A Tauranga mussel processor has opened a new facility which will give it the largest half-shell production capacity in the world.

The NZD23-million (US$16.24-million) facility at North Island Mussel Processors Ltd (NIMPL) was opened Thursday (Jun 17) by Prime Minister John Key.

NIMPL director Peter Vitasovich said the new facility featured New Zealand-designed automated mussel opening machines, a world first which would increase export manufacturing capacity nearly three-fold.

Each of the 28 new machines would process up to 3600 mussels an hour, more than 1.6 million mussels in a 16-hour day.

NIMPL is a joint venture equally owned by exporters Sanford, Greenshell New Zealand and Sealord.

Chairman Geoff Burgess said the company's ability to process high volumes at a lower cost base would increase New Zealand's competitiveness in overseas markets.

The New Zealand greenshell mussel is larger than its European black shell counterpart and contains higher ratios of meat, protein and Omega 3.

Greenshell mussels represent nearly 80% of the NZD300-million (US$211.69-million) aquaculture industry, which in turn accounts for a fifth of the value of New Zealand's fishery production. The aquaculture sector has plans to become a sustainable billion dollar industry by 2025.

The giant Sealord company, which generated revenue of NZD584 million (US$412.1 million) last year, is owned jointly by Japanese firm Nissui and Maori-owned Aotearoa Fisheries, while Greenshell NZ is owned by Peter Vitasovich, the current chair of Aquaculture NZ.