Native rock oysters grow prolifically along the Northland coast but are not farmed commercially in Aotearoa, despite a thriving rock oyster industry across the Tasman. Photo / Sean Handley
Native rock oysters grow prolifically along the Northland coast but are not farmed commercially in Aotearoa, despite a thriving rock oyster industry across the Tasman. Photo / Sean Handley
A Northland iwi and research organisation Niwa are investigating whether New Zealand's long defunct rock oyster industry can be brought back to life.
The native rock oyster — found in Aotearoa and across the Tasman, where it's known as the Sydney rock oyster — was the basis of a seafoodindustry in Whangaroa Harbour in 1960s.
It didn't last long, however, with Niwa marine biologist Sean Handley saying farmers switched to Pacific oysters because they were bigger, faster-growing and easier to raise.
''That led to the rock oyster largely being overlooked here for the past 50 years,'' he said.
However, a herpes virus devastated Pacific oysters in Whangaroa and the Bay of Islands about a decade ago.
The industry was recovering but work to breed Pacific oysters able to withstand the virus was ongoing.
The rock oyster, however, was not affected by the virus.
While rock oysters were smaller and more difficult to grow, in Australia they fetched a higher price than Pacific oysters because of their more intense flavour, Handley said.
Now Niwa scientists were working with Kahukuraariki Trust Board to determine whether Whangaroa's rock oyster industry could be revived using modern aquaculture techniques.
Trust general manager Geraldine Baker said the iwi's strong relationship with the marine environment, and a relatively recent history of subsistence from the whenua and the moana, meant it made sense to look to the sea to develop customary, commercial and employment opportunities.
Reviving the once-prosperous industry would pose challenges but it was looking fairly promising so far, she said.
Once the concept had been proven the next step would be to form partnerships with like-minded investors.
A renewed rock oyster industry could give iwi a chance to use their own water space and employ and develop their people, while attracting new investment to Tai Tokerau, Baker said.
Native rock oysters are smaller and slower growing but more flavoursome than Pacific oysters. Photo / Sean Handley
Handley said an attempt last summer to harvest oyster spat (larvae) from Whangaroa Harbour was unsuccessful.
Scientists then tried putting rock oysters in Niwa's Northland Marine Research Centre hatchery where they were conditioned for a few months before being spawned.
''The first spawning was very successful and produced more than one million eggs and larvae. From there you tend to get about a 30 to 40 per cent success settlement rate so we now have about 300,000 rock oyster spat.''
Settlement was a vital step in the lifecycle of the oyster and occurred when larvae attached themselves to a surface to grow.
From there the young shellfish were transferred to a ''flupsy'', which resembled a small barge with a paddle wheel.
The flupsy was fitted with trays covered in fine mesh allowing the shellfish to grow in open water while protecting them from predators until they were large enough to survive on their own. They also provided greater water flow enabling faster growth.
Handley said the spat needed to be 2-3mm long before they could go into the flupsy.
''We're in the early stages at the moment but this is about diversifying our existing oyster industry. Long term we'd like to establish breeding programmes so we can genetically select for good condition and marketable quality.''
Initially rock oysters were likely to be an iwi-led niche product but there was plenty of scope to complement the Pacific oyster market, he said.
Kahukuraariki Trust Board was formerly Ngātikahu ki Whangaroa Trust Board, set up to progress the small Far North iwi's Treaty claims. The settlement was passed by Parliament in 2017.
