The reason for having oysters is that they are filter feeders. As they open and close their shells each oyster can filter 100 litres of water a day and digest edible material in the water, rendering it into edible oyster flesh and purifying the waters. .What is more, they breed, and thus the three thousand oysters from Loch Ryan will become many more; and more oysters means more filtering. It also means a renewal of the lost shellfish industry in the Humber, something much needed at a time when fisheries in Britain are under threat from over-exploitation.
Of course oysters alone are insufficient. The waters that flow from the rivers of Yorkshire and its southerly neighbour Lincolnshire were subject to water purification treatments and restrictions on the industrial pollution of water. This pollution has so blighted this isle for two hundred years and had to be stopped and reversed. The oyster beds are one later stage in a long process of repair.
The beds are carefully sited to give the oysters maximum chance to thrive, and moreover the oysters are confined to cages attached firmly to the sea bed to prevent their being swept away by the strong currents that scour the area. But their spawn will flow free out through the mesh of the cages, restocking the coastal area.
But oysters are not the only shellfish being introduced to the new fishery. Bouchot mussels, also filter feeders, are arriving from Brittany from near Mont Saint Michel, where they are cultivated and are known to produce a highly delicious flesh.
The cultivation technique is to stretch out a line of poles from the shore, which ropes are stretched, propylene being the favoured material. The rope are seeded with mussel spawn. At the foot of each pole there is an inverted cone to prevent crabs from climbing up to take the mussels. Harvest involves pulling the mussels off the ropes, often by machine. Further protection is given by draping netting over the mussels, which deters and prevents predators even more. Once the mussels are sown this is an easy fishery, for the mussels seed themselves every year,as long as you do not take the lot of them.
Other filter feeders being introduced are razor clams. These are commoner in West Britain than in the east. They dwell in sandy beaches and are perfectly edible. They are being introduced to the sandy beaches of Spurn Island, a south-pointing spit that was recently sundered from the mainland by a storm. It houses Britain's only full time lifeboat crew.
Humankind damaged nature and it seems that it needs to harness nature to solve the problems that neglect of nature has created. This is one small ecological step in the creation of a greener world.