However, when it happens, it will create jobs six kilometres off the tip of D'Urville Island on the western edge of Cook Strait for a small and hardy crew, who will spend days at a time on a glorified houseboat attached to a very large net full of salmon.
A second such net, capable of being submerged during bad weather to stop wave action from either damaging or losing fish, is planned another six kilometres away.
When a storm comes in from the northwest, the crew will be evacuated. For the rest of the time, they'll be out there on their own.
Rosewarne's announcement was significant in part because it coincided with an inaugural New Zealand symposium on open ocean aquaculture, organised by the country's leading independent marine science entity, the Nelson-based Cawthron Institute.
Its chief executive, Dr Charles Eason, sees massive potential in harnessing New Zealand's open ocean resource not only for finfish, but for shellfish and seaweed production.
The opportunity comes from a combination of: environmental pressures curtailing land-based agricultural protein production; growing world food demand; and the expanding potential for "precision aquaculture" using big data and digital technology to feed, care for and harvest fish.
The goal is to do so at a cost, environmental impact and volume that could make aquaculture as big a contributor to the New Zealand economy as pastoral farming, maybe bigger, with far lower environmental effects.
Eason is spurred in part by the fact that New Zealand aquaculture has been developing increasingly deep links with other countries exhibiting similar potential.
Norway leads the charge, investing in open ocean technologies on a scale unimaginable to most countries, using its North Sea oil and gas riches to build replacement industries for a low-carbon world.
Piggy-backing the Norwegian effort is an efficient way for New Zealand to climb a learning curve that is not only steep, but where much is still not known.
This week's symposium saw presentations on a bewildering array of potential technologies. Some look like upended submarines moored to the ocean floor, others like oil rigs. The most intriguing is the Nordlaks Havfarm, a purpose-built ship with no bottom and fish pens instead of cargo.
Being mobile, it could move away from bad weather and minimise the environmental impact of a fish-farm that's tethered in one place.
It looks an extremely expensive way to farm fish. However, the firm began advertising for 11 people to crew the prototype just last month.
The King Salmon proposal is much simpler. It will use proven submersible fish cage technology capable of holding somewhere between 4,000 and 5,000 tonnes of salmon – roughly half the total production now achieved from the company's Marlborough Sounds operations.
Its move into the open ocean has three motivations.
Firstly, King Salmon has struggled to gain necessary community acceptance in the Sounds. That's despite being a major employer and having a minimal environmental impact compared with land-based farming to produce the same amount of animal protein.
It hopes that by moving well offshore, concerns about both its aesthetic and environmental impacts will all but disappear.
Secondly, moving offshore will massively increase its potential total production. It produces a high margin product now that cannot meet current local and export demand.
And thirdly, the Sounds are becoming too warm for salmon.
Associate Professor Moninya Roughan, who leads the MetService's MetOcean division, told the Cawthron symposium that the Tasman Sea is warming four times faster than global averages.
"New Zealand and Australia are the only countries that breed salmon in a hotspot of global warming," she warned.
King Salmon has lost above average numbers of salmon owing to high water temperatures over the last two summers and can expect this to be an ongoing problem.
The implication for the firm's survival and growth is clear: a managed retreat into larger farms, further from shore, positioned on the South Island's east coast – away from warming Tasman waters and benefitting from currents pushing up from Antarctica.
If this sounds like the job for you: form a queue.
