As a Lyttelton berth designed to fit the worlds biggest cruise ships nears completion, there's concern there's been long-term damage to the local Hectors dolphins.

Researchers are worried the noisy underwater piling has affected the dolphins' hearing and behaviour, and local residents are vowing to continue trying to hold Lyttelton Port Company accountable, after a year and a half lobbying against its work.

But the company says there's been no damage to the species, thanks to its "world-class" protection marine mammal management plan. Katie Todd reports.