The sex life of elderly shellfish in the north of England needs to be spruced up if they are to survive, scientists say.
The Environment Agency says freshwater pearl mussels, which thrive in Northumberland and Cumbria, are at risk of extinction because their sex life is not what it should be.
Scientists say the youngest mussels are middle-aged, but their numbers are dropping and thousands are living solitary lives in empty beds.
Now ways of saving the declining populations are being investigated by the Agency and English Nature.
The are about 12,000 of the shellfish in Northumberland alone.
Among the ideas is a plan to relocate isolated individuals and help them socialise.
The UK's leading experts representing government, national parks and wildlife trusts are discussing the problem.
Newcastle-based conservation officers of the Environment Agency said: "We have a responsibility
to protect this species as part of the UK Biodiversity Action Plan - a strategy to conserve, enhance and work with nature and ecosystems rather than against
"Conservation bodies have reached a point where some very hard decisions need to be made.
"We can't just monitor these populations until they become extinct. We need to take active measures to prolong their existence.
"This is a rare species that is under threat around the world, not just here. To lose it would be a tragedy."
David Fraser of English Nature said: "We don't fully know why freshwater pearl mussels are not breeding but illegal pearl fishing and reduced water quality are probably important factors."