No correlation exists between a high percentage of foreign-born PhDs working in a field and a high unemployment rate within that field. Engineering and computer science have the highest concentration of foreign-born in any PhD field, yet have unemployment rates of only 1.7 percent and 1.0 percent. Geosciences and the social sciences have a low percentage of foreign-born PhDs, and the unemployment rates in those fields are 2.2 percent and 2.8 percent respectively. Even more significant is what analyzing unpublished data obtained from the National Academy of Sciences and National Science Foundation reveals. The data measures people who completed their degrees in the same year, which is crucial, since, all things being equal, an individual 15 years in the field will earn more than someone relatively new.
Wages are a function of productivity.
We can only conclude then from the data that the foreign-born who work in America are exceptionally productive. Research and development would fly offshore if immigration restrictions prevented high tech companies from hiring the people who contribute to America's next generation of products and innovations. Undoubtedly, but there is no evidence this iswidespread in the science and engineering fields. You cannot pay foreign-born engineers less. These are smart people, if you try to fool with them, then they will go someplace else.