Harrington Sound.

Aquarium curator Jack Ward said fishing lines have been set in the hope of catching what could be a nurse shark.

The search started last week after reports from a member of the public that a shark was in the Sound. Nothing could be found but Aquarium staff decided to try to hook the fish, if it existed, alive.

A nurse shark has never before been spotted in Harrington Sound and officials are sceptical that the reported sighting has any credibility.

But they would still like to add a nurse shark -- which feeds on the bottom, grows to eight feet in length and is not dangerous to humans -- to the collection.