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13 November 2014

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You are in: Cumbria > Nature > Nature features > The oysters of Walney

Algae growing in tanks at Walney Oyster Farm

Algae growing at Walney Oyster Farm

The oysters of Walney

Enjoyed by pop stars and aristocracy, there's a good chance if an oyster's eaten in the UK it started its days on Walney ...

Oyster Facts

The name oyster is used for a number of different groups of mollusks which grow mostly in marine or brackish water.

A team of American and Italian researchers found bivalve molluscs to be rich in amino acids that trigger increased levels of sex hormones. Their aphrodisiac reputation may  also be due to their high zinc content.

Oysters breathe like fish using gills and mantle. They have a three-chambered heart.

A single female oyster can produce up to 100 million eggs annually

All oysters produce pearls but those from edible oysters have no market value. Natural pearls from Pearl Oysters are very rare and a necklace can easily costs hundreds of thousands of dollars

It's been a roller coaster ride for the poor oyster. The molluscs have been the subject of mystery and intrigue for centuries.

William Shakespeare wrote about them, as did John Steinbeck. In fact many oyster myths remain today, some rooted in scientific fact, others pure misconception.

"Why, when the world is mine oyster, which I with sword will conquer. "

William Shakepeare - The Merry Wives of Windsor

In Roman times they were a delicacy, by the Medieval era a staple food for everyone, and by the time Queen Victoria came to the throne they were considered a dirty food suitable only for the very poor.  Today they're again a delicacy consumed by the rich and the famous.

Around 100 million of them a year start life at the Seasalter Shellfish Company on Walney Island. An oyster farm built on the site of an old gravel works on the island.

The now empty gravel pits have left behind a unique set of seawater ponds that give the farm the look of a lunar landscape.

The farm has 20 parent oysters imported from Japan. These super fertile mums and dads can be spawned every two weeks to produce their hundred million babies.


It's not a case of amorous oysters getting frisky. It's a lot more scientific than you might think.

The farm uses heat shock treatment. It doesn't sound pleasant but it works. The parent oysters are warmed up and cooled down, warmed up and cooled down which stimulates spawning.

Once that's done the males and females are separated and the eggs and sperm collected.

Then the eggs and sperm are mixed and fertilised and the larvae are put into a seawater and algae warm soup.

Seasalter Shellfish Company on Walney

Seasalter Shellfish Company on Walney

Each day a sample of the larvae mix is put under a microscope and each and every one of the tenth of a millimetre long larvae is counted. 

Over the next year or so the oyster spats are moved through the farm's heated tanks until they are tough enough to go outside.


The oysters are regularly graded on a mesh grader. The smaller ones stay in the warm and the bigger ones are cooled and put outside on the raft and pond system. Once they reach 10 mm they are driven over the marsh to the farms private beach.

Here they're tied up with rubber bands to stop them being swept away and on the windswept surf of South Cumbria they continue to grow.

At around eighteen months old they are collected and shipped as far afield as South Africa.

From the wilds of Walney to dinner plates around the globe.

last updated: 08/07/2009 at 15:25
created: 15/03/2007

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