European slave trading became a major issue in what colony?

For the bolumen of slaves and the mistreatment they suffered, we can affirm that the Portuguese colony of Brazil was the one that had the most problems, even continue today.

Slavery, also known as slavery, was the form of social relation of production adopted, in a general way, in Brazil from the colonial period until shortly before the end of the Empire. Slavery in Brazil was marked mainly by the exploitation of the labor of blacks brought from Africa and transformed into slaves in Brazil by the European colonizers of the country.

The institution of slavery in Brazil takes shape with the large property in monoculture, in the 1530s. Portugal had just over 2 million inhabitants at the time and could hardly bear the loss of labor for expeditions to the East, which were in their peak. And, as for any other European settler, it was not interesting for the Portuguese to migrate to the tropics to be a simple country worker. "Slavery became, thus, a necessity: the problem and the solution were identical in all the tropical and subtropical colonies of America, in the English, where other forms of work were tried, in principle, a semi-slavery of white workers, the indentured servants, the replacement by black did not take long. "