Matchmaking pays off for Tyne mussels

A SEVEN-YEAR drive to improve the love life of middle-aged mussels has finally succeeded.

Ecologist Anne Lewis with a pearl mussel

A SEVEN-YEAR drive to improve the love life of middle-aged mussels has finally succeeded.

The Environment Agency’s matchmaking efforts have paid off as Tyne freshwater pearl mussels are at last breeding at Kielder hatchery in Northumberland.

The North Tyne is one of the last few strongholds in England for the beleaguered species but their increasingly empty beds are making it difficult for them to reproduce in the wild.

Baby mussels largely stopped appearing in the 1960s not only in the North East but across the rest of the country and Western Europe.

That has meant a population of increasingly senior mussel citizens, with the bulk of the 12,000 shellfish in Northumberland in the 40 to 80 years old bracket. They can live for up to 120 years.

As the population thins out because there are so few youngsters, the remaining adult shellfish are becoming more widely spaced.

And as the mussel has only one foot mainly used for anchoring itself to the river bed, limiting movement, the creatures find it increasingly difficult to get it together.

Theories for the breeding slump in the 1960s include the enrichment of rivers by run-off of fertiliser from fields and also silt from drainage and more intensive ploughing.

The mussel larvae lodge in the gills of young salmon for several months and then drop away to sink into the sand where they remain for 15 years, growing to thumbnail size.

At that stage they rise to the surface of riverbed gravel to feed. It is believed that increasing levels of silt were killing the youngsters.

Agency biodiversity team leader Jim Heslop said of the long-awaited captive breeding success: “This is a turning point for the pearl mussel in the North East.

“We now have thousands of larvae which will eventually become young mussels and help to turn round the fortunes of the North East population.”

The breeding programme mirrors what should happen in the wild, using trout as host fish for the mussels.

Jim and his team used 6,000 baby sea trout to act as hosts, and as a result 25% are carrying larvae which is around a tenth of a millimetre in size.

The larvae and their host fish are likely to leave their temporary home at the Kielder Salmon Centre this week and be rehomed in the River Rede in Northumberland.

Agency ecologist Anne Lewis said: “We have worked hard with our partners, the Tyne Rivers Trust, to improve the habitat in the Rede and the North Tyne in preparation for the pearl mussels.

“In the past, pollution, dredging and poaching have all taken their toll on the population nationally but our rivers are now the healthiest they have been for 20 years. The work we are doing to improve habitat for pearl mussel is also great for other wildlife of our rivers, such as salmon and trout.”

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