A weather event "not seen in a generation" has left New Zealand's North Island with severe flooding, widespread damage, more than 10,000 displaced and at least three dead.

Having declared its third-ever state of emergency, the country -- including its sizeable seafood companies -- is now trying to assess the damage.

"All our staff are OK," Tony Hazlett, CEO of fishing and processing giant Talley's, told IntraFish.

Cyclone Gabrielle's damage has been most extensive in coastal communities on the far north and east coast of New Zealand's North Island, where nearly a third of New Zealand's 5.1