I'd need to see concrete numbers showing the reason behind those 30-40% unemployed was immigration, rather than other reasons.

When an immigrant moves into a country he contributes plenty to the local economy. He needs a haircut, so he goes to the local hairdresser. He needs groceries, so he goes to the local shop. He pays rent, buys a car, furniture, pays taxes, schools, etc etc. This helps a lot of people stay employed.

Economic crises happen. Industries - like paper and many others - simply become obsolete and some are going to die. If you are trivially replaced, or only qualified to work on a dying industry you're in for a tough time, and no amount of immigrant bans or protectionist policies is going to help you.