The experts at University Centre Sparsholt (UCS) are in the headlines again with the news that fisheries lecturer Dr Josie Pegg’s research has been published in the International Journal for Parasitology. The collaborative research, led by Salma Sana from Bournemouth University, the Environment Agency and the Centre for Environment, Fisheries, and Aquaculture Science (CEFAS), looked into the genetics and presence of a non-native parasite in British waters.

The project studied the parasite Sphaerothecum destruens, commonly called ‘rosette agent’, which is of concern as it has been shown to be severely harmful to salmonids in Canada and native cyprinid species in continental Europe. The parasite has been brought to the UK with a non-native invasive fish species – the topmouth gudgeon (Pseudorasbora parva).

In this paper Josie and the team looked at two aspects of the parasite – firstly how genetically diverse it was in the UK, and secondly could they detect it in water samples using environmental DNA (eDNA). eDNA is the DNA shed by all living organisms, through excretion, shed skin or mucus. It is currently attracting much interest within the scientific community with its potential to greatly aid the detection of rare or invasive aquatic species.

The study found that the genetics indicated the parasite was likely introduced to the UK more than once – this is important as understanding introduction routes helps us plan to protect native fish stocks. They also found eDNA was an effective method of detecting the parasite in water bodies – an exciting development representing a positive test of this novel technology in detecting disease in aquatic systems.

Finally, Salma, Josie and the team showed that rosette agent may be present in a system even if its host, topmouth gudgeon, has been eradicated. The importance of this finding is that it shows the parasite is able to spread to native fish populations and persist. On the positive side none of the fish looked at had been made ill by the parasite, but understanding how a parasite behaves helps UK fish experts prepare and prevent it causing problems as seen elsewhere.

The UK freshwater fish stocks are hugely important for ecology, food and recreation, and this project is just one of the ways the fisheries team at Sparsholt are working with academics, industry and government organisations to protect them.  UCS students learn about all the methods used in this paper as part of their FdSc and BSc fisheries and marine science degree courses.

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