Spirals in Time: The Secret Life and Curious Afterlife of Seashells (17 page)

CHAPTER FIVE

A Mollusc Called Home

T
he next time I encounter oysters I can’t actually see them, but I know they are there. Standing at the end of Mumbles pier, I look down onto the cloudy, sage-green water, ruffled by westerly winds that are scudding across Swansea Bay and making today a bad day for going out on boats. On the other side of the bay are the looming towers of the steelworks at Port Talbot, a sight often compared to an industrial version of Mordor. Over here on this western side things feel much friendlier.

If the weather had been kinder I would have joined fisheries scientist Andy Woolmer aboard his faithful workboat
Triton
, and helped him hunt for oysters. We would have dragged a small dredge along the seabed, four or five metres beneath the waves, and pulled it up now and then to see what
was down there. If the water had been clear, we would have lowered down a video camera to see what we could see.

Instead we walk out across the water. The Mumbles pier was built more than 100 years ago, and is now in the process of being restored; at one end, next to the beach, there’s a noisy amusement arcade, and a shiny new lifeboat is stationed at the other end. We look out at the twin bumps of the Mumbles islands (some say their peculiar name originated in their feminine curves.
What a lovely pair of mumbles
…?). Andy points out the orange buoys that bob at the surface, marking out the place where a few years ago he found a derelict oyster bed.

In 1898, when the pier was built, an oyster fishery was still flourishing in Oystermouth, the town that overlooks the Mumbles. It employed hundreds of people, and traded millions of oysters across the British Isles. Ghosts of the fishery haunt the coast today. There are tumbled wrecks of oyster boats and the low walls of enclosures known as perches are still laid out across the sand where oystermen would store their catches for a few days, toughening them up and getting them used to shutting their shells and staying alive in dry air before their long rail journey to London. Oyster bars and stalls used to be a common sight in the town, and local pubs served up carpet-bags – steaks stuffed with oysters – washed down with pints of thick, dark stout. Back then, oysters were a food for everyone, not just the well-to-do.

Until the 1920s, the new oyster season was welcomed each year with a great celebration for the whole town. Using the piles of empty shells from the oyster-processing plant, children constructed shell grottos, like calcium carbonate igloos, and lit candles inside to make them sparkle. People strolling along the seafront would offer pennies to the grotto-makers.

This part of South Wales has a long history of oyster-fishing. More than 300 years ago, the oyster beds at Oystermouth were
described as the most prolific in Britain. It is even thought that the Romans gathered oysters from these waters during their occupation of the region from the first century ad; there are the remains of a Roman villa in the town, and recently a midden of oyster shells has been uncovered on Mumbles Hill, overlooking the sea, but this has yet to be dated. In Oystermouth today, however, there are no oystermen, no oyster stalls, no carpet bags and no shell grottos.

It was Andy Woolmer’s idea to try to restore the oyster fishery at the Mumbles. If it works, he will bring back not just a lost fishery, but a lost ecosystem as well.

In a similar way to individual trees that grow into a forest or the corals that form the structures of a tropical reef, oysters are also wild architects. Around the world, various oyster species form great gatherings and create beds, banks and reefs that shelter a myriad of other living things. Sedentary species find nooks to nestle in; grazers find green, red and brown seaweeds to chew on; scavengers never go hungry. These assemblages of species, interconnected and relying on each other in so many ways, are what ecosystems are all about. And it was in fact a study of oysters that originally paved the way for the modern science of ecology.

When Karl Möbius explored the Bay of Kiel oyster beds off the German coast, it was primarily with economics in mind. In the 1860s he was tasked by the Prussian government with finding ways to boost harvests of the sought-after and lucrative shellfish. Möbius concluded that farming was not an option for oysters in this part of the Baltic Sea, but from his research a bigger, more important idea came to light.

Getting well acquainted with the great piles of oysters, a mingling of living and dead shells, Möbius was struck by the variety of other creatures that live among them, the fish, crabs, worms and starfish. He was convinced that oyster beds were far richer in life than anywhere else on the seabed, and
in 1883 coined the word
biocönosis
to describe these living communities.

His revolutionary idea was to consider not just single species, one at a time, but the teeming throng of interacting life. It would be another 50 years before the term ‘ecosystem’ arose, taking this concept one step further to embrace both Möbius’ living
biocönosis
and the non-living physical environment, the seawater, rain, soil and so on. At the same time that Möbius was laying down some of the foundations of ecology, the oyster beds and their self-made ecosystems, which kick-started his ideas, were being swiftly dismantled.

European coasts were once fringed with oyster beds. It’s impossible to know for sure exactly how extensive they used to be, but there are clues. A colourful drawing in the 1883 book
Piscatorial Atlas
shows the distribution of the Native Oyster,
Ostrea edulis
, in Europe. This was based on data gathered by the book’s author, Ole Theodor Olsen, who spent years travelling around, talking to fishermen and asking them about the seas and the things they found there. Olsen’s map shows that the French, British, German and Dutch coasts were crammed with oysters, as was the English Channel, the Waddenzee and a huge southerly patch of the North Sea.

The immense scale of European oyster habitat was matched, and in time exceeded, by the scale of their exploitation. During the nineteenth-century heyday of oyster fishing, it was said that three men in a small sailboat could easily dredge up 3,000 oysters in a couple of hours. By the middle of the century, half a billion oysters were passing through Billingsgate Market in London each year.

Nevertheless, as with most natural bonanzas, the riches were not to last. By the beginning of the twentieth century, a feast that had been going on since Roman times was shuddering to a halt. New railways had boosted the capacity to meet demand from hungry inland markets; fishing boats became larger and more powerful; dredging gear grew bigger,
heavier and more effective at scraping things up from the seabed. To make matters worse, the seas were for the first time becoming seriously polluted by the outpourings of factories and mines as the industrial revolution gathered pace. Overfishing and dirty seas alone would have been enough to send European oyster beds spiralling into decline, but one more factor sealed the deal: the remaining oysters were hit by mysterious and deadly diseases.

The demise of European oysters is not a one-off. Oyster habitats formed by dozens of different species used to reign in many places around the world but have been stripped away by a similar litany of ecological catastrophes. Globally, around 85 per cent of all previously known oyster beds, banks and reefs are gone. This decline is the average figure pulled from a large before-and-after dataset of 144 estuaries, mainly in North America, Australia and Europe, spanning the past 130 years. The actual losses could be even worse, because some of the early information was gathered when people had already begun to suspect that oysters were not doing so well. Surveyors were dispatched to see what was going on, often mapping the habitat by touch, feeling their way across the seabed to figure out where sharp shell reefs were growing. By the time they were surveyed, many areas had already started to degenerate from their former unspoilt state.

Despite that, no oyster species have gone extinct. They still live here and there, but only as sparse sprinklings across their former ranges. In Europe, almost all that remains of the giant oyster beds are piles of empty shells. That’s what Andy Woolmer found in 2010 when he led a survey of 100 miles of coast along the south-western tip of Wales that points across St George’s Channel to Ireland.

Andy’s search area stretched between Swansea Bay and Milford Haven. Before setting out, he combed through archives of fishermen’s records to see where oyster beds were historically known. He then went to have a look
himself, to see what was still there. His team lowered video cameras into the water to search for signs of oyster life, and samples of seabed were scooped up and inspected. Among a smattering of living adult oysters, Andy found signs of new threats, including the recently arrived parasite
Bonamia
. These disease-causing microbes first arrived in Britain in the 1980s, and since then they’ve slowly been spreading around the coast, possibly carried by infected larvae. Most infected oysters appear normal, but under a microscope tissues from an adult oyster’s heart or gills will show tell-tale signs of the spherical parasites. And four out of five infected oysters will die.

Another problem is a mollusc that doesn’t naturally belong in British waters but hitch-hiked across the Atlantic when American oysters were imported in the 1880s in attempts to boost the failing native population. This is the Slipper Limpet, which lives clamped together with others of its kind in sex-changing piles and produces copious quantities of sticky goo (this is the limpets’ pseudofaeces, the unwanted food they spit out before digestion). This smothers the seabed and prevents young oysters from settling. In other parts of the country – but not yet in Wales – a second invasive mollusc, the American Sting Winkle, has a greedy appetite for oysters. Having left behind their natural predators in their home waters, they tend to do rather well at the Native Oysters’ expense.

As Andy found out, Welsh oyster beds were clearly in a sorry state, but he didn’t think all was lost. Attending a workshop on the possibilities of oyster restoration and surrounded by scientists discussing the subtleties of oyster biology, Andy decided it was time to stop talking and start doing something: he wanted to see if he could put oyster beds back in the Welsh sea.

There were several reasons why he chose the Mumbles as a test site. It is one of the few areas the
Bonamia
parasite has not yet reached; it is also within reach of Andy’s base in
Swansea harbour. Using high-resolution sonars borrowed from the Welsh Fishermen’s Association, he scanned the seabed, and located several derelict oyster beds. These old piles of empty shells would form the spawning grounds for a new population. Working with experienced oyster fisherman Fenton Duke, he established the Mumbles Oyster Company.

‘I wouldn’t put my millions into oysters,’ Andy tells me. Not that he has millions to invest, but he makes it clear that this venture is not about making money. His dream for the Mumbles is to create a fishery that is sustainable both economically and ecologically; that means a fishery that isn’t reliant on external funds to keep going and one that will allow the oyster beds to flourish as an ecosystem for many years to come.

The team at the Mumbles Oyster Company want to bring back a mollusc and an industry that used to be a central part of the village’s identity. Much has changed in the world since oysters were first fished off the Mumbles, and Andy is convinced that with twenty-first-century technology and thoughtful, progressive management they can make a go of it. He wants to show the rest of the world that the Native Oyster can come back from the brink.

It took a few years of paperwork for them to be granted access to a 35-hectare (90-acre) rectangle of seabed off the Mumbles pier. Once they had the go-ahead the first thing they did was to put some oysters down there.

During his surveys of the entire bay, Andy had found a handful of adult oysters and just two lonely juveniles, mini-oysters known as spat that were stuck onto other, empty shells. He needed to kick-start the oyster population.

With seed funding from the Welsh government and the EU, he bought 40,000 adult oysters from Loch Ryan in Scotland, one of the few remaining healthy,
Bonamia
-free populations of Native Oysters. Instead of being taken off to market, hundreds of bags of oysters were trucked down to the
Mumbles in batches, and during the winter 2013 to 2014 they were poured into the sea on top of the derelict oyster beds.

That winter turned out to be long, harsh and lashed by wild storms that left Andy anxious about his oysters down beneath the waves. So it was with a massive sigh of relief that, come the spring, when he returned to the oyster beds, he found a good number of the transplanted oysters had survived. The team had shown that Native Oysters can still live in Swansea Bay.

As I looked out from the end of Mumbles pier into the murky water I pondered the next and most important question. Are the transplanted oysters happy and healthy enough down there to start making more of themselves?