Mussel exports to China have been boosted by an agreement with a leading player in the market.

Shandong Oriental Ocean Group has agreed to stock its new chain of premium seafood stores opening in China with New Zealand greenshell mussels.

A delegation from Opotiki in the Eastern Bay of Plenty - which has resource consent to set up the country's biggest mussel farm - negotiated the deal during a trip to China last month.

Oriental Ocean is based in Yantai, Tauranga's sister city, and the firm's president, Professor Che Shi, will visit the region in September to sign the deal.

Che is also vice-president of China's aquaculture industry group, and his company plans to open 500 stores throughout China over three years.

Che has indicated the deal could eventually amount to 20,000 tonnes a year - almost two-thirds of our mussel exports in 2008, $204.25 million for 33,300 tonnes.

About 11,000 tonnes went to the United States in 2008, which was by far the biggest export market for greenshell mussels.

New Zealand Greenshell, which farms in the Coromandel, will supply Oriental Ocean, with Opotiki's Eastern Seafarms coming on board once its production is established.

New Zealand Greenshell managing director Peter Vitasovich said the 20,000-tonne figure was far from concrete, but a first shipment to Oriental Oceans was expected once the new mussel season began in October.

A group of firms - Aotearoa Seafood, New Zealand Greenshell, Pacifica Seafood and Sanford - have also set up an office in China to market under the name New Zealand Pure Greenshell Mussels.

Opotiki's Eastern Seafarms, which will drop 5km of its first mussel lines next month, reportedly has a target of $250 million turnover within 15 years and is expected to create 900 jobs in the impoverished district.

The 3800ha farm has been set up as a joint venture between Opotiki's iwi, Whakatohea, and Sealord.

The district's aquaculture will eventually expand into fin fish, scallops and oysters.

Opotiki's delegation also negotiated with Oriental Ocean to receive expertise and direct cash investment for a sea cucumber farm.

Ponds will be dug onshore to harvest what is an expensive delicacy in China, with the first commercial trials on 2ha to begin within six months.

The New Zealand sea cucumber is regarded as virtually indistinguishable from the species harvested in China for medicinal properties.

Eastern Seafarms director Ian Craig said the district had built up an almost exclusive relationship with the Chinese giant over years of meetings.

Opotiki Mayor John Forbes said the town's relationship with Oriental Ocean was a special one and would serve it well into the future.

"In China, you don't walk in and drop a business proposal on the table. You do a lot of relationship building, and if they decide you're appropriate, then later on you can start to discuss proposals," he said.

"They've taken quite a shine to our Maori leadership and hold them in high esteem."