Northern Ireland's eel industry faces a major crisis if the problem over the supply of young fish is not solved, it has been warned.
No-one knows why there has been such a serious decline in elvers
Their commercial fishing is based at Lough Neagh - the sole surviving major wild eel fishery in Europe.
Total annual output of eels from the lough is about 700 tonnes, with most exported to Holland.
However, in recent years the natural supply of baby eels, known as elvers, has dramatically declined.
The situation became so bad that the Lough Neagh Fishermen's Co-operative Society - which regulates the industry - was forced to start buying elvers from England.
More than 70 million have been imported since 1985.
It is a move which has strengthened the Northern Ireland industry, as many fishing concerns throughout mainland Europe are in terminal decline.
However, the Co-operative believes if the situation is not resolved then the jobs and livelihoods of about 300 fishermen could be in jeopardy.
The problem is that no-one knows why there has been such a serious decline in elver numbers.
Father Oliver Plunkett Kennedy, the Co-operative's managing director, says in a normal year prior to 1984 there was the equivalent of eight million elvers arriving in the lough each year.
In 1977, the figure was more than 19 million, and in 2001 was just 945,000.
Buying the elvers is a costly business, and so far the Co-operative has spent more than £1m on replenishing supplies.
The price of elvers has risen from £29 per kilo in 1985 to a peak of more than £500 per kilo in recent years.
'Right combination of weather'
The industry in Northern Ireland also faces stiff competition from a growing number of commercial eel farms in Holland which offer a cheaper alternative to Lough Neagh's wild product.
If the situation is not reversed, many fishermen may leave the industry. Catching eels is a tough life, with fishermen who hunt silver eels staying out on the lough overnight.
"Fishing for silver eels is dependent on the correct weather conditions, as they do not migrate in daylight or strong moonlight," says Fr Kennedy.
Total annual output of eels from the lough is about 700 tonnes
"You have a confined spell of 7-10 days each month and if you get the right combination of weather - which basically means flood conditions on the river and strong south-west winds - then you can catch a lot of silver eels.
"The total silver eel catch has fallen in recent years, from more than 9,000 80lb boxes in 1965, to just 3,144 last year."
One solution to the problem, says Fr Kennedy, is for restrictions to be placed on the export of elvers from England and mainland Europe to the Far East.
In the last 18 months, the European Union has started to take an interest in the commercial eel fisheries in Europe and recognised they are in crisis, he says.
Measures have been proposed to restore the fisheries, including a prohibition or major cutback in the fishing of silver eels.
"Understandably, since we took the precaution of buying elvers in order to maintain the viable status of our fishery, we are reluctant to start allowing a lot of those silver eels to escape in order to compensate for the folly of other management systems in Europe who didn't do that," says Fr Kennedy.
Elvers are thought to originate in the Sargasso Sea
One theory why the elver population has declined is global warming.
They are thought to originate in the Sargasso Sea in the North Atlantic and taken by the Gulf Stream to the waters of the British Isles.
They are then collected at Coleraine on the north coast and transported to Lough Neagh.
However, some believe global warming has affected the Gulf Stream's direction and steered the elvers away from the Northern Ireland coast.
"Assuming for the sake of argument all the speculation about the decline in eel fisheries in Europe is correct, there is no conceivable doubt that we are heading into a crisis situation," says Fr Kennedy.
"We have stalled that by buying elvers, but if it reaches a stage where either we don't have sufficient money to buy elvers, or if there are not sufficient eels escaping European waters for elvers to come back and be available for purchase, then we are all in serious trouble.
The industry in NI also faces stiff competition from Holland
"There are two people fishing per boat, and therefore you have in the region of 320 people depending directly on eel fishing. In turn, they employ other people to prepare lines and for other duties.
"So you have about 300 families around the lough depending on the industry.
"As far as our staff here are concerned, if we don't have sufficient throughput of eels we won't have enough work to keep them fully occupied."