Spain is responding to the steady increase in the arrivals of migrants from Africa to the Canary Islands. Local officials have started to pressure the Spanish government to transfer most of the migrants to the mainland. Spain will deport those migrants who do not fulfill the criteria for refugee status or employment in Europe.
So you have a group of people you allowed in your borders. Then they affect your custims and beliefs, your actual citizens dont want them there and instead of looking bad to the whole workd and sending them home. You instead send them to an island of yours that doesnt want them there either. Maybe you shouldn't have took that many in then. Just a thought.