The Stewart Island paua fishery is in such good heart, the Ministry for Primary Industries stock assessment pointed to a possible catch increase.

 The harvest (Total Allowable Commercial Catch) is just 90 tonnes, the minimum harvest size observed by professional divers  has been boosted to 137mm, as against 125mm in the recreational fishery there and in most of the rest of the country, and the fishery is assessed at being at 44 percent of its original biomass.

  The fisheries management target is 40 percent, well above the maximum sustainable yield.

  The area, designated PAU5B, is a prime example of good fisheries management, MPI principal scientist Julie Hills told the Paua Industry Council conference in Nelson last week.

  Despite all these favourable factors, quota holders plumped for caution and asked MPI not to consider moving the catch upwards just yet.

That conservative approach is echoed through the country, where quota holders, far from pushing a lucrative catch to the limit, have voluntarily shelved large quantities in the interests of enhancing the health of paua fisheries.

  Julie Hills (Jules) – surfer, diver and former high country musterer on horseback – is chair of the Shellfish Working Group and oversaw the Paua Fishery Research programme 2016-21.

She has developed stock assessments based on mathematical models incorporating biomass, fisheries dependent performance indicators such as catch per unit effort (CPUE) and other measures like shell length frequency and age at maturity.

“But if the divers say they don’t agree with the results, then there’s something wrong with your model,” she told the 70 Australasian conference delegates.

Her assessment was PAU2 (from North Cape south and around to Taranaki) was an amazing, stable fishery for many years, one of the country’s most productive.

PAU3 along the Kaikoura coastline had been looking good and the CPUE had been steady for many years. The quota has been halved to 45 tonnes by closure since the Kaikoura earthquake and there is concern about the recreational take displaced to adjoining open areas and poaching.

  PAU4 (Chatham Islands) has never had a stock assessment and has a TACC of 326 tonnes, one third of the total national catch. Despite having the country’s best catch rate and very low recreational and poaching pressure, a 20 percent shelving is in place and that may be increased further to 30-40 percent, with some parts of the fishery showing some signs of stress according to divers and what research is available.

  PAU5A in Fiordland is healthy, with the southern area at 41 percent of original biomass and the northern area at 47 percent. Even so, a 30 percent shelving remains in place after eight years, with 104 tonnes of a 149 tonne TACC caught.

PAU5D on the south east Otago coast also has a 30 percent shelving in place, with a TACC of 89 tonnes. Biomass is estimated at 35 percent of the original, the fishing area has been compressed with the addition of three mataitai and a Taiapure and there is strong recreational and illegal pressure.

PAU7 at the top of the South Island across the Marlborough Sounds was down to just 18 percent of the original biomass and the TACC was halved in 2016 to 93 tonnes, with a further 10 percent shelved since the earthquake.

PIC chief executive Jeremy Cooper said the paua fishery was at the bottom of its cycle and predicted the harvest would rise by about 20 percent to 857 tonnes in the next 10 years and there would also be an emerging market of about 8 tonnes for yellowfoot paua.

MPI deputy director-general regulation and assurance Brian Wilson told the conference the paua industry has a reputation for good governance structures and has shown leadership in responsible fishing.

  “You have also led innovation in terms of initiatives like catch spreading, minimum harvest sizes, the use of electronic reporting and continuing active involvement in all aspects of paua science,” he said.

  “Longer term MPI Future of Fisheries work will focus on fine-scale management, what decisions can be shifted or delegated downwards, and how this should be done.”

  Authorised management, where quota owners were given the tools to act collectively to better manage their own harvesting rules, fishing efforts and behaviour, was being considered in the mix.