RESIDUES of an illegal, highly toxic fungicide formerly used to clean fish farm cages are still being detected in salmon on sale to the public in Scotland, according to tests carried out by a government agency.
Malachite green is a carcinogenic agent that was banned by the Scottish Executive in June last year following discussions between the UK and the European Commission.
The chemical is a synthetic fabric dye but was used by the industry because it kills parasites on the sea cage pens in which the fish are farmed.
Suspected of causing genetic mutations that can lead to malignant tumours in humans, it has now been replaced by an alternative, pyceze, developed in the UK with the assistance of funding from the salmon and trout industries and the Department for the Environment, Food and Rural Affairs ().
Analysis for malachite green, and the residual compound leuchomalachite green, in Scottish farmed salmon only began in 2001, and is carried out on a quarterly basis by the Veterinary Medicines Directorate, an agency of . Previously unpublished results obtained by The Scotsman show that detection of the harmful chemical has remained reasonably steady since the tests began despite the ban.
In 2001, six out of 30 samples of farmed Scottish salmon, about 20 per cent, were found to contain the fungicide. The following year, the detection rate fell slightly to eight out of 52 samples, about 15 per cent.
But in the first quarter of this year, 14 out of 74 samples analysed have tested positive for leuchomalachite green.
It is not clear which company is responsible for the production of the contaminated fish or from which retailer the samples were obtained, but the industry body Scottish Quality Salmon, which represents 65 per cent of the salmon produced in Scotland, maintains that none of its members has used the fungicide since it was banned.
One expert at the directorate claimed that the statutory surveillance programme for farmed fish is targeted, to increase the chances of detecting the use of malachite green, and maintained that the figure 19 per cent is not therefore necessarily representative of the overall picture.
He added that few in the salmon industry would be surprised if the next quarterly report, due any day now, revealed several more instances of detection.
"Although the use of malachite green was banned in the UK last year, estimates indicate that we can expect to see residues up to around June 2006, and possibly for longer.
"This would not prove or suggest that there has been any use of the product in the UK since the ban was introduced."
Early last month, a consignment of Chilean farmed salmon was impounded in Rotterdam by the Dutch authorities due to high levels of contamination with leuchomalachite green.
Chile banned the use of the fungicide, which is 20 times cheaper than modern alternatives, in 1995 but environmental groups in the South American country suspect aquaculture companies are continuing to use it to cut down costs.
Marine Harvest Chile - a subsidiary of Nutreco, which is also the biggest farmed salmon producer in Scotland - has been implicated by Chilean environmental groups in continuing use of the chemical. There is no suggestion that it continues to use malachite green in the production of Scottish salmon. A spokesman for SQS said it is mandatory for member companies to produce salmon under its strict, quality assured, independently inspected product certification schemes.
He added that SQS acknowledged the concern about the historical use of malachite green and had made a massive financial investment to expand its residue-testing regime. This included a set of robust testing procedures it says are over and above the statutory surveillance undertaken by the directorate.
Brian Simpson, the chief executive of SQS, added: "Consumers rightly expect exceptional quality, which is exactly what they get from members of Scottish Quality Salmon."
Dr Richard Dixon, the head of research at WWF Scotland, said the residues were likely from the chemical being used legally before it was banned.
However, he added: "It will rightly concern the consumer that a chemical that has been banned for human health reasons, even if the industry is 100 per cent observing that ban, is still in fish that they may buy.
"It could have been avoided by the industry if they were much more forward thinking and enlightened in their attitude," Dr Dixon said.
Aim to export meat-free oysters
A SCOTS fish farm is experimenting with ways of mass producing seaweed and has predicted that the "vegetarian oyster" could be the next big thing in the seafood industry.
Loch Duart, a salmon farming company based in remote Scourie in Sutherland, is looking at how it can produce enough seaweed to export it to restaurants across Europe and Japan.
Despite its rubbery appearance, the plant is said to be very similar in taste to the oyster.
According to the managing director of the farm, Nick Joy, seaweed is packed with vitamins and minerals and could help replace nutrients which salmon farming takes out of deep sea lochs.
"It has a very sea-y taste, a bit like an oyster," he said.
"It’s a very exciting idea because seaweed is very good for you, very nice to eat and can be eaten by vegetarians too."
The company’s sustainably-farmed salmon is served in top London restaurants.
Now Mr Joy is hoping that the farm can start expanding seaweed production to around 200 tonnes annually within the next four years so that it can start exporting.
He said demand for seafood is high at the moment, largely because of the boom in popularity of sushi across Europe.
But he warned that plans to mass produce seaweed, which is grown on ropes, are still "very much at an early stage" because of the difficulty of cultivating it in bulk.
"We know it grows, the question is how to get the best quality and the right volume," he said.
"I tasted some from our ropes last week and it wasn’t as good as the stuff in the spring. It took a long time to learn how to farm salmon properly and sustainably and it’s going to take a long time for seaweed as well."
Seaweed has been an important part of the Japanese diet for more than 2,000 years and was used as herbal medicine by the Greeks and Romans.
It is used in Wales to make lava bread - small cakes baked with oatmeal.