Please see the notice from the Environment Agency below:

A project is underway to establish the distribution of a fish parasite that uses the freshwater shrimp Gammarus pulex as an intermediate host. The parasite we are interested in 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 above. These spots increase the chances of the shrimp being eaten by a fish, completing the life cycle of the parasite.

Please see the information sheet from the EA (link below) to see how you can help.