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Last Updated: Sunday, 8 October 2006, 11:58 GMT 12:58 UK
Sex-shy molluscs take the plunge
Mature freshwater pearl mussels
Those mussels who do survive can reach 100 years old
A modest mollusc has delighted experts by rediscovering the joy of sex in north Wales waters, easing fears that it is heading for extinction.

The freshwater pearl mussel has long been in decline, and is on the critical list as an endangered species.

But now 70,000 juveniles have emerged from 70 mature mussels saved from lonely isolation in Welsh rivers.

It is hoped many of the youngsters nurtured at the Mawddach Hatchery in Gwynedd will survive to adulthood.

The Environment Agency described the freshwater pearl mussel as "notoriously celibate".

We are lucky that freshwater pearl mussels can live to be 100 years old, so there is time for us to save the species from extinction in England and Wales
Anne Lewis, Environment Agency
Of those which do hatch, only a tiny percentage live beyond their early days. But those who do can make it to 100 years old.

But now agency fisheries officers have played Cupid by uniting some of the last of the breed in Wales at the hatchery near Barmouth.

"From 70 mature freshwater pearl mussels we saved from isolation in Welsh rivers around 70,000 juveniles have emerged," said Environment Agency hatchery manager Keith Scriven.

"We're excited about the success we've had with the breeding programme so far.

"While millions of larvae were successfully fertilised 12 months ago, we weren't sure how many would make it to the juvenile stage.

"At the moment the mussels are still tiny - about three-quarters of a millimetre in size.

Juvenile pearl mussels
Females are sexually mature by the age of 12
Males release sperm into water, which is absorbed by females
Each year females produce 3m glochidia, which are microscopic larvae developed from fertilised eggs
Only one in 10,000 glochidia survive, but those that do are carried back upstream on the gills of young fish

"They'll stay in captivity for another four years until they reach around one inch in length.

"Then we hope to be introducing tens of thousands of freshwater pearl mussels back into Welsh rivers by the end of the decade."

Virgin Queen

The mollusc is one of the oldest river species in the UK, and freshwater pearls can be seen on many portraits of Queen Elizabeth I, who reigned from 1558 to 1603.

Fortunately for the survival of the species, the Welsh mussel seems to have moved away from the celibacy of the "Virgin Queen".

Pollution, dredging and poaching have led to a big fall in numbers. They used to be packed together on river beds, but the agency said many now lived "alone in empty beds enduring a non-existent sex life".

"While pearl mussels can be found in small numbers in 22 rivers in England and Wales, they are only reproducing successfully in one of them," said Anne Lewis, the agency's pearl mussel specialist.

"The other 21 rivers have ageing adult specimens that are often isolated geographically and no younger mussels are being recruited.

"We are lucky that freshwater pearl mussels can live to be 100 years old, so there is time for us to save the species from extinction in England and Wales."

However, there is a long road ahead, with 95% of juveniles dying in the 10-12 years before they become sexually mature.

"So even if they are able to successfully negotiate their five-year infancy in captivity, the mussels must still survive the same obstacles that face their wild forebears once we relocate them into their natural environment," said Ms Lewis.

"But for now, our goal is ensuring this quality programme stays in place in the years to come so these juveniles and the generations of freshwater pearl mussels to follow survive to maturity and hopefully breed naturally in the wild."

Funding to save rare pearl mussel
12 Apr 06 |  Northern Ireland


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