Challenges in conserving critically-

endangered Freshwater Pearl Mussels;

advances over 10 years

Dr Ceri Gibson and Pearl Mussel team cgibson@fba.org.uk

www.fba.org.uk

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1. Males release sperm which is inhaled by females.

2. Embryos develop into glochidia, which are released into the water.

3. Glochidia must encounter and attach to a suitable host fish for ~10months.

4. Mussels release from gills and burrow in the sediment.

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FPM LifecycleJuly / Aug

May / June

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Habitat requirements

Pristine water qualityStable clean gravelsPedal feeding juveniles dwell in interstitial sites

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Windermere

235km2 catchment

14.76km2 Lake

40.3m above sea level

• FPM wiped out of Leven in 19th

Century• 9 records for Brathay• Over 100 Brathay juveniles in

Ark

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FBA Ark timeline

2006• Concept of an Ark at FBA

2007

• Ark installed at Mitchell Wyke

• First adult mussels arrive on 18th April

2008• First successful excystment

2009

• Filters required to manage water supply efficiently

• Funded by Natural England & Environment Agency

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• More adult mussels received

• Varying conditions / improved understanding

2015• Wider river improvement project starts

2017• Juveniles reintroduced to native rivers

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Regular cleaning / observation of tanks and trays

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Manipulating host fish

Essential to prevent salmon from smolting before glochidia excyst

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Windermere Reed beds

1902

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Windermere Reedbeds

1980

2001

Grassholme Island

Declining reed beds indicate changing water quality

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Windermere Surface Temperature –anomalies from 1961-90 mean

Period used to calculate IPCC mean

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First reintroduction - Still learning

Importance of local currents and sheer stress

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First reintroduction - Still learning

7cm

Herculean effort upstream and vertically up. Why?

Conclusions after 10 years

FBA breeding programme has shown considerable success

Improved understanding of the Ark system and mussels

Identification of suitable species of host fish

Application of WFD status is not ambitious enough for pearl

mussels

CEN standard agreed across 28 European countries which

underwrites the quality of water environment required for

protection of and successful reproduction of FPM

Currently we have not found any ideal sites for pearl mussel

reintroductions in the rivers examined

Engagement with all parts of the community is invaluable

Managing research and landscape-scale improvement with

annualised funding is a challenge!

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www.fba.org.uk

Thank you for listening

Any Questions?