China has become by far the world's biggest abalone/paua producer through massive subsidised investment in the fishery.

The annual harvest, all farmed, has rapidly risen to 140,000 tonnes, about 85 percent of the world's total production.

New Zealand's share is minuscule at around 700 tonnes but it is largely wild caught and commands a premium, returning about $60 million in annual export earnings.

China barges in seaweed to feed the abalone, often from hundreds of kilometres away, and if the water becomes too warm, whole farms are uplifted and moved north on a special vessel, the biennial Australasian Abalone Convention in Hobart was told earlier this week.

Australia's production is about four times that of New Zealand at 2900 tonnes, both farmed and harvested across thousands of kilometres of coastline across five states - WA, SA, Victoria, NSW and Tasmania.

New Zealand's sole paua farm is the Moana-owned Oceanz Blue at Bream Bay in Northland, which produces about 50 tonnes of "cocktail" sized fish.

This country has taken a conservative approach to managing the paua fishery across eight commercial areas, with voluntary shelving of catch where it was thought stocks were under pressure, Paua Industry Council (PIC) chief executive Jeremy Cooper told the 115 delegates.

Peak paua was nearly 30 years ago with landings of 2000 tonnes. The industry has stabilised around current levels and is slowly rebuilding.

"We know that each of our fisheries can produce more and stay healthy if we implement good management," PIC chair Stormalong Stanley told the conference.

However, there are significant challenges, including ocean acidification, warming waters, sedimentation and loss of habitat.

PIC science officer Dr Tom McCowan detailed the monitoring of paua stocks following the 2016 Kaikoura earthquake and the development of a fisheries plan for a future, limited re-opening.

There are also regulatory demands, with every diver required to automatically download all catch, effort and location data on a daily basis to Fisheries NZ from October 1.

Cooper detailed the huge investment - along with some kiwi ingenuity - the industry has made over more than a decade to capture harvest data.

"At one stage we were the biggest purchasers of non-lubricated condoms in New Zealand," he said, explaining they were used to keep data loggers watertight that were worn by divers.

Cawthron Institute physiology team leader Dr Norman Ragg, known for quirky presentations, said he represented the voice of abalone - "a small, fragile animal that supports our livelihoods".

He said a marine heat wave in the 2017/18 summer had raised surface sea temperatures by 3.7 degrees C, unparalleled in 150 years of records.

The impact of heat lowering oxygen content and water movement on an individual paua, which he named Brian, could affect mucous production needed for crawling, fixing to rocks, waste removal and food availability.

Remedies could include kelp habitat restoration, careful reseeding and relocation and minimising additional metabolic burdens caused by sedimentation, pollution and coastal acidification.

Fisheries NZ senior fisheries analyst Mark Geytenbeek added to the Kiwi contribution to the conference, analysing the different Chinese and Japanese approaches to aquaculture and enhancement of abalone stocks following a study tour last year.