Blueback by Tim Winton: Blueback as a FABLE?

Blueback when it was first published had a sub title - 'A Contemporary Fable'

Why might the book be seen as a fable?

The World Book Dictionary gives four definitions for the word fable. they are:

1. A story or tale made up to teach a lesson. Fables are often about animals who can talk as in The Hare and the Tortoise. (See video below)
2.  An untrue story; fabrication; falsehood.
3.  Myth; legend: Greek fable.
4. The plot of a drama or epic poem.

Blueback is definitely a book that contains a message but is its aim to teach a lesson?

Perhaps the novel fits into one of the other definitions of a fable. What do you think?

Source of info: Teacher's notes, Dr. Susan La Marca