They do not however expell (spawn) fertilized eggs they are fertilized after leaving the female AFAIK.
In an aquaculture course I took I raised them. I injected them with a chemical that induced spawning. Anyways the eggs and sperm were released into the water. Im sure that all species aren't the same, but this was 1st hand experience. The babies were about the size of a pencil eraser when they looked like the adults. This is why I thought they could be hitch hikers.