In the basement of Glasgow University's zoology building, at the end of a corridor lined with discarded computers, cracked laboratory flasks, old fridges and creaky plumbing pipes, there is a tiny room filled with racks of grey storage boxes. This is an odd, uncomfortable place. The air-conditioning is chilled to near freezing while the boxes are linked together by pipes that are constantly flushed with seawater. It feels more like a showroom for second-hand cisterns than a place of science.

Yet the work carried out in this gloomy little cellar has little to do with plumbing and has much to do, instead, with biological regeneration - for each of these boxes is inhabited by a creature that researchers believe could be saviour of our most threatened industry: fishing. These basement denizens are members of the crustacean family Nephrops norvegicus - usually known as the Dublin Bay prawn, or scampi, or the Norwegian lobster or - most often - the langoustine.

In their grey laboratory homes, Nephrops is a distinctive sight: slim, orange-pink, with long thin claws and black beady eyes. They look utterly alien, strange interlopers or possibly sinister invaders bent on conquering our seabed. Nothing could be further from the truth, of course: Nephrops is one of the most common sea creatures to be found in British waters.

'Indeed, the more we look, the more we find,' says Douglas Neil, the marine biologist in charge of Glasgow's subterranean langoustine laboratory. 'We now know there are huge numbers of langoustine in the Firth of Clyde, the Minch, the North Sea off Aberdeen, the Firth of Forth, and the Farn Deep off the Northumbrian coast.'

These reservoirs have been revealed thanks to a major research programme that has been taking place in Scotland over the past five years, and which has involved scientists investigating the life cycle of the langoustine in laboratories like Neil's, as well as studying their habitats from research ships. In the latter case, underwater TV cameras have even been used to survey the seabed where the langoustine constructs its burrows. By counting the numbers of entrances to their sea-floor homes, scientists have been able to make the first accurate assessment of Britain's langoustine population. And the figure they have come up with is an astonishing one - more than 10 billion. As a result of this discovery, there has been a complete reassessment of langoustine-catching in Britain, with quotas being increased this year by 30 per cent. It is a striking revelation at a time when quotas of all other fish are being reduced as a result of the savage depletion of stocks caused by over-fishing last century.

Nor has this reappraisal come a moment too soon for our fishermen. 'Frankly, langoustine have saved our fishing communities,' says Fred Buchan, the owner of Scotprime Seafood, a shellfish export company based in Ayr. 'If it wasn't for langoustine, then places like Stornoway, Mallaig, Lossiemouth, Buckie, Ayr and Troon would have been destroyed by now. When the white-fish industry died off, the langoustine market materialised just in time to save our boats and ports.'

Consider the story of Eddie Laytona. Eddie, 58, has been a fisherman since he was a teenager and sails his trawler, the Tribune, out of Troon. Over the past five years, he has watched the hake, whiting, plaice, and cod - fish that he used to catch daily in their thousands - disappear from his nets. 'Strict quotas are set on these fish today but really there is no point. There are no fish left. We couldn't get anywhere near those quotas if we wanted to, never mind breach them. On my last trip, I caught a dozen white fish. At the same time, I caught about a tonne of langoustine. If it wasn't for them, I would have nothing to live on.'

Not every fisherman has been so lucky. Those with bigger boats have found it hard to catch enough langoustines to meet the running costs and have sold up. However, many others - usually those with smaller vessels - tell similar stories to that of Eddie Laytona. It has been a strange maritime reversal. Forty years ago, Nephrops norvegicus was viewed as trash - fishermen call it 'by-catch' - and they were dumped overboard when they found in trawlers' nets.

'It's the other way round today,' says Laytona. 'The fish we catch now are so thin and small and miserable we throw them away and keep the langoustine instead.' As a result, Nephrops has become the most valuable, most lucrative species of sea creature that is being landed at our harbours today.

Langoustine are scavengers that feed off worms and smaller crustacea and can grow up to a foot long. In general, the bigger they are, the better they taste. Smaller ones, once caught, usually have their long, muscular tails cut off. The rest of their bodies are discarded and the tail is then coated in breadcrumbs to be sold as scampi.

By contrast, bigger langoustine are sold whole to fishmongers - usually overseas - as a luxury seafood, a market on which Buchan's Scotprime concentrates. He ships his langoustine to the continent, particularly to Spain - a nation whose love of fish is unsurpassed in Europe. Wander into a Mercadona supermarket in Málaga or Seville or Salobreña, and you will see square metres of refrigerated displays of langoustines. Nearly all will have been exported by Scotprime who pride themselves on being able to get langoustines into Spanish supermarkets from Scottish quaysides in just three days.

In this way, the nation's most important and tastiest seafood is constantly being ferried the length of the country and then whizzed across the Channel with hardly any being kept for our own market. Certainly, langoustine rarely grace the British dinner table - the exception being those pre-cooked packets of breaded scampi we find in supermarket frozen-food cabinets.

It is a real waste of a great British resource, for a meal of langoustine is a sublime culinary experience, as Rick Stein makes clear in his Seafood Lovers' Guide. This is an ideal seafood, he stresses. 'The muddy holes they live in might put you off - until you taste them. There is little you need to do with them. Just boil them for four minutes and serve them with garlic butter or mayonnaise.' The tail provides most of the meat, though in larger creatures you winkle out delicate strands of flesh from their claws. At the same time, the discarded shells can be boiled up to make a glorious sharp stock or bisque. Alternatively, you could try cooking langoustine in whisky as I once did on a boat trip round Skye. Moored off the Cuillin, we were sold a dozen by a local fisherman. We plunged them into hot Talisker single malt and brought it all quickly to the boil. The smoky taste of the whisky beautifully offset the sweetness of the langoustine flesh - and, of course, there was the added benefit of knowing that the little creatures must have died happily.

Not that such issues concern fishermen very much. They are merely relieved to have found a market for the most abundant seafood to be found round our shores. Langoustine have saved them - but for how much longer? Having been thrown this lifeline, will our fishing industry this time learn from the mistakes of the past and resist fishing the langoustine to oblivion? Or will it merely repeat the maritime mistakes of the past century? These are crucial questions and they take us to the work of scientists like Douglas Neil, who has been studying the life cycle of Nephrops norvegicus in order to figure out ways to catch it, to store it, and to preserve its delicate flesh both for export and for local use - and in a responsible, sustainable manner. Hence those langoustines that are kept in his laboratory.

For several years, Neil's team - working in partnership with one of the seafood industry's giants, Young's Bluecrest - have been taking blood and tissue samples from Nephrops that have been kept under a variety of conditions. From analyses of blood-sugar levels, they have concluded that anxiety can have a major impact on quality of flesh. 'Langoustine can suffer a great deal of stress when they are first caught, and if they are not properly treated that can have a bad effect on their flesh,' he says. 'They will lose muscle texture and their surface membranes will weaken. Then they will start to go off quite quickly. That can affect prices and catches, so we are trying to find out how best to treat them when they are first caught: for instance by making sure they are properly watered when taken out of nets. Certainly, if we can crack the issue of stress we will be on a real winner.'

Neil holds up one of his little charges for inspection, clasping it carefully behind its head. 'A healthy langoustine should be relatively pale,' he says. 'Intense colouring may seem attractive, but those reds and oranges are often a sign of infection or ill health.'

The creature writhes constantly in his hand and the biologist never takes his eyes off it. 'Those pincers will pierce right through a finger or a thumb. They know how to defend themselves.'

It is the study and subsequent understanding of the Nephrops life cycle that has resulted in the new-found appreciation of their value. 'The great thing about the langoustine is its basic biology,' says Jim Atkinson, of the Millport marine biological research station in the Firth of Clyde.

'We have found they live in burrows below the seabed for long periods of their lives: principally when females are bearing eggs and also after these eggs have hatched and the young langoustine are still growing. They spend the first two years of their lives in these burrows and that is good news. Down there, they cannot be caught in nets and that in turn means we should always have a basic protected stock of langoustine. That is something we never had with white fish.'

It is a comforting prospect, though other experts counsel caution. In Spain, reserves of langoustines have declined in recent years. Biologists remain unsure of the cause though over-fishing is an obvious candidate. 'There are lessons to be learned from Spain, that is certainly true,' admits Neil. 'In addition, we have found there are some key moments in the lives of langoustine when which we have to be careful about how we deal with them. For example, females moult in April and May. Their shell loses its hardness and the flesh becomes quite jelly-like. We need to avoid fishing them at this time.

'The crucial point is that we are now looking at the life cycle of a creature that has great potential as a seafood resource - and trying to understand what problems and pitfalls lie ahead. In the past, we have only taken such an approach with a fish - like the cod - once it has already got into trouble. By the time we have worked out the problem, and understood its life cycle, it has been too late. Cod stocks have already dropped to dangerous levels and we have little room for manoeuvre. That is not the case with the langoustine. We now have the knowledge to sustain numbers and give our fishermen a real chance for survival. It is up to us not to mess that up.'

The life and times of the langoustine

Nephrops norvegicus is a seawater crustacean that is caught mainly in nets trawled across the sea floor, though a small minority are trapped in individual creels. For the first two to three years of their life they hide in burrows on the seabed. Once they've reached sexual maturity, they leave their burrows and explore the seabed.

Other edible shellfish found in British waters include its larger cousin, the blue lobster, and various species of crab. The crayfish, by contrast, is a freshwater crustacean.

Freshwater prawns, such as the tiger prawn, which we buy in supermarkets, are usually farmed in the Far East or South America while shrimps like the northern or Maine are fished in northern seas like the North Atlantic and the Barents Sea. Potted shrimps are much smaller and fished by inshore fishermen in the Wash, Morecambe Bay and the Solway Firth.