The Crane Valley Partnership
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Posted by Ilse Steyl Posted on 2016-08-30

Sampling Gammarus  for fish parasites

The Environment Agency (EA) has launched a project to establish the distribution of a fish parasite that uses the freshwater shrimp Gammarus pulex  as an intermediate host. The parasite of interested is a spiny-headed worm called Pomphorynchus. It causes the shrimp Gammarus pulex  to develop either single or multiple orange spots in the body, like those in the picture below. These spots increase the chances of the shrimp being eaten by a fish, completing the life cycle of the parasite.

If you find any shrimps like these during your river surveys, please let the EA know. If possible, put a small number of shrimps into a small container with some wet tissue and send them to the address below. Please include the name of the river and either a grid reference or the name of the nearest town. Should you require any containers sending to you, please ask the EA.


The hope is to obtain samples of shrimps from as many rivers as possible throughout England and Wales and even a single shrimp can help provide some very useful information.

Please send samples to:
Hannah Bradley
Environment Agency, National Fisheries Laboratory
Bromholme Lane
PE28 4NE

If you have any queries or would like more information about this project, please contact:

This information can also be downloaded as a PDF.