https://web.archive.org/web/20180709153441/https://www150.statcan.gc.ca/n1/pub/89-001-x/2007001/4064952-eng.htm

Abdurrahman Aydemir, a Statistics Canada researcher, and George Borjas, Professor of Economics and Social Policy at the Kennedy School of Government of Harvard University, have found that a migration-induced shift of 10% in the supply of labour is associated with a 3% to 4% movement of wages in the opposite direction. International migration, in other words, raises a country’s wages whenever it decreases the size of its workforce; it lowers wages whenever the opposite is true.

Convoluted way of saying that immigration decreases wages. This is basic economics. Increased labor supply reduces bargaining power and thus average or median wages are reduced.

Even if a country needed a certain kind of labourer to address a shortage, an industry should first attempt for a specified time of recruiting locally and through increased wages as an incentive, and only after having done that should external sources of labor be pursued. Even then, there's no reason to give economic migrants citizenship or any form of political enfranchisement in their host country. Let them come work and then leave when their contract is done.