Billy Weir MSci Environmental Science joins us again for his episode, this time on his Masters research project "Assessing the impact of Eurasian Beaver (Castor fiber) reintroduction on fish populations in Plymouth, England".

Abstract - Rewilding has become an aim for conservation across the globe, and a crucial aspect of that is species reintroductions. Ecosystem engineers such as Eurasian Beavers (Castor fiber) are an excellent example of a species that can return to nature-deprived countries, such as the UK, and increase biodiversity and provide ecosystem services. The return of Eurasian beavers across Europe and the UK represents a conservation success story, despite some controversies surrounding localised flooding. 

This study investigated the impact Eurasian Beavers have on fish populations at a reintroduction project at Poole Farm, Plymouth, England. Seine netting sampling was conducted and eDNA samples were collected across three sites at Poole Farm. This data was compared to a fish population survey that occurred in October 2021 and supplemented with land imagery of the enclosure to assess beaver impact. 

The data suggests that Three-spined stickleback (Gasterosteus aculeatus) dominate the stream at all sites, and that the beaver dam provides Brown trout (Salmo trutta) with a large obstacle that they cannot pass to upstream areas, despite other literature finding otherwise. 

We suggest it’s crucial to continue monitoring the fish population at Poole Farm, and at beaver reintroduction projects across the country, as beavers become more established.

Episode guest: Billy Weir MSci Environmental Science

Episode host: Prof Simon Kemp

Episode producer and editor: Libby Kale