Open ocean or on land for salmon farms

The Marlborough Recreational Fishers' Association and Soundfish say farming salmon in the ocean or on land would be more sustainable than in the Marlborough Sounds.

Retired biologist John Leader suggested this alternative at the Environmental Protection Authority hearing in Blenheim on Tuesday, in a submission from the fishing groups and Des Boyce, who sits on both groups' committees.

In its prospectus, the Nelson-based Cawthron Institute says its current focus is sustainable fish farming in the open ocean, Mr Leader said. Given this, it was surprising King Salmon, which employed Cawthron experts in its application to expand in the Marlborough Sounds, rejected ocean farming as technically impossible.

A mussel farm was planned for a deep-water site offshore from Pegasus Bay in Canterbury and consent had been granted for deep-water aquaculture on the west side of D'Urville Island in the Marlborough Sounds and in Clifford Bay near Ward, Mr Leader said.

Overseas, there were many deep-water fish farms, including one in Hawaii raising many tonnes of fish in submerged pens. This company was trialling new technology including remote monitoring that meant farms could be left unattended for two to three weeks in rough weather.

For King Salmon, disadvantages of deep sea farming would be more costly net construction, anchoring, travel and harvesting, Mr Leader said.

These would be offset by faster-growing, healthier fish and the marketing benefits of clean technology.

King Salmon aquaculture general manager Mark Preece had said land-based farming was feasible but operating costs were double those of the company's sea farms.

However, a Canadian study found it would cost $12 to $14 million to build a farm capable of growing 1000 tonnes of fish, he said.

This was similar to the cost of the hearing and would eliminate community concerns.

Clifford Bay near Ward would be a suitable place to build a land-based farm, Mr Leader said.

The Marlborough Express