Gilbert the Hero by Jane Clarke
It's great fun having a new baby brother, right? Well, not for Gilbert the Great White Shark. His new baby brother, Finn, is too small to join in with any games and is no fun at all. So when Gilbert's friend Mallett suggests a game of skating, Gilbert decides to leave Finn alone and join in. But what a mistake! Soon an enormous orca appears and it has Finn in its sight. Can Gilbert reach Finn in time to save him from the jaws of the orca. An exciting third book in the Gilbert series where Gilbert discovers that being a big brother can sometimes be fun after all.