Ask John Minaur to tell you the difference between farmed and wild salmon and his face goes blank for a moment, rather as if you had asked a prize pig farmer if he knew the difference between a pork chop and wild boar. Chairman of the Scottish Salmon Growers Association, he has a thriving marine salmon farm on Lake Carron, a huge sea loch indenting into the coastline opposite Skye.
The wooden frames of the cages, or "sea-pens", which holds the nylon notes, form an unobtrusive line in the loch waters. Each pen surrounds about 250 cubic metres of sea water, 15 metres deep, and is home to 4,000 to 5,000 salmon - exceed this and you will get sick fish and no insurance cover. On shore a small, low white building houses feedstores and small offices. As you approach the pens by boat, gleaming silver smolts, young salmon which have passed the river phase to live and feed in salt water, leap out of the loch.
The fish are fed at regular intervals with small pellets travelling down hoppers sitting on each pen - if irregularly fed, salmon are prone to eat each other. These pellets are composed of cooked, dried fish-meal, with oils, vitamins and amino acids, lost through heating, replaced. Salmon consume fish in the wild, but it is the shellfish in their diet which give the characteristic pink flesh. In farming, the colouring agent in crustacea is synthesised chemically and added to the feed at specified levels approved by the Food Advisory Committee.
It has taken more than 20 years of observation, trial and error to turn salmon from wild fish into farmed animals. Now, the whole delicate cycle from egg to full-grown salmon is a highly controlled operation. One "hen" lays about 3,500 eggs in the river and of these only two need to become adult fish for the population to remain stable.
In a fish-farm there will be a survival rate of about 98 per cent after the eggs are fertilised until hatching. Once the young salmon are smolts in sea water, about 85 per cent will live, as opposed to 2 per cent in the wild. Salmon mortality is extremely high. The North Atlantic Salmon Conservation Organisation is concerned about stock depletion - taking into account the reduction in tonnages of caught fish, an average 11,000 tons of salmon was landed in the 1960s, under 7,000 tons in 1984. The reduction stems from a combination of overfishing and pollution. It is in the interests of the fish farmer to care for his animals. At a fish hatchery at Invergarrie, the daily log carries as many details as a hospital patient report. "Fish appear comfortable," one observer wrote, but added underneath in pencil: "I am stressed."
How can you tell an unhappy salmon? Everyone involved in farming seemed to agree: an unhappy fish is a sick fish. And down on the farm sick animals dent the profit margin. But not everyone in Scotland is sanguine about the salmon industry: there is a snobbish premium attached to wild fish and objections have been raised to the quality of farmed fish. Some small farms with limited financial backing have been accused of overcrowding lochs and producing poor-quality salmon. But on good farms, where salmon are given sufficient exercise, being placed in currents, or even towed in cages to swim against them, there is no reason for the flesh to be fatty or flabby. Most salmon experts agree that given a prime-quality farmed fish and a wild one, once cooked no-one could tell the difference.
For fish campaigners, however, healthy salmon and a booming industry are not the end of the story. Friends of the Earth would like to see more control, with all site licences to be covered by local authority planning permission, instead of the Crown Estates Commission, as at present. It also wants husbandry standards to be monitored by the Department of Agriculture and Fisheries, instead of the present self regulation.
The main anxiety is the fear of what might happen when the market reaches saturation point, which is not far off. Friends of the Earth is concerned about the effect on employment if big fish-farm owners such as Marine Harvest (Unilever) and Booker McConnell pull out of Scotland to find more profitable operations elsewhere.
A handful of men working for the future think they may have the answer. On the western Highland coast is the isolated Marine Farming Unit of the Sea Fish Authority at Ardtoe. In 1983 Peter Smith and John Dye obtained 19 live, mature halibut from a trawler. This year, after trials with 1.8m eggs, they hit the headlines in the fish world. Six young halibut are now swimming around a tank, proof that this highly prized pricey fish could one day be farmed and supported by our cold waters. If farmers succeed in taming this reclusive fish, it could be the saviour of the Scottish fishing industry. And Smith and Dye, who have cooked and tasted both wild and farmed halibut, say you cannot tell the difference.
