LOS ANGELES — Port clerks returned to work Wednesday, jubilant in the knowledge that an eight-day strike that paralyzed the nation's busiest shipping complex had won them — at least for now — guarantees that their jobs won't be outsourced to China, Arizona or other places.

The 600 clerical workers at the ports of Los Angeles and Long Beach represented by the International Longshore and Warehouse Union won only modest increases in wage and pension benefits over the life of a new four-year contract.

But more importantly, said union spokesman Craig Merrilees, they extracted promises from management that, as workers retire or leave the ports during the next four years, no more than 14 jobs will be outsourced. Companies also must continue to fill vacant positions when workers are absent for vacations or other reasons.

"The key issue in this whole strike was the outsourcing of good jobs, and they won protections against outsourcing abuses," Merrilees said.

He acknowledged that the issue would likely be front and center in negotiations when the new contract expires in 2016.

Shippers denied outsourcing jobs, but strikers insisted they had proof.

Trinnie Thompson, a union shop steward, said workers have seen invoices and emails showing some of their responsibilities being usurped by people in offices in Costa Rica, Shanghai, Colorado and Arizona.

"They take a job here in California where the average salary is $65,000 and are paying only $30,000 in a state like Arizona," she said.

The clerks handle such tasks as filing invoices and billing notices, arranging dock visits by customs inspectors, and ensuring that cargo moves off the dock quickly and gets where it's supposed to go.

The increasing computerization of such tasks, which allows them to be performed in cities far from the ocean, makes the clerks especially vulnerable, say labor experts.

"These are fairly complicated jobs, you can't just hire anybody to do them, but nevertheless they can be done from other places," said Nelson Lichtenstein, director of the Center for the Study of Work Labor and Democracy at the University of California, Santa Barbara, said Wednesday.

Moving such jobs overseas or to states that pay less, and where unionization is not as strong, is something that has been a trend in the United States for decades, he said, giving as an example large company customer call centers that have been relocated to India.

"What's remarkable about this is that the union struck, they shut down the ports and they won," he said, adding it showed what the strong labor movement that still exists in the shipping industry is capable of accomplishing.

The clerks make average salaries of $41 an hour, or about $87,000 a year. They also receive pensions and several weeks of vacation a year. Their health insurance is fully paid and includes zero doctor co-pays, giving them among the best salary and benefits packages of any blue-collar workers.

The deal, reached late Tuesday night, must still be ratified by union membership, but both sides expect that to happen in the coming weeks.

Meanwhile, gates reopened at the ports and thousands of workers got busy unloading everything from cars to clothing, and television sets to computers from ships that had been idling in the ocean. Goods were placed on trains and trucks, to be delivered across the country.

"It's going to take a few days, maybe a week or two to get back to normal," said Long Beach port spokesman Art Wong.

During negotiations, shippers fought vigorously against the job guarantees, maintaining that would force them to keep people on the payroll that weren't needed.

Ultimately, they compromised to end the devastating strike that shut down 10 of the 14 terminals at the ports and cost the region billions of dollars.

"At the end of the day, it was important to reach compromise to get people back to work, and we agree the deal will extend growth at the ports," said Steve Getzug, a spokesman for the Los Angeles/Long Beach Harbor Employers Association, which represented the shipping companies.

In just a week, the strike had begun to create concerns there would be shortages of everything from retail merchandise needed for next month's post-holiday sales to repair parts for Redbox video kiosks.

Christmas merchandise had already arrived before the strike began.

During the walkout, officials estimated roughly $760 million worth of cargo a day failed to move through the ports. Twenty ships headed to other ports in California and Mexico, while some simply didn't sail from their home ports. Still others idled at sea.

Clerical workers walked out Nov. 27 after working without a contract for 30 months.

Although the strikers numbered only about 450, thousands of dockworkers represented by a sister union refused to cross the picket lines, stalling work at the complex that handles 44 percent of all container traffic that arrives in the U.S. by sea.

The new contract calls for a $1 an hour raise immediately and another $1 an hour bump next year, with raises in the contract's third and fourth years still to be determined. Employees will also receive $4,000 lump sum payments for the 30 months they worked without a contract.

Their pension benefits will increase slightly, and their vacation and health benefits will remain unchanged.

When their contract expires in 2016, Merrilees said, they should expect to face the outsourcing issue again.

"This problem is one that's rampant across the country," he said. "It's great that port workers were able to get this problem in these ports subject to more controls, but meanwhile the impacts of outsourcing are still being felt across the country."