Countryfile – Mersea Island

Countryfile – Mersea Island follows Anita Rani to one of the most distinctive corners of the Essex coast, where oysters have been harvested for more than 2,000 years and where a single tidal road still decides who comes and goes. It is the latest leg of her East Coast Road Trip, a journey up through Essex and into Suffolk that examines how coastal communities and wildlife are adapting to relentless tides, erosion and a changing climate. This week, the focus is unashamedly singular. As Anita puts it herself: “Today is all about oysters. Oysters, oysters, oysters!”

The stakes, however, run far deeper than a plate of shellfish. Disease, overfishing and warming seas have forced the industry around Mersea Island to reinvent itself. The native flat oyster that fed Roman Colchester was almost wiped out in the 1970s, and the Pacific rock oyster that replaced it has since escaped into the wild, building reefs that scientists can no longer remove — and may no longer want to.

Between a working oyster boat on the Pyefleet estuary, a research trip to a sprawling rock oyster reef near Brightlingsea, and a barbecue on the shoreline, the programme captures an industry balancing ancient heritage against ecological uncertainty. Along the way, archive stories from Wales, the Severn Estuary and the west coast of Scotland widen the lens, showing how people across Britain are learning to farm, fish and restore the sea on its own terms.

Anita’s first discovery arrives before she even reaches the island. The road connecting Mersea to the Essex mainland floods completely, and crossing is only possible at certain times of day. “That’s what cuts this place off from everywhere else,” she observes, watching the water creep across the tarmac.

Locals treat the phenomenon with a mixture of pride and mild exasperation. Every spring tide, roughly every couple of weeks, the island is cut off — recently around 11am and 2pm, and again in the evening. Cars regularly get stuck, drivers abandon them, and the lifeboat is called out to pluck stranded motorists from their vehicles, sometimes while they sit on their roofs.

Islanders are in no hurry to change any of it. “Don’t tell too many people,” one resident jokes when Anita asks what life there is like. The isolation is part of the identity. For Anita, arriving by camper van, it sets the tone immediately: a place where the sea, not the clock, dictates the rhythm of daily life.

Countryfile – Mersea Island

Countryfile – Mersea Island Introduces Paul Harding and 2,000 Years of Oyster History

Out at East Mersea, Anita joins local oyster fisherman Paul Harding, a man who has worked in the industry on and off for around 25 years. His reasoning is disarmingly simple: he loves seafood, he loves eating, and no two days on the water are ever the same.

The history he carries with him is anything but simple. Native flat oysters have been fished in these creeks since Roman times, when Colchester was the capital of Britain. Romans towed Mersea oysters back to Rome, and their shells have been found in Roman ruins. Until the mid-1970s, those natives were the only oysters here. Then a disease called bonamia arrived and wiped them out.

That collapse changed everything. Pacific rock oysters were allowed into the rivers as a replacement, and Paul is blunt about the consequences: without their introduction, there would be no oyster industry on Mersea at all. Rock oysters grow faster, resist disease better and cope more readily with warming sea temperatures. Consequently, the species that saved the fishery was never native to it — a tension that runs through the entire episode.

Hatchery Seed, Growth Rings and the Business of Farming Two Million Oysters a Year

On board the boat, where the crew have been working the Pyefleet estuary since 6am, Paul lays out the economics of modern oyster farming with striking clarity. The fishery buys in seed from specialist hatcheries — around two million juvenile oysters a year — and lays them on the estuary bed. Roughly 80 per cent come back as harvestable stock.

That predictability is the whole point. Relying on wild oysters means one bad spawning year can leave the beds empty two or three years later. Buying seed takes the risk out of farming and keeps stocks permanently replenished. Four more tons of seed were due to arrive the day after filming, to be sent down chutes off the back of the boat, with the propeller wash scattering them evenly across the bed.

The growth rates astonish Anita. An oyster bought at thumbnail size reaches its ideal, saleable size within about 18 months, fattened by nutrient-rich water flowing off the marshes and refreshed by the sea twice a day. Paul shows her the growth rings on a shell, laid down season by season like the rings of a tree. Even rainfall leaves its mark: heavy rain lowers salinity, and the oysters slow their growth in response.

Katie Harding Traded a Marketing Career for Seven-Hour Shifts at the Sorting Table

Some of the warmest moments in Countryfile – Mersea Island belong to Katie Harding, Paul’s wife, who works the sorting table. Her route to the boat was anything but traditional. Her background is marketing, advertising and building websites — “sitting behind a computer all day, every day.” Ten years ago, she would never have believed this would be her living. Now she says she will fight tooth and nail to stay on the boat rather than return to an office.

Katie teaches Anita the sorter’s essential skill: telling live oysters from dead ones by sound. Tap two live oysters together and they clack like rocks. A dead one sounds dull and hollow. Live oysters of the right size go in the bucket; small ones go back over the side to keep growing; clumps get broken apart where possible.

The job is undeniably hard. Katie stands at the table for around seven hours at a stretch. But the compensations are constant — seals, marsh harriers and oystercatchers for company, and the knowledge that she is doing exactly what hundreds of boats did on this river before her, in pretty much the same way. Even the oysters have personality. “We like a wonky oyster,” she tells Anita, holding up a shell that has grown sideways. It is the long, thin ones the fishery sends back.

Why the Hardings Say Dredging Prepared Beds Is Farming, Not Damage

Dredging carries baggage, and Anita puts the question directly: does dragging a dredge across the seabed upset the oyster beds? Paul’s answer reframes the whole practice. These beds have been dredged for as long as anyone can remember, and the fishery only works ground it has always worked — beds deliberately prepared with layers of cockle and oyster shell.

His comparison is drawn straight from the land. A farmer ploughs his field; he doesn’t plough the countryside. The fishery, which has worked this stretch since the 1960s and holds the fishing rights for the river, operates on exactly the same principle. Surrounding areas that have never been farmed are left alone, and the team is careful about where the dredge goes. “It’s a traditional industry,” Paul says. “We have to protect it because this is our bread and butter.”

He goes further, calling this the most sustainable form of aquaculture there is. No electricity is added. No fertiliser. No fresh water. The oysters are laid down and nature decides the outcome. The claim gains weight when a genuine rarity comes up in the dredge: a true Colchester native, probably six or seven years old. Nobody keeps it. It goes straight back into the river to carry on growing and spawning, part of a deliberate effort to rebuild a natural, self-sustaining native population. Anita gives it a stroke and a send-off: “Go, repopulate!”

Countryfile – Mersea Island Confronts the Pacific Rock Oyster Problem Head-On

The second half of the episode turns from farming to ecology, and to a question with no comfortable answer. Ecologist Tom Cameron from the University of Essex takes Anita towards Brightlingsea, along with researchers Lola and Kristina, to stand on something she has never seen before: a wild Pacific rock oyster reef, stretching as far as the eye can see.

The backstory is a cautionary tale about unintended consequences. Government helped introduce the rock oyster because shellfish stocks were declining, on the assumption that British waters were too cold for it to breed. Climate change put paid to that. The species is now fully naturalised, “well beyond the point of any chance of serious control,” as Tom puts it.

His honesty about the dilemma is refreshing. He would click his fingers and make the rock oyster disappear if he could — but that is not the world we live in. Britain already lives with parakeets, mandarin ducks, invasive crayfish and crassula in its fresh waters. The rock oyster, he argues, is simply the marine equivalent. The research question has therefore shifted from eradication to adaptation: if we cannot beat this species, what can it do for us?

Living Sea Defences: How Rock Oyster Reefs Could Protect an Eroding Essex Coast

Standing on the reef, Anita is surprised by how deep it runs. The team has measured reef heights of metres upon metres, built up as old oysters die and new generations grow on top of them — three or four shells fused together, only one of them alive. That structure, Tom explains, is precisely what makes these reefs so valuable.

The comparison he reaches for is a coral reef. A landowner worried about wave erosion could import rocks year after year as the water rises. Or the coast could rely on a living sea defence that builds itself. As sea levels climb, the lower oysters die and new ones grow above them, so the reef rises with the water and keeps protecting the shore. For a coastline already suffering erosion of sand cliffs and salt marsh, that is potentially a solution hiding in plain sight.

The biodiversity findings challenge assumptions too. Fears that rock oysters would smother mud flats and displace feeding birds are not supported by the data. Curlews, lesser black-backed gulls and oystercatchers are already finding food on the reefs. “Long since we are still arguing about it, they’ve already adapted to it,” Tom notes. His surveys find essentially equal biodiversity on rock oyster reefs as on mussel reefs or native oyster reefs — different species, including some periwinkles a rock-pooler would recognise, but not less life.

The reef does harbour some additional non-native species, hitchhikers from the less cautious introductions of the 1960s, and Tom concedes the benefits may not outweigh concerns everywhere. In many places, though, he believes they can. The visit ends with a scramble as the tide races in around Anita, who has broken what she calls Countryfile Rule 101 — she forgot her wellies.

From the Archives: Seaweed Farming in Wales and the Last Lave Net Fishermen of the Severn

True to the road-trip format, Countryfile – Mersea Island weaves in archive stories of other people working with the sea. In 2024, Charlotte and Joe visited Car-y-Mor off Ramsey Sound on the Pembrokeshire coast — the first regenerative ocean farm in Wales, founded by Francois Beyers and his family. He calls it an underwater garden: shellfish and seaweed grown together, each species feeding the others, creating fish nurseries and drawing seals through the kelp during pup season.

The farm harvests mussels, crabs and up to 120 tons of seaweed a year, most of it for food. Farm manager Nigel Robinson shows off sugar kelp cut six inches above the “roots” so it regrows, and the black sorus patches that supply seed for next year’s crop. Seaweed can grow up to two inches a day, sequesters carbon and filters phosphorus and nitrates out of the water. The name means “for the love of the sea,” and the farm is now planning another eight hectares.

A second archive story, from Matt’s 2020 visit to the River Severn, strikes a more elegiac note. Brothers Martin and Richard Morgan are fourth-generation lave net fishermen at the Black Rock Lave Net Heritage Fishery, founded by their great-grandfather and then celebrating its centenary. They wade into a five-or-six-knot tide, feeling for salmon through the mesh with their fingers, in murky water where nothing can be seen. Only eight licences exist, so scarce they are known as “dead men’s shoes.” A season might yield between two and nine fish. For retired steelworker Martin, none of that matters: fishing on his own doorstep “means everything.” The fishery fears it may be the last generation to do so.

Salt-Marsh Lambs on the Gower and Seawilding’s Native Oyster Revival in Scotland

Two further archive visits complete the coastal picture. On the Gower, farmer Dan Pritchard rears salt-marsh lambs on common grazing shared by six or seven farms, gathering the flock every two to three weeks around the high tides. The tide book governs everything, even family holidays. Salt-tolerant plants — sea lavender, sea sorrel and emerging samphire — give the lamb its distinctive taste, recognised with Protected Designation of Origin status after 75 years of family farming.

The most direct counterpoint to Mersea comes from Loch Craignish on Scotland’s west coast, which Hamza visited in 2023. There, the Seawilding project led by Philip Price is doing the opposite of Essex: rather than embracing rock oysters, it is painstakingly restoring natives. Native oysters once numbered in the hundreds of millions, possibly billions, around Britain before overfishing, pollution and dredging emptied the seabed. Seawilding has already returned 300,000 to the loch, with a target of one million, using community casting days that draw volunteers from two-year-olds to eighty-year-olds.

The project pairs oysters with seagrass, and the partnership is remarkable. Oysters filter and clean the water, giving the light-hungry seagrass what it needs to photosynthesise; seagrass in turn reduces acidity, protecting calcium-based animals like oysters from increasingly acidified seas. Marine scientists Katherine Knight and Eric Holden are pushing further still. In a UK first, licensed by NatureScot, they are transplanting seagrass rhizomes — likened to strawberry runners — instead of growing from seed, creating instant meadow. Globally, an estimated two football pitches of seagrass are lost every hour, which makes their result all the more striking: 3,000 square metres of new seagrass habitat created since filming, with plans to expand across Scotland.

Shucking Lessons, Barbecued Oysters and a Bloody Mary Finale on the Shoreline

Back on Mersea, the day ends the only way it could: eating. Local chef Dave Wall meets Anita and Paul on the shore and teaches her to shuck her first-ever oyster — knife worked side to side, muscle cut beneath the lid, top shell lifted away. She eats the spoils of her own labour on the spot. “Fresh as it gets,” she declares.

Then comes a revelation for anyone who thinks oysters must be eaten raw. Dave sets whole oysters straight onto the barbecue, where the juice inside bubbles, steams the meat and forces the shell open as the muscle releases. He dresses them with a rough-and-ready wild garlic gremolata, and recommends cooked oysters as the ideal entry point for the apprehensive. Anita, tasting her first hot oyster, vows to recreate it at home. A final flourish arrives in the form of a Bloody Mary oyster — tomato juice, vodka, Tabasco and celery — and Tom Cameron, joining the gathering, adds a scientist’s endorsement: oysters are full of vitamins and minerals, their exact balance shaped by the waters they grow in.

Even the farewell is dictated by the sea. The tide is coming in, the causeway will soon flood, and Anita has to get back on the road. Her next stop lies 25 miles up the coast at Walton-on-the-Naze, the most easterly point of Essex.

Countryfile – Mersea Island ultimately lands on a quietly optimistic idea. The same waters that carried Roman oyster boats now carry a fishery rebuilt around a foreign species, a research team rethinking what “invasive” means, and reefs that may end up defending the coastline itself. On an island the tide still cuts off twice a day, adaptation is not a strategy. It is simply how people have always lived.

FAQ Countryfile – Mersea Island