Beaver Translocation Consultation - River Spey Catchment Environmental Report

Published: 2023 

1. Background

An update to the Beavers in Scotland Strategic Environmental Assessment (SEA) produced in 2017 was published in 2022 as an Environmental Report Addendum 2022 (ER). The ER brings up to date to our knowledge of beavers in Scotland, their impacts and management since the 2017 report. The ER Addendum supports the new policy position announced by Scottish Ministers in November 2021 to enable the proactive movement of beavers to new areas of Scotland and the publication of Scotland’s Beaver Strategy. It provides a national overview of the environmental effects that are likely to be important in informing where beaver translocation benefits are likely to out-weigh the risks. Socio-economic impacts are not part of the SEA process, but socio-economic costs and benefits are also recognised.

NatureScot have set out that we will assess the effects of beaver releases into new areas at a catchment scale. The assessment of catchments will be subject to prioritisation based on their suitability for beavers and other factors including where there is an interest in beaver translocations. The River Spey catchment has been selected for assessment because it is the highest ranking river catchment in Scotland in terms of the extent of suitable beaver habitat. In addition, there is expressed interest in beaver translocation to the Cairngorms National Park. The purpose of this environmental report is to assess the risk and benefits that are particularly pertinent to this catchment rather than to review the entire range of potential effects that have been assessed previously. A Habitats Regulations Appraisal (HRA) of the potential effects on European sites (Special Protection Areas (SPAs) and Special Areas of Conservation (SACs)) has been carried out and the conclusions will be published separately.  Licences to allow beaver translocations to the River Spey catchment can only be granted if it can be concluded that the proposals will not adversely affect the integrity of a European site.

Ecologically the river catchment (with suitable habitat) is the logical extent that beavers will disperse to in the medium-long term if released into a particular catchment. Hence NatureScot have proposed to assess the environmental effects of beaver translocations at the scale of main river catchments. A previous analysis of catchment permeability (Stringer et al., 2015) suggests most catchments are likely to be permeable to beaver dispersal, i.e. there will be movement between catchments. This analysis indicated that 34.8% of the catchment boundary for the Spey catchment is likely to be permeable to beaver movement to adjacent catchments. This analysis did not account for colonisation of freshwater via coastal routes. (The model applied a cost distance from watercourses up to a maximum of 300m, with overland movements limited by urban areas and steep ground.) The River Spey catchment has potential linkage to the Spey Coastal, Lossie, Findhorn, Lochy, Tay, Dee, Don and Deveron catchments via watersheds. We have not included these other main catchments in the current assessment. Instead, we plan to make assessments on a catchment by catchment basis and will assess the need for impacts in other catchments to also be assessed as the beaver range expands.

The proposed approach does not incorporate any population modelling to assess the likely time taken to colonise different parts of the catchment, but assumes that all areas that are ecologically accessible thus could be colonised by beavers in due course and aims to assess the likelihood and significance of effects. However, population modelling tools are now available that allow such projections to be made and we explore this in section 1.1 below.

The catchment boundary is illustrated in Figure 1.

1.1 Beaver presence and predicting their spread

Parts of the river Spey catchment have long been identified as being one of, if not the most suitable location for beaver releases in terms of the species requirements (MacDonald et al. 1997, Webb et al. 1997).  There are currently no wild beavers in the River Spey catchment. A study commissioned by the Cairngorms National Park Authority and published in April 2022 on the potential for natural colonisation into the Park and habitat suitability found that the potential for natural dispersal from existing wild living beaver populations in Scotland (mainly Tayside) was quite low given the presence of physical barriers such as dams, hydro schemes and challenging terrain. Hence any decision to allow the translocation of beavers will dictate the speed of colonisation. A strategic approach to translocation brings the additional benefit of providing the opportunity for a larger initial founder population, with greater genetic diversity.

The CNPA has a published 2019-2024 Cairngorms Action Plan setting out the six big steps for nature recovery. Beaver are included as a priority species alongside ambitions to restore freshwater habitats on a landscape scale. The Board of the CNPA approved the decision to lead on beaver reintroduction to the National Park following the commissioned study referred to above.

Using a population modelling tool produced by the University of Newcastle in partnership with NatureScot we can try to predict the likely growth of a beaver population following a wild release. We can run the model   based on different release scenarios to examine the differences depending on the size and composition of the founder population, the locations and suitability of the release sites.

The model works by simulating beaver population growth based on a range of known life history parameters (breeding and recruitment, survival, territories (size and features) within a landscape of three habitat suitability classes (informed by habitat mapping); ‘suitable’ to support territories, ‘dispersal’ habitat and ‘unsuitable’ habitat.

Here we have provided the outputs from model simulations based on the release of 5 and 10 family groups in the upper catchment. Both indicate relatively modest rates of population spread from the release sites, with the predicted occupancy after 10 years shown in Figure 3 (a and b).  Both starting populations suggest a strong probability of population persistence and growth.

Table 1. Results of simulations of population growth after 10 years with five initial groups of beavers

year after release	number of families average (min-max)	number of families median	predicted probability of at least 5 families	predicted probability of number of territories having at least doubled	number of adults average (min-max)	number of adults median	predicted probability of at least 9 adults	predicted probability of abundance having at least doubled
1	8.3(6-10)	8	13%	0%	12.2(10-14)	12	13%	0%
2	10.9(8-14)	11	67%	0%	15.3(10-19)	15	67%	0%
3	12.9(7-19)	13	80%	0%	17.7(9-23)	19	80%	0%
4	14.1(8-20)	14	80%	7%	19.1(11-26)	19	87%	0%
5	16.2(10-23)	16	100%	20%	21.7(12-32)	21	93%	13%
6	16.1(10-24)	15	100%	20%	22.6(13-38)	23	93%	20%
7	16.6(8-23)	16	93%	33%	24.8(10-37)	26	93%	33%
8	16.3(9-23)	16	93%	33%	25.3(12-40)	25	93%	40%
9	17.2(9-26)	18	87%	27%	28.7(11-47)	27	87%	47%
10	18.3(9-27)	19	87%	27%	31.3(11-48)	32	93%	53%

*Summary values include 15 simulations considering similar initial territories.

Table 2. Results of simulations of population growth after 10 years with 10 initial groups of beavers

year after release	number of families average (min-max)	number of families median	predicted probability of at least 20 families	predicted probability of number of territories having at least doubled	number of adults average (min-max)	number of adults median	predicted probability of at least 29 adults	predicted probability of abundance having at least doubled
1	17.7(15-20)	18	13%	0%	25.9(22-29)	26	20%	0%
2	21.3(16-27)	22	73%	0%	31.4(23-39)	31	80%	0%
3	23.7(16-32)	23	87%	0%	34.3(24-48)	34	80%	0%
4	26.2(20-32)	26	100%	0%	37.4(27-50)	36	87%	0%
5	26.9(19-39)	26	93%	0%	38.1(28-57)	37	93%	0%
6	28(20-39)	27	100%	0%	42.2(29-70)	41	100%	7%
7	30.1(22-44)	30	100%	13%	45.7(34-78)	42	100%	13%
8	30.8(22-44)	30	100%	20%	47.7(30-76)	44	100%	13%
9	31.2(21-48)	30	100%	13%	51.7(28-101)	49	93%	27%
10	31.5(22-51)	29	100%	13%	56.3(28-117)	51	93%	27%

*Summary values include 15 simulations considering similar initial territories.

a)

b)

The modelling tool is a simplification of reality and makes assumptions about habitat suitability based on the habitat classes assigned and does not account for barriers to movement such as dams. The underlying beaver habitat suitability layer (Potential Core Beaver Woodland) is designed to be relatively conservative, highlighting better quality habitat – but it is likely beaver territories may be established in poorer quality habitat, especially in the longer term. These types of factors will be incorporated into improved versions of the modelling tool. Predicted population changes over time and space will also vary depending on the specific details fed into the modelling tool, such as the precise location of releases, and beaver family structures. However, it provides a useful basis to explore predicted beaver occupancy in the Spey catchment and about the potential rate of spread based of different modelled founder populations.

The long-term monitoring of the beaver population is an action in Scotland’s Beaver Strategy 2022-2045. Post-release monitoring of a beaver population is likely to be a condition of a licence to allow the release of beavers into new catchments.

2. Environmental characteristics of the River Spey catchment

General description of the catchment

The River Spey is the second longest river in Scotland, with a catchment area of over 3,000 km², of which the main river comprises 170 km (105 miles). The catchment falls between two Local Authority administrations, the Highland and Moray Councils. Two thirds (67%) of the catchment falls within the Cairngorms National Park and just over half (53%) of the National Park area lies within the River Spey catchment.

The catchment is divided into two main parts, the ‘upper’ catchment is taken to be the land upstream of Grantown-on-Spey and includes the major tributaries of the rivers Dulnain, Nethy, Druie, Feshie, Tromie and Truim. The lower catchment roughly aligns with Moray council’s boundary and extends from Grantown-on-Spey to Spey Bay and includes the rivers Avon, Livet and Fiddich.

A very helpful summary of the catchment characteristics is provided by the Spey Catchment Initiative website.

Outdoor tourism, agriculture, forestry, food and drink are the main economic activities within the catchment. Around 1.92 million people visit the Cairngorms National Park every year from all over the world. More than half of the visitors come from Scotland, 25% from elsewhere in the UK and 21% are international visitors from around the world. Aviemore is the main tourist destination in the National Park. Wildlife tourism occurs throughout the catchment with hubs around the RSPB reserve at Insh Marshes, Loch Garten, Glenmore, Inchriach and Invereshie, Craigellachie, Glen Feshie, Rothiemurchus, Abernethy and Spey Bay. The rivers also act as focal points for tourist with the main rivers having associated footpath networks. There are multiple sites used for water-based recreation in the catchment, with main hubs being Loch Insh and Morlich. Loch an Eilean. Loch Vaa is also popular for wild swimming. The Spey is extensively used by canoes and rafts from Loch Insh to Spey bay and the river Feshie by kayakers. The River Spey is classed as one of the premier rod fisheries in the world.

Hill farming, forestry and sporting estates dominate the land-use pattern in the upper catchment, while cattle rearing, extensive commercial forestry and arable farming become more prevalent as the valley floor widens. Fifty percent of the River Spey catchment is mountain and moorland and is used as rough grazing whereas only about 5% is used for arable agriculture. The remaining 45% of ‘intermediate ground’ between the high ground and the more sheltered valley floor presents the greatest diversity of land use. This zone is typically managed for a mixture of crofting, farming, forestry and sport. The Land Capability for Agriculture is typically 4.2 or lower (typically used for livestock grazing) in the upper catchment, with areas of Prime Agricultural Land in the Strath downstream of Charlestown of Aberlour, which is typically used for growing barley used in the distilleries.

There is 23,297 ha of land in the catchment within public ownership of which 947 ha is Potential Core Beaver Woodland. The catchment ranks3^rd nationally in terms of the extent of Potential Core Beaver Woodland in public ownership, most of which is managed by Forestry and Land Scotland. The catchment also has one of the highest proportions of designations, with nearly 3% of designated land having the potential for beavers to establish (2,414.5ha of Potential Core Beaver Woodland overlap).

Within the Spey catchment there are already changes in land use apparent with increasing tourism and access in recent years. There is a definite land use trend towards rewilding or ecosystem restoration within the Spey catchment and the Cairngorms Connect partnership in particular, is actively working on a long-term vision to drive this forward in the upper catchment.

The development of infrastructure supporting the enjoyment of nature will likely continue independent of any beaver translocations. However, the presence of beavers has the potential to bring new ecotourism opportunities from the running of beaver tours, wildlife photography operations and the multiplier effect to the local economy through support services, transport, catering and accommodation. If beaver translocation were not to go ahead there would be significant opportunities missed in terms of the ecosystem services explored in more detail in the following sections; in particular the potential for restoring rivers and wetlands and promoting natural flood management and the potential to regulate water passage through the catchment.

Potential for beavers and beaver activity

The River Spey catchment has a total watercourse length of 6,888 km and ranksfirst in Scotland in terms of the extent of potential beaver habitat with 7,085 ha of ‘Potential Core Beaver Woodland’ (ER Addendum). The Potential Core Beaver Woodland data layer is comprised of largely broadleaved woodland and scrub within 50m of freshwater edge, with a gradient of <15% in non-tidal areas. However, in addition to the ‘Potential Core Beaver Woodland’ there are also other areas of habitat that beavers may use on a more temporary basis. Over time beavers will tend to be less ‘choosy’ and select more sub-optimal habitats as catchment territories fill up.

Potential Core Beaver Woodland (MAP 1) is distributed throughout the catchment from Laggan to Spey Bay, fringing many of the lower elevation tributaries of the Spey, and Lochs Garten, Mallachie, Vaa and Loch an Eileen. The most suitable habitat for beavers is the network of lochans and wetland environments largely in the upper Spey catchment. Areas where Potential Core Beaver Woodland is notably absent are along upper sections of the main river Spey such as stretches between Kincraig and Newtonmore and Newtonmore to Laggan. The Cairngorms National Park Authority commissioned study published in April 2022 identified that 30% of the National Park (noting this not the same boundary as the Spey catchment) watercourses are highly suitable for beavers.

Not all of the catchment will be accessible to beavers as some river sections are steep and rocky with waterfalls or significant artificial barriers including hydro dams.  Figure 3 illustrates data that has been gathered on obstacles to fish passage and is publically available at https://marine.gov.scot/maps/1746  - (please refer to this interactive map for more detail of individual structures). Similarly, beavers may not be able to utilise parts of the river system, but equally they may be able to navigate a land route around some of these barriers. The Spey itself has a dam in the upper reaches and there are some dams on tributaries, notably the Tromie at Loch an t-Seilich, and the Truim just south of Dalwhinnie. There is a dam at the end of Loch Ericht. There are a few others, for example on the Allt Cuaich. Most of them are high in the catchment with little potential beaver habitat upstream hence it is questionable how much beaver would wish to pass them. There are no barriers that are likely to impede the downstream movement of beavers.

The River Spey and the main tributaries in the catchment are unlikely to be subject to beaver damming, with damming most likely on the smaller burns where there is a shallower gradient. NatureScot commissioned the University of Exeter to produce a ‘Beaver Dam Capacity’ (BDC) layer for the whole of Scotland in 2020 based on the methods of Graham et al. (2020), Graham et al. (2021). The model infers the density of dams that can be supported in stream reaches (111.1m ± 52.5) across a catchment.⁴ Each reach is classified for dam capacity using five categories ranging from ‘none’ (defined as no capacity for damming) to ‘pervasive’ (defined as having a maximum capacity of 16-40 dams in 1 km of channel) assuming the beaver population is at carrying capacity, i.e. a maximum value.

See Map 2 for the Beaver Dam Capacity (BDC) modelling outputs for the Spey catchment.

Table 3 provides a summary of the Beaver Dam Capacity modelling outputs for the Spey catchment.

Table 3 Beaver Dam Capacity model predictions for the River Spey catchment

Beaver Dam Capacity class	Length of watercourse in catchment (km)
None	904.6
Rare	3649.1
Occasional	1118.9
Frequent	631.3
Pervasive	583.6

Were beavers at their maximum capacity, 18% of the total watercourse length is predicted to be liable to ‘frequent’ or ‘pervasive’ damming. Whilst the Spey is one of the longest watercourses in Scotland (ranked 3^rd) the length of watercourse that is predicted to be subject to damming (occasional to pervasive) as a ratio of total watercourse length it is just over a third (34%).

 

3. Key environmental issues to consider in the River Spey catchment

This section includes an assessment of the potential environmental effects (including cumulative effects) that may arise in catchments with a focus on receptors (interests) identified in the national spatial analysis (in the ER Addendum) and drawing on the 2017 ER, those effects that are considered to be the most important within each catchment. An updated review of beaver mitigation approaches is included in the 2022 ER Addendum.

3.1 Biodiversity, flora and fauna

A comprehensive assessment of biodiversity impacts is included in the ‘Beavers in Scotland’ report, which covered each major habitat type and each major taxonomic group. This emphasises that on balance beaver cumulative effects are expected to be largely positive for biodiversity. We have sought not to repeat this evidence here and hence the information presented is somewhat biased towards where there is the potential for negative effects. In highlighting these potential effects it should be noted that there are many potentially positive effects not repeated here for brevity.

An appropriate assessment (HRA) of potential effects on Natura sites (Special Protection Areas (SPAs) and Special Areas of Conservation (SACs)) has been carried out and the conclusions will be published separately.  It outlines the conclusions regarding the likely significant effects and effects on site integrity for each of the Natura sites in the catchment and the need for mitigation and management. To avoid duplication, the full assessments are not included in this Environmental Report.

The potential impacts on Sites of Special Scientific Interest (SSSIs) features (not already covered by HRA or equivalent interests) are included as Annex 1. In assessing impacts on SSSIs, we have scoped out those where beavers are unlikely to have an effect due to a lack of ecological connectivity or geographical overlap. The main feature types on which beavers are likely to impact are woodlands, marshes, fens and meadows and lochs. The hydrology of raised bog interests are likely to be independent of beaver effects. Lochs and fen features are most likely to benefit from beaver presence through improvements to water quality. The introduction of/or release into the site of any wild, feral or domestic animal, plant or seed is an Operation Requiring Consent (ORC) for many of the SSSIs. 

The biodiversity text below also includes notable conservation interests in this catchment in the wider countryside.

Riparian woodlands

As discussed in Section 2. The Spey catchment has the highest area of Potential Core Beaver Woodland of any catchment in Scotland (7,085ha). The Cairngorms National Park Forest Strategy 2018 outlines the Authorities’ wish to strengthen and further develop a forest habitat network across the Cairngorms, including between river catchments. The National Park Authority has a target to expand the areas of woodland by 5,000ha in the next five years. The Forest Strategy provides a breakdown of total woodland cover in the National Park based on National Forest Inventory (2015) data, nineteen percent is broadleaved woodland (of which 16% is birch woodland) and of the 81% conifer, 60% is scots pine.

There are many drivers for increasing riparian woodland from improving nature networks, moderating water temperature and flood mitigation, reducing aquatic pollution and overall climate mitigation. The National Park Forest Strategy refers to the need to increase riparian woodland for the benefit of beaver and to reduce impacts of beaver as they arrive in the catchment. The Spey Catchment Initiative acknowledges that the riparian habitats face pressures such as agricultural land use (in particular livestock impacts), a historic loss of riparian tree cover and the spread of invasive non-native species alongside modification of watercourses and industrial use / abstraction. There are ongoing efforts to increase the riparian tree cover through and by reducing browsing pressure and to reinstate natural processes such as by leaving deadwood in watercourses (tributaries in the Upper Catchment).

Historical grazing pressures have contributed to a reduced complement of broadleaves, and the establishment of beavers in this catchment could present an additional pressure on riparian woodland. The analysis of Potential Core Beaver Woodland with Native Woodland Survey of Scotland data on herbivore impacts, (which is now more than 10 years old) highlights that 94% of Potential Core Beaver Woodland was classed as subject to Moderate to High herbivore impact. Mitigation of beaver impacts will likely involve managing the levels of other herbivore browsing so that woodlands experience lower levels of overall grazing impact and natural regeneration and coppice growth can occur.

Lying in the east of the country, the Spey catchment has a more continental climate and no true ‘rainforest’, however, there are still riparian woodlands and trees particularly ash, willow and hazel that have associated assemblages of rainforest lichen and bryophyte species that could be impacted by beaver activity. Given that many species of interest have specific humidity requirements, trees near to freshwater will typically have more of these assemblages. For example, Coul woods has an assemblage containing many rainforest species, and is potential beaver habitat. Where locations are known, some additional monitoring post-release of sensitive sites/ individual trees would be advised to assess beaver tree species preferences in the local context and any impacts on lichen assemblages that may warrant further consideration of mitigation. This approach was taken in Knapdale where, as a precautionary measure, a few trees that hosted a particularly rare lichen were protected. Some additional survey may be required where there is insufficient information on lichen distributions.

The Beavers in Scotland Report documents the potential benefits of beaver presence to woodland interests including increased structural diversity, light levels to the field layer, an increase in standing and fallen deadwood and an increase in the extent of wet woodland.

Aspen

Aspen is a special component of the woodland resource in the Spey catchment, having a greater proportion of aspen woodland than any other catchment in Scotland. Aspen is also highly valued because it is to host a variety of dependant species including invertebrates, lichens, bryophytes and fungi. Aspen is also a preferred species for beaver foraging and in combination with other herbivore impacts, there is a risk that stand condition or aspen specialist species will be negatively impacted. There is 197 ha of woodland with >25% aspen canopy cover (based on Native Woodland Survey of Scotland data) in the River Spey catchment. Of this, 64 ha is within Potential Core Beaver Woodland, i.e. an estimated third (33%) would be accessible to beaver foraging. Beavers are central place foragers and hence their impact on woodlands through felling and to a lesser extent flooding, can be expected to be patchy in space and over time. The CNPA Forest Strategy notes that for Aspen “Many aspen stands in the Park are over mature and have no young trees to replace them.” Beaver feeding on aspen could promote clonal regeneration by prompting coppicing and suckering. However there are some unknowns around the specific impacts of beaver on the species dependant on aspen. The dark-bordered beauty moth uses young aspen suckers and so it could be that suckers promoted by beaver felling would be suitable for its larvae, however this is dependent on wider herbivore grazing pressure (deer and domestic stock) being sufficiently low for the survival of this resource. Aspen hoverfly larvae need a constant supply of decaying bark on aspen deadwood. Thus beaver feeding on bark may locally reduce the resource although we can expect to see an increase in aspen deadwood, much of the bark is expected to be utilised. Other dependent species including a range of bryophytes and lichens need mature aspen, for example, the aspen bristle-moss Orthotrichum gymnostomum is a rare Scottish Biodiversity List priority species that grows only on mature aspen trees. Over time the proportion of mature aspen may become a reduced resource within the riparian zone close to beaver territories.

There is overlap of aspen woodland with Potential Core Beaver Woodland, as illustrated in MAP 3 throughout the middle catchment, with pronounced areas of overlap around Loch Insh and Loch Alvie.

In the absence of browsing pressure from other herbivores, aspen stands should be able to quickly recover from beaver felling, though regrowth may experience repeated coppicing. Greater resilience can be promoted by increasing the extent of aspen stands and promoting a mix of age-classes through monitoring and managing herbivore impacts. A risk-based approach could be taken to protect mature trees where this is a priority. The Cairngorms Aspen Group has been working to identify stands that are likely to be accessible to beavers and that may be at greatest risk from foraging impacts. These stands should be subject to monitoring informed by beaver presence and appropriate mitigation implemented should beaver presence pose a significant risk. This is likely to necessitate an element of tree protection from beaver impacts, either individually or of stands identified as high risk at least for a time. Otherwise there is a risk that the aspen resource accessible to beaver will become dominated by young tree growth that will not support the full range of aspen-dependent biodiversity, although it is worth noting that much of the aspen resource is not in the immediate range of likely beaver browsing.

Atlantic salmon/fish

Atlantic salmon (Salmo salar) and Sea lamprey (Petromyzon marinus) are qualifying interests of the River Spey SAC.

The reaches downstream of Aviemore provide appropriate habitats for all stages of development of the sea lamprey and these support a relatively large population at the northern limit of its British distribution. Adult sea lamprey require migration routes that are free of obstacles. Impassable man-made structures, e.g. dams and weirs, will restrict their distribution across a catchment. Natural obstacles, such as waterfalls, will do the same. Sea lamprey require clean, well oxygenated water and suitable substrates to use as spawning and nursery habitat. In the River Spey, sea lamprey have only been recorded in the main stem of the river, and at locations where beaver will not be able to dam due to the river width and power. Hence impacts would mainly relate to the influence of dams upstream in the catchment which could potentially have positive and negative effects, i.e. restricting the transport of fine sediment that could degrade spawning habitat, or influencing the distribution of coarser substrate used for spawning habitat.

Atlantic salmon numbers have declined throughout their geographic range, including in Scottish rivers. In the River Spey the salmon population has shown a decrease in the spring multi-sea winter fish since 1952. Any barriers to fish passage have important negative effects.

Salmon are known to be impacted by a range of pressures in the freshwater and marine phases of their lifecycle. In the freshwater environment these pressures may include, amongst others: over exploitation, loss of habitat connectivity, habitat degradation, climate change-related changes to surface water temperature and hydrology, built development (such as hydropower), invasive non-native species, direct and diffuse pollution, water temperature uplift from distilleries, predation and the inappropriate stocking of conspecifics.

The key benefits of beaver activity for salmonids that are commonly cited include increased habitat heterogeneity and water quality. Conversely, the principal negative consequence of beaver activity often cited is the potential for dams to impede or delay salmonid migration and the potential modification of fluvial habitats influencing the availability of spawning habitats.  However, the evidence around the potential effects on fish populations is complex and is reviewed extensively elsewhere (‘Beavers in Scotland’ see 3.4.7, CREW report). These reviews highlight the potential for positive as well as potentially negative effects. For example the variability of damming effects on migration depending on flow regimes, the spatially variable effects on temperatures, and predation risks, the beneficial effects of an increase in woody debris and for sediments, water quality and invertebrate populations.

The River Spey catchment has a watercourse length of 6,888km. Of this extent there is predicted to be an overlap between ‘assumed’ salmon presence and a potential for damming (‘occasional’ to ‘pervasive’) over 387 km. Map 4 illustrates where these overlap are located.  In this catchment these are principally on the lower reaches of the River Druie, Allt-na-Criche, River Nethy and Allt-Mor also the Auchernack burn, Glenbeg bun, Allt Choire Odhair closest to the confluence with the Spey. The mapping of salmon interest is used as an illustration of potential impacts on all migratory fish, with the real impacts likely to be species/site, and time specific. Hence the cumulative effects in the absence of mitigation are hard to predict.

From the appropriate assessment of other salmon SACs (notably the Endrick Water SAC) the HRA conclusions for the River Spey are likely to be similar, i.e. "it cannot be ascertained that there will be no adverse effect on the site integrity of SACs designated for Atlantic salmon and lampreys through dam-building activities and other related activities. Mitigation to avoid these impacts is necessary. It is important to ensure that the passage of fish past any barrier is assured such as by the use of flow devices; this precautionary approach is currently needed due to the existing lack of understanding of the full details of any potential impacts on the SACs. Mitigation to ensure passage may be achieved through the easement or removal of barriers at certain times of year important for salmon (i.e during spawning and smolt emigration) or through the installation of flow control devices. However, it is unclear at this time whether such devices could be used to assist the upstream migration of large Atlantic salmon (which is typical of ‘Spring’ fish). If a beaver dam might cause an adverse effect on the integrity of the SAC and a fish pass might not allow passage upstream, then alternative mitigation measures which will allow passage must be put in place. These mitigation measures should be included in a plan for the individual SACs, which should also set out in what circumstances there could be an adverse effect on site integrity, and a framework through which to implement any mitigation measures should they become necessary."

Hence developing a monitoring and management plan for the catchment would be a necessary means of ensuring there are no adverse effects on Atlantic salmon and sea lamprey. A risk-based approach to monitoring and management will need to be informed by beaver presence. Where beavers are established, it is proposed necessary to carry out surveillance for the presence of dams in key locations at the critical times of year for the spring (smolts) and autumn runs (adults) to locate any beaver dams. Where dams are identified, they should be assessed for passibility and where necessary, agreed dam removal/notching criteria implemented under licence. Going forward it is anticipated that we will acquire greater knowledge of beaver and fish interactions (further research is an action in Scotland’s Beaver Strategy) and the need for ongoing monitoring can subsequently be reviewed.

Removal of dams that are less than two weeks old can take place at any time without a licence from NatureScot. However, the need to ensure fish passage needs to be balance with the wider benefits of beaver dams such that dams are only removed where necessary.

Freshwater pearl mussel

The river Spey supports one of the most significant populations of freshwater pearl mussel in Scotland. Freshwater pearl mussels largely occur downstream from Grantown on Spey with a few colonies in the upper reaches.

There is 140km of river length where adult/juvenile freshwater pearl mussel are assumed to be present in the catchment, of which just 0.4km have predicted potential for ‘occasional’ to ‘pervasive’ damming. Thus the predicted overlap of beaver impacts and freshwater pearl mussel is thought to be low, it is possible that beaver dams trapping sediment upstream of freshwater pearl mussel may be beneficial.

The Conservation advice package for the River Spey SAC notes the pressures on the freshwater pearl mussel include; fine sediment, water quality in the upper catchment, phosphate as a discharge from sewage treatment works, agriculture and distillery discharges, the impact of drought and low water levels in the upper Spey, illegal pearl fishing and the availability of salmonid host species.

Beaver dams in the upper catchment may help to moderate water quality and water supply pressures downstream. However, there is the potential for beaver dams to negatively affect freshwater pearl mussel beds in the smaller tributaries through sedimentation if dams were built over the colony. Again surveillance for dams is recommended where there are known populations and in areas with the potential for recolonisation.

Vascular plants

The national scale analysis of vascular plant records included Botanical Society of Britain and Ireland (BSBI) records from the last 30 years for those species of vascular plants on the Scottish Biodiversity List which are assessed as red or amber in relation to potential risk from beavers. The grid references are at varying scales (10m-100m) and all have been buffered by 50m to allow potential overlap with Potential Core Beaver Woodland. There is no potential overlap with vascular plant species assessed as red in the Spey catchment. There are 33 records of two species assessed as amber within 50m of Potential Core Beaver Woodland. The two species are Calamagrostis purpurea, Scandinavian Small-reed and Carex chordorrhiza, String Sedge. The Great Britain threat status of Calamagrostis purpurea is assessed as “Data Deficient” and Carex chordorrhiza “Least concern” however both are considered ‘Rare’. Both species are located around Loch Insh with 11 records of Carex chordorrhiza and 22 of Calamagrostis purpurea predominantly clustered to the south of the loch.

It is unlikely that Eurasian beaver will target either Calamagrostis purpurea or Carex chordorrhiza directly.  Both are located in habitats which are subject to water inundation during the winter months and are adapted to changing water levels.  Impacts associated with beavers are most likely to be indirect and related to changes in water levels.  Due to its growth habit and nature of the supporting habitat (short sedge communities with winter flooding) it is likely that Carex chordorrhiza is at greater risk of loss than Calamagrostis purpurea should beavers raise water levels across Insh Marshes. 

It is anticipated that both Calamagrostis purpurea and Carex chordorrhiza will adapt to small – scale change in hydrology.  Provided that beavers do not raise the level of water across Insh Marshes all year round, the risk to existing populations of Calamagrostis purpurea and Carex chordorrhiza is assessed as low. Surveillance of both species at Insh Marshes should be implemented to monitor any changes which might be attributable to beaver.

3.2 Hydromorphology and water quality, resource and ecological status.

The catchment has water-courses that fall into all of the classifications of Scottish river types and characteristics from mountain streams, to meandering reaches to modified rivers in agricultural/ rural settings.

The River Spey SSSI Site Management Statement has important context for the features of interest and management pressures on the river. SMS extracts as follows: The River Spey’s hydrology is unique amongst major upland rivers. Whilst the upper and lower catchments are relatively steep and fast flowing, the central section, with a shallow gradient, is more typical of a lowland river, having a broad meandering channel and wide floodplain. The water is low in nutrients (oligotrophic) and, with a relative lack of major industrial developments and intensive agriculture within the catchment; the Spey has remained fairly free from pollution. The River Spey has a variety of freshwater and riparian habitats including beds of shingle, gravel, sand and silt, islands, fringing woodlands and marshes.

Beaver burrowing and damming are the main activities that may influence water resource management. The range of influences have been reviewed by CREW and are considered to be largely positive with beaver presence likely to bring improvements in water quality and, beaver dams to provide benefits in terms of flood attenuation, nutrient and sediment capture.

Beaver’s effect on channel form will likely vary depending on existing physical processes and the location in the system. There is evidence of dams leading to significant deposition of sediment and organic material, effectively grading sediment transport, promoting deposition and reducing local erosion.

Erosion is a natural process in rivers systems and in places is influenced by anthropomorphic modifications. MAP 5 shows the areas with identified geomorphological risk (erosion areas shown, SEPA data (SEPA geomorphological data from Flood Risk map version 1.3)). Overall the extent of areas depicting erosion processes are very limited. Erosion is classed as moderate in all cases and appears to be balanced by deposition. In the Spey catchment the potential bank erosion is concentrated mainly in on the Spey upstream of Kingussie and on the tributaries of the Rivers Feshie and Dulnain. From experiences in Tayside and work carried out by the River Restoration Centre we seen that in some instances beaver activity can result in localised changes to the bank of a river, e.g. when burrows collapse and this can occur in areas already subject to erosional processes.

Burrowing activity on rivers with soft banks has the potential to release sand and silt into the water. As beavers generally prefer slack areas it is anticipated that fine sediment release may be confined to these and will have minimal impact on salmon spawning substrate in the main stem of the river.

The options for mitigating existing excessive erosion and burrowing impacts involve making space for the river to evolve and by having riparian buffer zones or naturalised habitat. Approaches to river-bank protection advocated by SEPA* and NatureScot are based on natural flood management principles and the use of natural materials such as riparian planting and naturalised vegetation to improve resilience or green bank works to stabilise banks. Hard engineering approaches will rarely be appropriate, but may be required to protect specific built infrastructure where a risk is posed by burrowing.

Beaver burrowing has the potential to impact on paths used by a variety of recreational users. The catchment has some significant core paths, many loch and riverside paths and informal access as noted in section 2.1. There are examples of paths, cycle paths and fisheries access that has been locally impacted by beavers in Tayside through tree felling, collapse of burrows and flooding. Such impacts could incur additional costs, however, there are established techniques to address these impacts.

A SEPA catchment profile from 2011 provides much of the background to water resources and existing pressures in the catchment, a number of which are relevant to beavers e.g.   where there are opportunities to enhance water quality, existing barriers to fish passage and control programmes for invasive non-native plant species. The River Spey is classed as one of the cleanest rivers in Scotland and its catchment is described as being ‘almost pristine’. However, there are still areas where water quality falls below expected standards and action is required to improve their condition. Half of the superficial groundwaters (SEPA waterbody classification 2018) classed as ‘Poor’ quality has a beaver dam capacity of ‘occasional to pervasive’. Therefore, there may be potential for beaver dams to contribute to improvements in water quality (Puttock et al. 2017) in these sections (total of 193 km of river length). SEPA carries out routine chemical and biological monitoring of major rivers within the catchment.

Scottish Water provides the majority of drinking water within the catchment via two major groundwater abstractions at Kinakyle (Aviemore) and the Dipple Wellfield (Fochabers). There are also many private supplies for remote domestic properties as well as commercial operations, including many of the catchment’s whisky distilleries. The national spatial analysis highlights there is 1.6 ha of reservoir in the catchment of which overlaps with Potential Core Beaver Woodland (Table 3) at Loch Crunachdan and Allt Phoneis.

The Spey Catchment Initiative was established in 2010 to take forward key actions from the original 2003 Spey Catchment Management Plan (CMP), superseded by the 2016 CMP and the recently published 2023 CMP. This revised CMP brings together the activities of partner organisations and sets out priorities for 2023 to 2030, building on previous successes and incorporating lessons learnt.  Key activities include establishing riparian tree and habitat improvement projects including barrier removal.

3.3 Population and human health

Scheduled Ancient Monuments

Table 5. Scheduled Ancient Monuments that intersect with Potential Core Beaver Woodland in the River Spey catchment.

Spey catchment	Extent of overlap with Potential Core Beaver Woodland (ha)
Cauddwell Castle	0.5
Church of Dundurcas,old parish church	0.002
Deskie Castle	0.089
Knockando House,church	0.0006
Rothes Castle	0.34
Tom Pitlac, Motte	0.23
Total	1.2

Gardens and Designed Landscapes

Table 6. Gardens and Designed Landscapes that intersect with Potential Core Beaver Woodland in the River Spey catchment.

Spey catchment	Extent of overlap with Potential Core Beaver Woodland (ha)
Aultmore	2.7
Castle Grant	60.7
Doune of Rothiemurchus	52.7
Gordon Castle (Bog of Gight)	3.6
Kinrara	23.1
Total	142.8

 

Ancient Trees

There are 543 ancient trees in the catchment of which 182 or 34% overlap with Potential Core Beaver Woodland. MAP 7 shows ancient trees within 10m of Potential Core Beaver Woodland. Based on monitoring of beaver activity/ presence, it is suggested that reactive mitigation through established local volunteer groups could be coordinated as required.

3.5 Material assets

Fisheries

The River Spey is one of Scotland’s premier salmon rivers, with one of the most important salmon fisheries in Scotland. Commercial fishing on the Spey dates back at least 500 years but angling for salmon with rod and line dates back no more than 150 years. Net and coble fishing for salmon was a common feature in the lower reaches and estuary but this ceased in 1993 and angling with rod and line is the only permitted method of capture in use today. Salmon fishing is regulated by the Spey Fishery Board (SFB). A Salmon Conservation Policy  has been in place since 2003. The lower 75km of the river is the most important stretch both in terms of fish caught and income derived from angling. The Spey Foundation are involved with fish survey, monitoring and research. As covered in section 3.1 the release of beaver to the Spey could bring benefits for fish and Salmonids, but there is also the potential for negative effects and hence surveillance for dams and appropriate interventions are advised. Arrangements would need to be put in place to facilitate this surveillance and management and hence there could be additional time and costs considerations for fisheries managers.

Forestry

Map 8 illustrates the National Forest Inventory classes of all woodland in the catchment. A large proportion of the productive woodland is managed by Forestry and Land Scotland.

Foraging impacts are likely to focus on preferred broadleaves species and will likely be constrained to within 20m and occasionally up to 50m of freshwater. Beaver dams can affect drainage over a wider area where the topography is flat.  MAP 9 shows the overlay of areas of steep gradient with Potential Core Beaver Woodland. It could be interpreted that areas with slope in excess of six degrees are less likely to have beaver dams and where dams are built; for their effects to be more localised; whereas there is the potential for drainage to be affected across a wider extent in flat areas next to Potential Core Beaver Woodland. The greater risk of conflict relates to the more productive land uses. The Strath is flat and wide in places and hence there is the potential for localised waterlogging affecting timber crops or forestry access. Where the woodlands are not commercial, these effects are likely to be beneficial by creating areas of wet woodland and standing deadwood. In the future forest plans can seek to accommodate such wet areas as open space or wet woodland, but in the short term there is the potential for some limited impact on commercial forestry.

Beavers have the potential to impact on established and new riparian planting schemes. Whilst it would be possible to use individual tree protection or beaver exclusion fencing for small stands of high value crops, neither approach lends itself to more extensive riparian woodland or planting. Where planting is grant aided, further discussions are required with Scottish Forestry to establish tolerance around beaver impacts, prescriptions for planting in the presence of beavers and the management of other herbivore impacts.

Agriculture

Although a range of farmland has the potential to be affected by beaver impacts, experience from Tayside suggests that impacts are most significant on areas of flat productive land that is reliant on field drainage. The overlap between Potential Core Beaver Woodland and Land Capability for Agriculture (LCA) classes in the River Spey catchment is illustrated in Map 10. The River Spey catchment has a total of 1193 ha of Prime Agricultural Land (PAL - defined as LCA classes 1 - 3.1) capable of arable production, of which there is 41 ha that overlaps with Potential Core Beaver Woodland. This equates to 3.4% of the total area of PAL land. There is 366 ha of LCA class 3.2 (mixed agriculture) that overlaps with Potential Core Beaver Woodland (3.2% of the total extent of LCA 3.2). The more productive LCA classes (1 - 3.2) are all downstream of Aberlour as shown in Figure 5. For comparison, there is 587 ha of LCA 1-3.1 and 861 ha of LCA 3.2 that overlaps with Potential Core Beaver Woodland in Tayside.

As an overview it is likely that beaver activity will have a varying impact on some individual farms in the catchment. Where beaver impacts can be tolerated there will likely be a range of environmental benefits. Mitigations such as leaving margins and buffers for beavers will help to reduce conflicts. Some farms with diversified interests may also benefit from visitor/ guest accommodation where beaver presence may be attractive to visitors.  From experience in Tayside negative impacts are most likely to be from the damming of burns and drainage ditches and to a lesser extent from burrowing impacts into river banks and embankments.

The economic significance to individual farms will vary depending on the type of farming, the extent of land that is available to them to farm and the extent to which they are able to switch areas of production away from areas that may be affected by beaver activity. The Beaver Management Framework provides an existing framework for addressing such negative impacts, although will inevitably incur some additional time costs and inconvenience for those affected. In some cases licenced intervention may be merited. This includes dam modification, flow devices or beaver removal. However, we expect the need for licensed intervention to be relatively small-scale and at least initially to focus on interventions towards the lower end of the beaver management hierarchy, i.e. dam modification or removal rather than beaver removal. To note, crofting is more prominent in the upper catchment, and can still meet the licensing purpose under “the prevention of serious damage to agriculture” with the assessment of damage taking account of the effect on the ability to croft.

The presence of embankments and the risk of beaver burrows contributing to bank failure poses a specific risk and there have been examples of breaches in Tayside in spate conditions where there are existing river erosion pressures. The national spatial analysis indicates there is around 71 km of recorded embankment (SEPA data) in the catchment, of which 15 km (21%) overlaps with Potential Core Beaver Woodland, refer to MAP 11. This extent of overlap is the same as in Tayside where embankments principally protect areas of Prime Agricultural Land used for arable and vegetable production.  However, in the upper Spey catchment the embankments are generally protecting land used for livestock grazing and in places such as Insh marshes, removal of embankments are being proposed to promote Natural Flood Management and habitat restoration.  

The options for mitigating impacts in such cases are again focused on making space for the river and potentially moving embankments back from the river, ideally more than 20m, where most beaver activity is focused. There are existing existing agricultural support measures that support the restoration and protection of riverbanks, but such works can be costly. Protected Species Licences may be appropriate where there is a risk of burrowing impacting on adjacent land use. There is currently work ongoing to develop tools that will enable better assessment of the risks posed by burrowing impacts.

Distilleries

More than half of all Scotland’s malt whisky is produced on Speyside and the industry makes a significant contribution to the local economy, particularly in Moray. It is anticipated that potential issues arising from beaver activity would be suitably managed through either mitigation or licensing approaches as set out under the Beaver Management Framework.

3.6 Infrastructure

The catchment has 20km of trunk roads that overlap with Potential Core Beaver Woodland, 46 km of A and B roads and 213 km of minor road. Of the 106 km of railway within the catchment, there is 11 km of overlap with Potential Core Beaver Woodland (with a 10m buffer).

The rail line runs from Inverness to Perth directly adjacent to the Insh Marshes complex where there is proximity to PCBW as shown in MAP 11. Another additional stretch of railway that overlaps with potential beaver habitat is between Carrbridge and Slochd (where the habitat may be less favourable).

The 2022 SEA Addendum recognised the potential for negative effects on infrastructure on floodplains. Going forward, where possible, conflicts can be managed through proactive planning that seeks to make space for water and pre-empt where conflicts may arise. Issues that arise with existing structures may require mitigation and management.  Again, the Beaver Management Framework provides the means to address these impacts through species licensing or mitigation. In the case of serious impacts on railway lines there will be imperative public safety considerations.

Network Rail have been proactive in monitoring and mitigating beaver burrowing impacts at other locations in the rail network in Tayside. The section of railway crossing Insh marshes poses a particular challenge as there is potential for beaver impacts along this length and it is difficult to predict precisely where beavers may choose to lodge or burrow. The line is already ‘floated’ and designed to deal with natural fluctuations in water levels. Further changes in water levels are unlikely to occur at scale in the Strath attributable to beavers; hence, the main impacts of concerns are likely to be burrowing into the embankment as a ‘dry site’ to lodge next to the adjacent wetland. There may be opportunities as part of electrification works to ‘beaver proof’ sections of the railway line following the hard engineering approaches that have been used to protect flood defences in other parts of Europe. However, such mitigations will be costly for such a significant length of overlap. Detailed analysis of the route and hydrology may help to risk assess where such mitigations would be most likely to be needed. The alternative is a reactive approach which would require regular inspections in areas where beavers are established. Whilst Insh marshes presents one of the largest extents of beaver suitable habitat nationally, we can foresee there could be significant potential for conflicts from the juxtaposition of the railway line.

4.  Summary of key report findings

Table 7. Summary of likelihood and significance of beaver effects within the River Spey catchment.

SEA category	Receptor or interest potentially affected	Effect	Likelihood of impacts	Significance in absence of mitigation	Specific mitigation/ actions proposed should a licence for release be issued
Biodiversity	Other interests comprehensively reviewed in Beavers in Scotland Report and 2017 SEA – not repeated here for brevity	+	High	NA	Largely positive
Biodiversity	Riparian woodland	+/-	High	High	Risk assessment and monitoring of designated woodlands. Management of herbivore impacts at a level that can support beaver presence. Exploration of using beavers as a means of further promoting the restoration of riparian woodlands.
Biodiversity	Aspen	+/-	High	High	Risk assessment and implementation of monitoring and proactive protection of specific trees/stands where appropriate. Wider management of the aspen resource to promote resilience.
Biodiversity	Bryophytes and lichens	+/-	Low	High	Risk assessment and implementation of monitoring and proactive protection of specific trees where appropriate. Some additional survey may be required where there is insufficient information on lichen distribution.
Biodiversity	Highlighted vascular plants	Neutral/-	Low	Medium	Surveillance of known populations of species of conservation interest.
Biodiversity	Salmon	+/-	Medium	High	Risk assessment and implementation of dam surveillance programme and development of a management plan to ensure timely intervention to ensure unimpeded fish passage. Aligned with monitoring there is a need for research to determine the pass-ability of beaver dams by adult salmon (upstream) and smolts (downstream), into the wider effects (positive and negative) of beaver on salmonid/fish populations, and into the effectiveness of flow devices incorporating fish passage.
	Freshwater Pearl Mussel	+/-	Low	Low	Surveillance for dams in the smaller tributaries where FWPM are present or may re-establish.
Water quality, resource and ecological status.		+	High	NA	Benefits will be tempered where dam removal is required.
Population and human health		Neutral	Low	High	Disease screening protocol and additional public health surveillance.
Cultural heritage		Neutral/-	Low	High	Site specific mitigation as required
Material assets	Forestry	+/-	Medium	Medium	Existing measures through the Beaver Management Framework to mitigate or consider the use of licensing approaches. Exploration of impacts on forestry grants and herbivore management requirements and opportunities for beavers to promote riparian woodland restoration, consideration of future design plans to accommodate component of wet woodlands.
Material assets	Fisheries	+/-	Medium	High	As for salmon.
Material assets	Agriculture	+/-	Medium	Medium	Existing measures through the Beaver Management Framework to mitigate or consider the use of licensing approaches. Opportunity to work with farming interests to deliver environmental benefits that are supported by rural support mechanisms.
Infrastructure	Railways	Neutral/-	High	High	Existing measures through the Beaver Management Framework to mitigate or consider the use of licensing approaches. Opportunity for pro-active mitigations as part of line works.
Infrastructure	Roads	Neutral/-	Medium	Medium	Existing measures through the Beaver Management Framework to mitigate or consider the use of licensing approaches.

 

ANNEX

Find out more 

• River Spey Habitats Regulations Assessment of the potential effects on Natura sites in the catchment.

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