Diving for pearl

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A rarity of nature prized for its soft-glowing beauty, the pearl has long been a symbol of the sea’s bounty. Plucked by chance and good fortune from the fleshy folds of the humble oyster the discovery of a perfect, naturally formed pearl carried with it the prospect of enormous wealth for the finder.

The result of a naturally occurring biological process, pearls are formed when certain varieties of marine molluscs attempt to reduce the irritation caused by small foreign particles that inadvertently become embedded in the meaty flesh contained within the two halves of their shell. Continually secreting smooth layers of nacre, (the same iridescent, mother-of-pearl substance that forms the shell’s inner lining) around this nucleus, the result is often a blemished, misshapen and worthless object. And of all of those molluscs – mussels, clams and oysters – capable of growing a pearl, only a very few species of oyster ever produce quality gems of commercial worth.

Standard Dress Diver
How It Was
Prior to the introduction of cultured pearls, (a comparatively recent development in which man intervenes in the natural process by inserting a small nucleus into the body of the oyster around which, it is hoped, a pearl will then form in the usual way) pearling was already an ancient industry with a long tradition spanning many cultures.

Originally harvested for the shell itself and its functional ability to be crafted into fishhooks and tools, certain types of shell became valued for the lustre and thickness of their rich mother-of-pearl lining. Fashioned into buttons, ornaments, or used as an inlay to enhance timber furniture, the same large, thick shells also produced gem quality pearls; an added bonus for those fortunate enough to discover one.

Found in commercially viable quantities in the warm, nutrient rich waters of the eastern South Pacific – in particular the archipelago of 118 islands and atolls formed from the peaks of dormant sub-sea volcanoes and centred on the island of Tahiti, in French Polynesia, and the north-west coast of Australia, around Broome – harvesting oyster shell for export was hard and precarious work.

Quickly depleting the easily accessed oyster beds, the search for shell continued into ever-deeper waters. With a natural affinity for the sea and employing the same breath-holding techniques used by pearl divers in other parts of the world, Polynesian divers would regularly plummet down as deep as 30-metres to seek out the precious shell.

With nothing other than a rope tied around their waists, a knife with which to prise the oysters loose and a deep lungful of air to sustain them, they would launch themselves into the water from small boats. Lacking goggles or masks that would enable them to see clearly while under the water, and often clutching heavy rocks to aid their rapid descent, they would gather as many shells as they could before swimming back to the surface with their small haul; a process that, with only a brief rest between dives, would be repeated time and again throughout the course of the day.

A form of pearl diving that is still continued today in certain parts of the world, breath hold diving for shell is intensive, physically demanding and not terribly efficient work; a problem that, during the latter part of the 19th century, was partially redressed with the introduction of heavy-duty diving helmets and dress.

Now able to spend extended periods of time underwater at greater depths than was ever possible on a single lungful of air – and able to gather shell in greater quantities – the chance of discovering a pearl was still limited by the fact that only one out of every 15,000 to 20,000 oyster shells ever yielded a treasure; and of those that did, many were blemished or imperfectly shaped. Nor was the use of the new technology without risk. Romanticised in fiction, the pearl shell diver’s job was one of constant hardship and danger.

Encased in a thick canvas suit and wearing heavy boots, brass helmet, corselet and lead weights that, in total, weighed more than 180 lbs, divers were dependent on air supplied to them from the surface. As well as an attendant to manage the air hoses and lifeline, up to four people at a time might be engaged in turning the wheels of the large hand pump that delivered air to the diver in sufficient quantity to counter the enormous pressure of water surrounding him at his working depth.

Reliant on an umbilical hose to the surface and with communications limited to a coded system of simple pulls and tugs on the lifeline, these early divers exercised extreme care in ensuring that their air hose didn’t become fouled or sliced on sharp undersea objects. Should the air supply fail for any reason then the water pressure would easily crush the flexible suit and, until the advent of the non-return valve, force the diver’s body up into the rigid helmet to a gruesome death.

Added to this were the natural hazards posed by sharks and venomous marine creatures. Often exaggerated out of all proportion by the divers themselves, the risks were nevertheless real. Far more insidious and less well understood, however, was the danger of spending too long at depth while breathing air under pressure. Lacking our present understanding of the causes of decompression sickness and the need to ascend slowly back to the surface in order for the excess nitrogen absorbed by the body’s tissues to escape naturally via the lungs, countless numbers of divers suffered the excruciating agony of, ‘the bends’, a condition that killed many while leaving others permanently paralysed or crippled.

With little or no formal training in the use of the equipment, these highly paid, “hard-hat”, divers were the expendable elite of an industry that, following the Second World War, entered into swift decline as cheaply produced plastics superseded the use of mother-of-pearl.

A Bit of ‘Culture’
With the cost of diving for naturally formed pearls proving uneconomic, the introduction of cultured pearl farms into Australia and Tahiti – during the mid-fifties and ‘sixties respectively – presented a new generation of divers with fresh employment opportunities.

While methods vary between Australian and Tahitian cultured pearl farms – mainly in the types of oysters used and the methods for gathering them – the essential principles remain the same. The young pearl-producing oysters are reared in holding pens where, contained in wire-framed net panels attached to long underwater lines, they are kept clean and free from algae and other encrustations. When they reach maturity a small spherical nucleus made from the shells of Mississippi mussels together with a piece of mantle tissue is surgically implanted into the oyster. The frame is then returned to the sea. Some months later, the oysters are X-rayed to determine whether a pearl is forming, or whether the oyster has rejected the implant, in which case another attempt can be made to operate on the oyster.

A trade designation reserved exclusively for cultured pearls obtained from the pinctada margaritifera oyster reared in the pearl farms that are now established in the island lagoons of the Tuamotu-Gambier Archipelago, a ‘Tahiti Cultured Pearl’ is formed over the course of several years, after which it is carefully removed and the oyster returned to the lagoon to recuperate. With a life span measuring thirty years, each oyster is capable of producing several pearls. Although sounding a simple enough process only thirty out of every one hundred nucleated oysters will produce a pearl; and of those only a mere one or two will make the grade as perfect gems deemed suitable for sale on the international market.

While divers are employed in a variety of pearl farming tasks, none is more demanding than that of harvesting young oysters from the wild for use in the Australian pearl farms.

A seasonal activity that usually takes place off of Western Australia’s north west coast between February and July, when the wind and weather patterns offer calm sea conditions, today’s pearl divers are well-trained professionals employing techniques and equipment undreamed of by their predecessors.

Going to sea for up to ten days aboard well-appointed vessels equipped with modern navigation aids, (including G.P.S. that allows them to accurately pin-point and return to areas rich in silver-lipped pearl oysters), as many as six divers at a time may be employed in gathering shell.

Equipped with wet-suits, fins, mask and an umbilical hose up to 100-metres in length supplied with air from a surface compressor, each diver works from a heavily-weighted individual down line suspended from the vessels booms and lowered to a point just above the seafloor. Attached to and trailing behind each weight is a 35-metre swim-line that the diver holds in one hand.

Towed at a walking pace across the oyster beds and able to swim from side to side and backwards and forwards along the swim-line, the diver’s other hand is free to pluck young pearl shells from the sea floor and place them in a small net bag slung around the neck. Periodically emptied into a larger bag attached to the down-line, the pearl shells are raised and sorted on the vessel’s deck.

Scrubbed and cleaned of any encrustations, those oysters deemed suitable for pearl cultivation are placed in wire-framed net panels to protect them from predators. Attached to long lines they are then lowered back into the sea in select holding areas to await the implant and grafting operation.

Although attached to the vessel by both the down-line and the air hose trailing from the boom behind the vessel, nothing is left to chance. Each diver also carries an air cylinder for use in an emergency situation. Working continually throughout the daylight hours and with each dive lasting for up to 45-minutes – sometimes at considerable depth – the greatest risk that divers face is that of decompression sickness.

Pioneering the use of oxygen to accelerate the decompression process, every ascent to the surface is preceded by a halt at 6-metres. Swapping their air regulator for one supplied by oxygen cylinders carried on the boat’s deck for just this purpose, divers spend a set period of time breathing pure oxygen while their bodies adjust to the changes in pressure.

Despite a greater emphasis on safety than was ever enjoyed by their helmeted predecessors, the inherent dangers of diving for pearl remain the same. Often working by touch in poor visibility, there’s the constant risk of inadvertently coming into contact with stingrays, venomous sea snakes, or – as happened to one unfortunate pearl diver in recent times – being savaged and killed by a marauding tiger shark.

Whether it hails from Tahiti, Australia, or elsewhere, each cultured pearl remains a miracle of nature containing within its layers stories of romance, adventure and hardship, and a little of the lives of those men – and women – who dive for pearl.

—ENDS—

The above story was first published in ‘Solitaire’ magazine in October 2002.



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