Seventeen skippers behind one of Scotland's biggest fishing scams have been fined a total of £720,000.
The group admitted making illegal landings of mackerel and herring worth £47.5 million between January 1 2002 and March 19 2005.
The "black fish" scam, which broke sea fishing laws, was carried out at fish processing factory Shetland Catch in Lerwick, Shetland.
Judge Lord Turnbull said the scam is "an episode of shame" for the pelagic fishing industry.
He said it was a "cynical and sophisticated" operation which had the "connivance of a number of different interested parties".
Hamish Slater, 53, and Alexander Masson, 66, both from Fraserburgh, were fined a respective £80,000 and £50,000, while Alexander Wiseman, 60, from Banff, was also fined £50,000.
Another 13 men from Shetland were fined for their role in the scam.
Robert Polson, 48, was fined £70,000; John Irvine, 68, was fined £80,000; William Williamson, 65, was fined £45,000; Laurence Irvine, 66, was fined £80,000; and David Hutchison, 66, was fined £40,000, as was 56-year-old Thomas Eunson.
Both Allister Irvine, 63, and Gary Williamson, 52, were fined £35,000; and George Henry, 60, was fined £12,000.
John Stewart, 57, was ordered to pay £15,000, while George Anderson, 56, must pay £12,000.
Colin Leask, 39, and Allen Anderson, 55, were each fined £3,000
A £70,000 fine was imposed on Victor Buchini, 51, from Poulton-le-Fylde in Lancashire.
The company Alexander Buchan was fined £240,000 for helping the vessel masters land the undeclared fish.
The pelagic fishermen, who committed the offences to evade the annual EU fishing quota, had already been ordered to hand over almost £3 million in confiscation orders at a previous court hearing.
The convictions came as the result of a seven-year investigation, Operation Trawler, after the Scottish Fisheries Protection Agency (SFPA), now Marine Scotland, became suspicious about widespread illegal landing of fish within the pelagic fleet.
Pelagic fish are those which swim near the water's surface.
Auditors KPMG reviewed Shetland Catch and found that between January 1 2002 and March 28 2004, the company's earnings were not supported by its declared landings.
The company premises were searched on September 27 2005 and officials found that scales used to weigh fish coming into the factory had been manipulated to provide false weights.
Management were able to input fake wastage figures into a computer in the main factory, accessible to inspectors from the SFPA, which would be deducted from the actual weight shown on the screen.
The proper weight was displayed on screens in the engineer's room and in a loft area, both of which were off-limits to SFPA officials.
The computer in the loft area was where the weight manipulation took place. It could be accessed remotely by two members of staff, a fish buyer and the then assisting managing director, using a username and password, allowing them to program it to provide false weights.
Lord Turnbull said the proceedings brought "embarrassment and shame" to the skippers and their families.
He said: "All of the accused who appear today have spent their working lives as productive and hard-working members of our community. Barring other regulatory infringements, not a single one has ever come into any conflict with the law.
"It was not surprising therefore to hear of the well-respected positions within their communities which many held and of the embarrassment and shame which these proceedings have brought to them personally and to their families."
The judge said the fishing industry "makes a crucial contribution" to the well-being of many communities and to the economy of the country as a whole.
He added: "There would of course be no fishing industry were it not for the willingness of fishermen to go to sea. It is correct to acknowledge that in doing so,fishermen require to cope with challenging circumstances of isolation from family members and often with dangerous and frightening weather conditions, the likes of which will be wholly unfamiliar to others with more conventional working environments.
"Over the history of the fishing industry and even in recent times in Scotland, tragedy has often visited the families of those who spend their working lives at sea."
The judge also noted that each master involved "made no attempt" to disguise their true income from the fish and paid income tax on both the declared and undeclared landings.
But he said the men had all participated in "a deliberate and calculated determination to evade the quota levels for fishing available to each vessel" for "purely financial" reasons.
He said: "The system through which this was achieved was both cynical and sophisticated and involved the connivance of a number of different interested parties, some of whom have benefited but have not been prosecuted.
"The extent to which landings of fish were deliberately under-declared was at times truly staggering and in the case of some of the accused concerned, took place continuously over a three-year period.
"What I found to be noteworthy was that no understandable explanation was provided on behalf of any the vessel masters as to why this practice was commenced or continued with.
"No one for example appears to have engaged in this exercise on account of struggling to cope financially with the costs of continued fishing within the quota levels allocated.
"Indeed, in contrast to some within the fishing industry, those engaged in fishing with the pelagic fleet appear to have been able to make very substantial sums over many years, providing very comfortable livings for themselves and their families.
"In short then, and as was conceded by at least some of those who appeared before me, the motivation for the sustained furnishing of false information was purely financial. Those who were already making a good living saw this as a way in which more income could be generated.
"No doubt the fact that so many were involved lent a veneer of acceptability to the conduct but there is another side to that as well: the fact that so many were prepared to participate in deliberate lies and falsehood means that the desire for financial benefit was able to overshadow the instincts of fairness, truthfulness and responsibility which will have influenced every other aspect of the lives of those concerned and which values they would expect to see others, including their own family members, abide by.
"The result is an episode of shame for much of the whole pelagic fishing industry.
"I have however accepted in each case that these proceedings have been responded to responsibly and that those concerned regret their involvement and the embarrassment which has been brought to them personally and to their families."
The men had previously been subjected to a reduced quota of fish to "balance out" the environmental effect of years of overfishing. But the judge insisted that this was not a punishment but an "exercise in conservation".
He said: "I do not accept that the accused in this case have lost out or have been made worse off as a consequence of these arrangements. I accept as accurate the observation that looking back with hindsight had they never over-fished at all then they would have achieved a greater income over the extended period than they in fact have.
"That is due to the massive increase in the prices obtained for the type of fish with which I am concerned in the period since 2002. That however is no more than an irony of the situation. It does not reflect any actual loss to those concerned. In fact, as a consequence of the increased value of the fish, those involved have still been able to generate very substantial incomes, despite being restricted to catching a smaller quantity.
"If the current prices remain stable then when the quota deduction arrangements have been exhausted, they will be in a position to increase that income even further."
He also referred to "activities of foreign fishing vessels" in exceeding fishing quotas.
The judge said: "If there is an imbalance in the approach of the relevant authorities within the European Union, that is a matter for the relevant ministers to raise with their counterparts.
"If vessels belonging to states outwith the European Union are thought to enjoy some inappropriate benefit or are not thought to be complying with their responsibilities concerning stock conservation, that is a matter to be addressed at governmental or international level.
"I am dealing with the contravention of a law of this country which was introduced to ensure compliance with the international obligation which the United Kingdom had entered into.
"I am entitled to treat that contravention as a serious matter regardless of how it might be thought that similar conduct would be or has been responded to elsewhere."
Three more fishermen pleaded guilty today in a separate case but which was part of the same investigation.
James Smith, 54, from Fraserburgh, John Smith, 36, from Peterhead and Stephen Bellamy, 59, from Fraserburgh all admitted landing undeclared fish at Fresh Catch in Peterhead and at Shetland Catch in Lerwick.
Sentencing was deferred to May 18.
An inspection in November 2005 at the Alexander Buchan firm detected an unofficial weigh belt fitted with "load cells" to the conveyor belt system at the point where fish entered the factory. The cells are used to detect the weight of fish passing over the belt.
A deflector plate had been used on the unofficial weigh belt, allowing the fish to drop off part of the way along the official scales. As the fish did not travel over the full area, a lower weight was achieved on the counter. This method is said to have allowed up to 70% of a total landing to go unrecorded.
Alexander Buchan, which is no longer trading, has already been ordered to pay £165,000 in a confiscation order.
A third fish processing factory, Fresh Catch, also admitted helping vessel masters land undeclared fish between October 20 2002 and September 2 2005 at its premises in Kirk Square near Peterhead.
Skippers Ernest Simpson, 64, from Fraserburgh, Allan Simpson, 42, from Fraserburgh, and Oswald McRonald, 63, from Banff, pleaded guilty at the High Court in Glasgow today to landing undeclared fish at the factory.
Their sentences were also deferred until May 18.
Fresh Catch was audited by KPMG during the same period as Shetland Catch and it too was found to have earnings unsupported by official landing figures.
At the factory, fish entered via a delivery pipe which went up and over the building. However, a search of the premises in September 2005 uncovered a purpose-built pipe, leading underground, was also connected. This second pipe bypassed the official weigh scale.
Knife valves were used to divert the fish when they came to a T-junction, allowing fish to be sent to another part of the factory and was never weighed or officially accounted for.
In 2005 the two valves become remote controlled and the direction the fish took at the junction depended on which one was open or closed.
Fresh Catch only became significantly operational at around the time the scam began.
Cephas Ralph, head of compliance at Marine Scotland, said the divert pipe "certainly served no other purpose" and that "it wasn't put there by accident".
All three factories were prosecuted out of Operation Trawler which started in 2005. However, nothing suggested any of the plants were linked.
At the time of the undeclared landings, Shetland Catch was the largest pelagic fish processing operator in Scotland and one of the largest in Europe. It was able to process and freeze up to 1,000 tonnes of fish a day.
EU regulations state that when a vessel reaches its quota, it has the option to either stop fishing or to buy some of another vessel's quota which has not yet been reached. Any vessel which exceeds its quota faces disciplinary action.
When the investigation started 26 vessels were in the pelagic fleet, with eight pelagic fish processing factories. More than half (15) of those boats have been prosecuted.
Mr Ralph said the investigation had an immediate effect on the entire industry and that Marine Scotland is now satisfied that legislation is in place to ensure a similar scam does not happen again.
He said: "Since 2005 we detected a change which spilled out beyond the pelagic industry. It is more important to the vessels to have a good reputation.
"It is fair to say we are satisfied that we have inspection procedures, legislation, a mindset in place in the industry that means if such activity was to recommence, it would be quickly detected and dealt with.
"We have not had anything similar since these cases and all our intelligence suggests that no similar activities are taking place."
Afterwards Lindsey Miller, head of the serious and organised crime division of the Crown Office, said: "Organised crime takes many forms. These individuals may not have been involved in drug dealing or prostitution but let us make no mistake that they were involved in significant and serious organised criminality."
She added: "The legislation is there to protect the marine environment for the good of all and to safeguard the future of the fishing industry. These men disregarded it for their own financial gain and, in a clear example of successful working between the law enforcement agencies involved, have now been brought to justice and made to pay for their crimes."
The police investigation was led by Detective Superintendent Gordon Gibson of Grampian Police who said the scale of the crime is of "a level rarely seen before".
The men involved "amassed huge sums of money through their own greed and today this caught up with them in a court of law", he added.
Meanwhile, Cephas Ralph said: "Today's successful court activity is an outcome that reflects the professionalism, dedication and commitment shown by all of the Marine Scotland staff who have been involved in this inquiry.
"It has not been an easy task but they have worked tirelessly to help secure the convictions obtained in these important cases."
Scottish Environment Secretary Richard Lochhead paid tribute to the police and Marine Scotland for their efforts in "a long and vastly complicated inquiry".
He said: "There is no doubt that these illegal activities are a stark and shameful reminder of the culture that existed in some sectors of the fishing industry in past years. But they do not reflect the much-improved culture we see today.
"The offences date back up to a decade ago and thankfully there has been seismic change in the attitude and behaviour of the fishing fleet, which can only be good thing in securing a viable future for the industry in Scotland."
He also said: "There have been significant advances in recent years in how fish landings are monitored and controlled, including comprehensive audits and certified weighing systems."
Dr Mireille Thom, senior marine policy officer at WWF Scotland, said ignoring quotas "isn't a victim-less offence" because "such landings not only undermine the conservation of fish stocks and the fortune of the fleets that fish them, they also distort competition by depressing fish prices. In short, they threaten the public good for the benefit of a few".