Minecraft Spawner only creates fishermen?

I set up three spawners in a desert village that villagers spawn. Immediately afterwards, however, almost all of them turn into fishermen. How can I change that or what can be the reason?

The villagers get their jobs through different blocks. The fisherman e.g. Becomes a fisherman when a barrel is around. He then runs there and gets the job.

So you would have to place the spawners further away from the barrels, then they would no longer be allowed to take the job

Or you block the path to the barrels.