The Port of Los Angeles on Tuesday reported lower container volumes in December compared with the previous year because of the weak global economy and a change by a shipping line.

The number of containers moving through the port declined 9.4 percent last month to 588,154 from 649,468 in December 2011. December imports fell 6.7 percent to 296,874 units compared with 318,355 the previous year. Exports declined 16 percent.

The port attributed last month’s lower volume to a weaker global trade environment in December. In addition, French shipping line CMA CGM Group moved a weekly ship call from Los Angeles to the neighboring Port of Long Beach, which hurt the L.A. numbers but will likely give Long Beach’s a year-end boost.

The Los Angeles port finished 2012 with volumes increased 1.7 percent compared with last year. The total number of containers was about 8.1 million, compared with 7.9 million in 2011.