Endangered native mussels with a low libido are surging back after being successfully sexed-up in a project to boost numbers.
An orgy of reproduction among 70 fresh water pearl mussels taken from Welsh rivers have seen the population explode to 70,000.
Experts feared the highly endangered species was heading for extinction as reproduction stood still and its population aged.
River pollution, dredging and poaching had had a catastrophic effect on the notoriously celibate fresh water molluscs.
But intervention by the Environment Agency has reversed a potentially terminal decline.
The agency has seen a surge in the number of juvenile mussels created at its Mawddach Hatchery in Wales.
Historically they have always been linked to Queen Elizabeth I who appears in many portraits adorned with freshwater pearls.
"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.
He said as one of England and Wales' oldest river species it used to be found packed together in dense beds - reproducing through a sort of 'group sex'.
But a massive decline in numbers left many surviving specimens 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 the Environment Agency's pearl mussel specialist Anne Lewis.
"The other 21 rivers have ageing adult specimens that are often isolated geographically and no younger mussels are being recruited. Freshwater mussels can live to be 100 years old, so there is time to save the species from extinction in England and Wales." ..SUPL: