There are fears that silver carp will squeeze out smaller indigenous species such as pike, bream and barbel, and be impossible to control.

Other experts point out that that redwoods are a 'polite' species, slow to reproduce without human help and unlikely to overpower indigenous species.

Whitebait fishermen were keen that these fry were known as a specific indigenous species.

Indigenous species are at risk from population decline or extinction if any invasive species are introduced.

At that time, there were 10 cages containing 127 animals, mainly indigenous species.