Freshwater Pearl Mussel Glochidia Found in SW Scotland!


31st Oct 2019
by Beth de Lacy

Last week GFT were out electrofishing on a tributary of the River Bladnoch surveying four different sites.

The photograph shows glochidia on the gills of a trout parr.
The photograph shows glochidia on the gills of a trout parr.

The burn is known to have one of the last remaining populations of freshwater pearl mussels (Margaritifera margaritifera) in South West Scotland.

The survey was to check salmon and trout numbers and to check for the presence of mussel glochidia on the parr.  It is exciting to be able to report finding glochidia on the gills of trout parr. Glochidia are the larvae of freshwater pearl mussels which are released through summer and attach themselves onto the gills of passing salmonid parr. This is a great sign as it suggests that the pearl mussels are reproducing.

It is thought that certain temperatures cause female freshwater pearl mussels to release up to 4 million glochidia, most of which will perish. A small number however, will successfully attach onto passing parr and stay there until the following summer where they then drop off into the river bed and continue to develop. Freshwater pearl mussels can live to be over 100 years old making them one of the longest-lived invertebrates. They have been subject to a large amount of poaching across Scotland over many years making them now highly protected. It was great news finding glochidia in some of the trout and salmon parr!

 

Further Information

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VACANCY AT GALLOWAY FISHERIES TRUST (SIX MONTH INTERN POST)

An internship is available from late August 2020 until late February 2021 (26 weeks) to work with Galloway Fisheries Trust biologists on a range of projects.

VACANCY AT GALLOWAY FISHERIES TRUST (FULL TIME PERMANENT POST)

Galloway Fisheries Trust is looking to recruit a new Fisheries Biologist to join our team. The successful candidate will have the opportunity to take a lead role in many of the GFT research, monitoring and restoration programmes. This is a full time permanent post.

Biodiversity Challenge Fund Habitat Restoration Project

The aims of this project are to improve both instream and riparian habitats for both salmonids and freshwater pearl mussels; freshwater pearl mussels are now a critically endangered species and there are very few known populations remaining in Scotland.

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