Big new stocks of lucrative export fish have been found in New Zealand's exclusive economic zone.

But snapper stocks around the northeast North Island - including Auckland - are worse than expected.

The Ministry of Primary Industry published the new data in its latest Fisheries Assessment Plenary which summarises fishery, biological, stock assessment and stock status information for 82 of New Zealand's commercial fish species or species groups.

New Zealand fish exports are worth about $1.5 billion.

Principal fisheries science adviser Pamela Mace said snapper was faring worse than expected.

"There appears to have been a general increase over the past 10-20 years, but preliminary results this year indicate that further [stock] rebuilding is still needed," she said.

The Ministry is commissioning further investigation.

South Island north coast paua is also in need of rebuilding, Mace said.

The assessment reports a new discovery of orange roughy near the Chatham Islands and historically high stocks of southern blue whiting in the Campbell Island region.

Southern blue whiting is a factory fish that can be filleted easily and fries, bakes, microwaves or steams. Its mild flavour is highly regarded as it neither particularly smells, nor tastes, like fish.

Worth around $22 million a year, it makes fish cakes and balls, including a high quality surimi - the Japanese word for "ground fish meal" or karaoke.

Orange roughy, one of New Zealand's more lucrative catches, had been under stress due to over-fishing in the '80s and '90s. New Zealand exports around $51 million a year in orange roughy, mainly to the United States.

The report shows that eastern and western stocks of hoki have continued to increase in size over the past six consecutive years, and both are now well within their target range.

Gurnard around the east and south coast of the South Island was reported as to be very likely above its management target.

A trawl survey estimate for John Dory off the west coast of the South Island was at the highest recorded since 1992.

Elephantfish populations around the east coast of the South Island appeared to have fully rebuilt, and around the south coast of the South Island they have been continually increasing since the mid-1990s.

- © Fairfax NZ News