The funders of this report should be acknowledged here. These are understood to be: The Angling Trust The River Otter Fisheries Association South West Rivers Association Game and Wildlife Conservation Trust Salmon and Trout Conservation Atlantic Salmon Trust REVIEW OF EVIDENCE OF INTERACTIONS BETWEEN BEAVERS AND FISH AND FISHERIES IN ENGLAND AND Affiliation of the author to the WALES University of Hull should be stated here, unless there is some reason that this work is not considered to be an academic report. Prof. Ian G. Cowx Peer-review of Cowx (2020), Professor Richard Brazier, February, 2020. Main points 1. This report is presented as an independent review, however, no explanation is given as to how the author has maintained an objective approach, given the funders of the work. 2. No statement has been made as to how the author has avoided bias or ensured that a balanced view of the impact of beaver on fish and fisheries is presented, in the absence of peer review of the report. 3. Throughout the document, the author violates the basic rules of writing a systematic review: (a) Opinions are regularly presented as fact, with no reference to the peer-reviewed literature to substantiate the views that are put forward, (b) References that are presented are highly selective to enforce negative preconceptions of beaver impacts, (c) Balanced, well-reasoned arguments are almost entirely lacking, due to a near complete absence of argument versus counter-argument (again unsupported by peer-reviewed references), (d) Poor understanding of the literature is rife, as is misinterpretation and/or disagreement with peer-reviewed literature, with no sound, scientific basis for such disagreement, (e) search terms for research papers, relevant to the topic, are inappropriate and bias the literature searchDecem towardsber 2020 negative impacts and (f) many important papers have not been read or referenced, illustrating significant gaps in the authors knowledge and demonstrating that he does not have the expertise to undertake such a review. 4. The report is overlong and repetitive and draws conclusions that are entirely unsupported by any data presented herein, or indeed any of the literature that has not been reviewed due to the above shortcomings. 5. Were this report to be submitted for publication and formally subjected to the peer-review process, it would be rejected outright. As such, it is no basis for the policy recommendations that it makes. 1 6. A detailed review of this report is included below, demonstrating major flaws and limitations throughout. References, questions that should be addressed, corrections of many factual inaccuracies and locations of biased and unsupported opinions are highlighted to help the author understand the magnitude of the task required should he choose to publish a revised version of this report for peer-review. Contents Summary ...............................................................................................................................4 Introduction ..................................................................................................................6 1.1 Context ...................................................................................................................6 1.2 About the author ...................................................................................................7 Review of beaver-fish interactions ...............................................................................9 2.1 Methodology ..........................................................................................................9 2.2 Review of beaver fisheries interactions .................................................................9 Distribution of beaver in Europe ..................................................................14 Distribution of beaver in the UK ...................................................................14 Ecology of beavers ........................................................................................16 Beaver dams .................................................................................................19 Effects of habitat modification by beaver activity ........................................20 Impacts on fish movements .........................................................................23 Cumulative effects of beaver activity on water courses and fish ................26 2.3 Ecosystem services ...............................................................................................28 2.4 Potential mitigation and management options and further R&D .......................30 Legal status ...................................................................................................31 Mitigation measures .....................................................................................31 Beaver Management Plans ...........................................................................34 Overview of the River Otter and its fisheries .............................................................37 3.1 Catchment characteristics ...................................................................................37 Flood risk .......................................................................................................38 3.2 River Otter fish and fisheries ...............................................................................39 Rod fisheries .................................................................................................39 River Otter national fisheries surveys (Source Environment Agency, National Fish Populations Database) ........................................................................................41 Review of the River Otter Beaver Trial Science and Evidence Report .......................47 4.1 Background ..........................................................................................................47 2 4.2 Beaver activity ......................................................................................................48 4.3 Fish and Fisheries Assessment .............................................................................52 Fisheries surveys ...........................................................................................52 Barriers to fish migration ..............................................................................59 Alteration of habitat .....................................................................................62 Disease ..........................................................................................................63 Mitigation measures .....................................................................................63 Attitudes to beavers .....................................................................................64 Economic characteriZation ...........................................................................65 Conflicts ........................................................................................................66 River Otter Beaver Management Strategy Framework ................................67 Conclusions and recommendations ...........................................................................71 Literature ....................................................................................................................78 6.1 ROBT documents reviewed ..................................................................................78 6.2 References............................................................................................................79 3 Summary In recent years, beavers have been reintroduced into the UK, mostly in enclosed (fenced) environments. Several ‘wild’ populations have also established, including one in the River Otter in Devon, which is being used as a trial to assess the likely impacts (positive and negative) on riverine ecosystem functioning and biodiversity. There are concerns, however, that the River Otter trial is too narrow in scope to provide robust evidence to inform decisions on further reintroductions, especially into the wild. The aims of this review are to: ñ re-examine the evidence base on the scale and intensity of impacts from beaver reintroductions on river ecosystems, and specifically on fish and fisheries; ñ review evidence from the River Otter Beaver Trial and associated studies to understand the impact of beavers on fisheries under ‘wild’ conditions; ñ provide conclusions and recommendations about the potential impact of beavers on fish and fisheries with particular reference to UK rivers. A review of the literature and other materials related to beaver reintroductions, with specific reference to fish and fisheries, was carried out. There is considerable emphasis in the literature and media on the positive benefits that beavers can bring to aquatic ecosystems and biodiversity, but the reintroduction of beavers can also cause a number of potential problems, such as disruption to fish migration and fish recruitment, damage to trees, loss of agricultural production, and damage to banks and other infrastructure, with concomitant impacts on biodiversity, stakeholder conflicts and management costs. The fish and fisheries problems mainly occur because of construction of dams that impede fish migration and flood spawning and nursery habitats. It also appears that most of the costs associated with dealing with the impacts of beavers are borne by the stakeholder, including A land/riparianbalanced summary