The colomber pursued him because he wanted to give him a pearl from the sea. It is believed that this pearl gives the bearer good luck, which is opposite of what the sailors were saying as they were claiming that someone on the ship was doomed and that it was bad luck.
In "The Colomber" by Dino Buzzati, Stefano Roi sees "the colomber," a fish that, according to his father, with haunt him his whole life and could only be seen by him and his family.
Stefano is sent to an inland school by his father to avoid the threat of the fish. After his father dies, he becomes a great sailor and succedes in avoiding the fish for fifty years.
When he is old, he decides that he wants to meet the fish face to face so he takes a small boat and finally encounters the animal. However, the colomber explains that he never meant any harm to Stefano and gives him a pearl that is supposed to bring good luck to his bearer.
