Carved out of the Cornish coast, the 40-acre fishing port of Newlyn nestles between picturesque Penzance and idyllic Mousehole. With a staggering diversity of seafood landed there each day, it is at the heart of Cornwall's fishing industry and in value terms is the largest fishing port in England and Wales.

Newlyn is also home to Seafood Cornwall, the organization that supports the seafood industry in that region which, along with the Sea Fish Industry Authority (Seafish), hosted a recent Craft Guild of Chefs study tour to the area. Aiming to give the chefs an insight into what it takes to get fresh seafood on their menus, the tour started in the late afternoon down on the docks greeting the fishermen coming in from the sea.

The crew aboard Little Pearl had been out since 5am fishing the waters around Lands End and the Isles of Scilly. Just under 10 metres long, the boat was originally built as a trawler but current owner David Pascoe refitted it with ring nets to capitalise on the growing demand for Cornish sardines.

The rebranding of the humble pilchard into the Cornish sardine was largely due to local businessman Nick Howell, who the group also met at the quayside.

After running the century old Pilchard Works, pressing and salting pilchards for export to Italy, in the last decade Howell has championed the fish's reincarnation into the omega 3 rich sardine, promoting it as a fresh fish option to major retailers such as Marks & Spencer.

“We used to bring in around seven tons of sardines in 1997 but now we land nearer 2,000,” said one fisherman. “The fish have always been there, but now there's more demand with retailers such as Tesco selling them prepacked and ready to go on the barbecue.”

Aside from sardines, the Little Pearl brings in anything from monkfish and pollack to spider crab, crayfish and lobster. Capable of holding eight and a half tons of fish onboard, its biggest catch that week was 100kg of turbot, which would sell at the market for between £13-£14 a kilo.

Offering a taste of life at sea the chefs were invited onboard Sea Spirit, a small day boat owned by Quentin Knights, who spends most of his waking hours handline fishing for mackerel. His passion for his work soon rubbed off on the group as they were taught to handline the mackerel themselves, bringing in a number of iridescent striped examples.

Knights explained that their intense blue-green colour begins to fade when the mackerel comes into contact with the fresh water from the ice they are packed in.

The use of ice bins onboard the boats is a fairly new initiative that Seafood Cornwall has been pushing and, according to Nathan de Rozarieux, project director for the organisation, the introduction of the bins has been one of the “biggest changes to inshore fishing in a generation”.

The insulated bins can hold ice for up to a week, so the fish can be gutted and cleaned and layered with ice at sea, improving the freshness considerably.

“We are really pushing the new packing boxes. They cost around £200 each but we've received £100,000 in different grants and funding for supplying small boats, of which 75% comes from a European grant,” explains de Rozarieux.

Newlyn boasts one of the country's biggest fishing fleets with vessels ranging from the small day boats to deep-sea trawlers. De Rozarieux provided the chefs with an overview of the several different fishing methods used such as traditional stern trawling and beam trawling.

It came as a surprise to the group that modern beam trawling equipment now in place on some of the boats is having less of an impact on the environment than expected.

“The new benthic release panel on beam trawlers reduces the catch of non target species like starfish, etc, and almost all of the beam trawlers used now have wheels on them so they can glide along the seabed, disturbing it less. Smaller boats also tend to work the same areas for years, so it's a bit like rotation farming,” adds de Rozarieux. There are only 75 licences for beam trawlers in the southwest and the high cost of crude oil means they often struggle to break even.

Gary Hunter, head of culinary arts at Westminster Kingsway College, was in the process of writing a chapter on the fishing industry for a series of catering textbooks to support the new NVQ and Diploma qualifications, and found the trip enlightening. “It was interesting to find out about the new equipment being used and to hear first hand the opinions of the fishermen. I will be rethinking what I am writing for the book, incorporating what I've learnt here so we can educate young chefs,” he said.

Ring netting is a traditional method, which has its roots in 16th century Cornwall but has enjoyed a revival in the last 10 years. It uses sonar to track large shoals of fish such as herring or sardines. Nets are then shot around in a ring, surrounding the fish. It is a more sustainable method, targeting single species of fish, which are landed within two or three hours. Gill nets, which are set on the seabed to create a wall 10ft-15ft high, can be left for 24 hours, while tangle nets stay down for two or three days.

A growing number of fishermen are turning to the traditional method of handline fishing as consumers are increasingly prepared to pay a higher price for quality, sustainability and trace ability.

The South West Handline Fishermen's Association has established a tagging system for handline caught fish such as bass and pollack. “Once the fish is caught, it is brought down to temperature within the hour ensuring it is as fresh as possible. The fishermen attach a tag, which remains on the fish until it reaches the end consumer,” explains de Rozarieux. “As well as a guarantee of quality and freshness, the fish can be traced back to the very boat it was caught on.”

The group was able to see the tags for themselves at the market the next morning, where around 30 or so buyers descend upon Newlyn in the early hours of the morning for the daily fish auction. The variety of seafood on offer is impressive, with more than 25 different species coming in from one boat. Crates are piled high with skate (weighing up to 12kg), ray – which will appear on most menus as skate, huge conga eels, monkfish, pollack, mackerel, even shark.

Robert George, an ex skipper who now works on behalf of Seafood Cornwall liaising with the fishermen on quality control, gave the group a fish quality master class. He has developed a bespoke quality assessment programme where boats are given a scorecard. Based on the widely used Torry scale, the fish's gills, eyes and skin are examined and the boats are scored on everything from the way the fish has been gutted to how well it's boxed.

Temperature is of paramount importance and if it is too high or too low this can affect the score drastically. “Sometimes the fish can be too cold. If the fish is flash frozen, that is fine, but if it is room temperature and then slowly frozen, ice crystals are created which bruise or destroy the flesh,” explains George. “The lowest temperature the fish should be is –0.5ºC and nothing should be over 3ºC. Most are between 0-1.5ºC.”

Leaving the port behind, the group's next stop was nearby shellfish merchants W Harvey & Sons, where a warehouse full of huge holding tanks, capable of storing 30 tons of shellfish, was teeming with live crabs.

Along with scallops and lobsters, the family run business established in 1955, processes 15 tons of brown crabmeat per week, producing around 30-35 tons of shell waste.

Everything is processed by hand. “Hand picking the crab meat makes a huge difference to the end product,” explains Matthew Harvey. “When it's blown, it becomes more of a pulp or mush, but if it is hand picked it retains its texture.”

While the majority of demand is for brown crabs, the popularity of spider crabs is on the increase and the company started selling spider crab meat a few years ago. “Very few people deal with spider crab, they mostly want brown crab. But places like Jamie Oliver's Fifteen are now putting it on the menu, and there's no price difference. If anything, spider crab is a couple of pounds cheaper per kilo. Spring and early summer are the best times for them,” adds Harvey.

Most of the company's processed crab and spider crab meat is exported to France and Spain, but the company is keen to break into the English market.

While five years ago all exports were live, now most of it is processed. For example it produces 5kg sandwich packs, which are pasteurised and vacuum packed with a 5-6 week shelf life. “Our customers are changing. French housewives used to pick their own crabmeat. Now they are busier and are not preparing meals in the home the way they used to.”

Demand is high however, and the company says it has doubled its output this year. “Whenever Rick Stein's on television, our fishmongers say sales go up considerably.”

Matthew Stevens & Sons, based in nearby St Ives, is another family run seafood processor and the group was given a tour of its purpose built premises, where the seafood is now processed 24 hours a day. “To meet demand we've just introduced a night shift,” says Matthew Stevens.

Fish is brought in daily from Newlyn and other ports in the southwest such as Plymouth and Brixham and is hand scaled, pinboned, and portioned. “We do around 11 different processes, from filleting to pocketing,” explains Stevens.

In the delivery bay crates are stacked bearing the names of restaurants around the country. “We drop into London around six times a week, from Tom Aikins to Gordon Ramsay. The Wolseley for example takes 200 pollack portions, and we supply the Tate Gallery with line caught pollack.”

Passionate about both his company and the seafood industry, he is constantly developing the business to stay a step ahead, from becoming more environmentally friendly to coming up with new product ideas.

“We've gone from being 100% landfill to now only 3%. We have introduced plastic boxes for our deliveries to chefs, so they come back and are cleaned and reused,” says Stevens.

One of his latest product lines is the Cornish trio – a vacuum packed portion of three mini fillets, such as lemon sole, haddock and monkfish, which sells for around £2.

Having been in the fishing industry all his life, he has seen how consumer trends for different species have changed over the years. “I remember a time when you'd see monkfish floating out of the harbour – no one wanted them, and we used to wrap ling up in newspaper to give to cats. The demand for Cornish seafood now is international. It's appearing on menus at places such as the Burj al Arab in Dubai.”

While there is a healthy export market for UK seafood, according to Seafish the UK is becoming increasingly reliant on imports, with a rise of 39% between1995 to 2004. Stevens would like to see more UK chefs and consumers buying British.

“In two or three years if we can get local seafood, processed by local people, sold in this country – with no foreign lorries making deliveries – I'd be thrilled,” he says.

It's a message that certainly rubbed off on the group: “The trip was an absolute eye-opener and will definitely impact on the way I order and treat fish,” said Steven Poole, chef director of the Food Bureau. “The passion shown by these guys – both the fishermen and the processors – was impressive.”