications in the nascent Biden administration effort to address congestion in U.S. supply chains that is raising shipping costs and contributing to inventory shortages.

Gene Seroka, executive director of the Port of Los Angeles, said there is slack in the system that connects inbound and outbound containers to trucks serving inland distribution points. He said 30% of trucking appointment slots for transferring cargo go unused each day, on average, even as dozens of container ships gather offshore waiting for berths and port terminals process record volumes of inbound boxes.

“If that’s not going to be enough we will go to extended hours,” Mr. Seroka said. “But first I’d like to take care of where we are not working so well at the present time.”

The port’s gates are closed during the early-morning hours midweek and have limited hours on Saturdays. They are closed on Sundays.

Mr. Seroka said the port can extend operating hours only if trucking, warehousing and other industries also move toward 24-hour operations. ”You can’t hire labor, you can’t open terminal gates and tell everybody you are open for business and nobody shows up,” he said.

The side-by-side ports are run separately and compete with each other for ship calls. Port of Long Beach Executive Director Mario Cordero has vocally supported 24-hour operations as congestion has grown this year, while Los Angeles officials haven’t.

The Port of Long Beach has started operating 24 hours a day from Monday to Thursday, in response to encouragement from the White House, up from 16 hours a day previously. Mr. Cordero in a statement said the port was taking “bold and immediate action to help the supply chain” and expected to eventually expand the 24-hour operations to seven days a week.