Lice kill salmon
The New Zealand salmon farming industry is lucky to have no fish pests or diseases so no need to treat them with chemicals, says Scottish fish-farming expert Kenny Black.
Professor Black of the Scottish Association of Marine Sciences spoke to about 70 people at the Marlborough Convention Centre in Blenheim last night about the salmon farming industry in Scotland. he Marlborough District Council invited him to Marlborough to review monitoring results for salmon farms in the Marlborough Sounds and help write guidelines for the industry.
Professor Black said lice which infected farmed salmon and spread to wild populations were the Scottish industry's number one concern.
Before treatments were developed in the early 2000s, lice ate farmed salmon back to the bone, he said. They then died from disease which entered through the holes they left.
The problem was returning as lice became resistant to treatments, he said.
In Norway the government had ordered the cull of 8000 tonnes of affected salmon, still sold as food.
Last month recreational fishers in Scotland were calling for their government to take similar action.
The pacific salmon grown in New Zealand were resilient to lice but it was inevitable that a disease would eventually come along, as in any farming industry, Professor Black said.
Scotsman Angus Walton who has been living in Blenheim for three months said he supported the salmon industry but its profits should not be placed ahead of recreational fishing. Sports tourism was worth £280 million ($NZ 550) in his country.
Professor Black said he too loved fishing and was anxious to see the problem solved. A promising tool was a fish species which vacuumed lice off salmon and research was underway into breeding these.
As the over £400m Scottish industry evolved, 250 farms had concentrated in areas most suitable for farming, Professor Black said.
"A lot of early farms were in the wrong place and when they tried to expand went badly wrong, he said. "Sometimes a 100 tonne site was literally boiling."
Consolidation solved the problem as five large companies bought out then abandoned unsuitable sites.
The value of farmed fish to Scotland exceeded earnings from the commercial catch as well as beef and lamb, Professor Black said. Yet it had better green credentials on carbon footprint and energy efficiency.
Space in Scotland was increasingly constrained pushing cages out into areas with enormous waves peaking at 30 metres or the height of a 10 storey building.
"It remains to be seen whether cages will withstand the waves and whether fish will stay in their cages, '" he said
- The Marlborough Express