The flow of immigrants into California has helped increase wages and job opportunities for US-born workers, according to a study released Tuesday that challenges the long-held belief that newcomers take away jobs from Americans. Immigrants do not compete directly with native workers for jobs, but tend to bring different skills to the workplace, said the Public Policy Institute of California report. This allows native workers with the same education level to take more specialized, better paying jobs. "The labor market is not a market of identical people," said University of California, Davis economics professor Giovanni Peri, the study's author. "Workers have different skills, perform different tasks, have different experiences, fill different positions." Advocates for greater curbs on immigration criticized the study, saying the arrival of immigrants can push US-born workers of similar age and education to other states, or out of the work force altogether. "There's no such thing as an immigrant-only occupation," said Steve Camarota of the Center for Immigration Studies. The PPIC study, titled "How Immigrants Affect California Employment and Wages," analyzed 40 years of Census data and the 2004 American Community Survey, a national survey by the US Census Bureau.