Beavers in Scotland: consultation on the strategic environmental assessment

4.14 Beavers and Material Assets

4.14.1 Beavers and Forestry

4.14.1.1 How beaver activity affects forestry

As detailed in section 4.2, the main mechanisms by which beavers affect woodland are tree-felling (for food and construction) and flooding. They use most Scottish broadleaved species but generally avoid conifers, although they may occasionally ring-bark them or feed on saplings in the late winter/early spring. They may also fell them for construction purposes if few broadleaved trees are available. Since most Scottish forestry relies on conifers, beavers are unlikely to have much impact through felling. None of the major coniferous species is tolerant of prolonged flooding, so beaver impoundments would lead to the death of trees within the flooded area. Flooding will also affect forestry infrastructure (e.g. forest tracks, culverts) and access for forest management, deer management and recreation, where it overlaps with inundated areas.

Relatively little information is available on the impact of beavers on forestry. Damage to forestry by felling is reported only where broadleaved tree species are managed commercially, but minor damage from flooding is more widespread. This is largely anecdotal, although a Polish survey reported that 3,200 ha out of a total of 27,472,000 ha (i.e. 0.01%) of agricultural and forestry land in Poland was flooded by beavers. In addition, 65 km of embankment and 229 culverts were affected, but it is not known whether these were in forested areas. Given that, at the time, Poland had a population of 18,000-23,000 beavers, this suggests a relatively minor impact on forestry. However, there is less rainfall in Poland and there is likely to be less use of culverts there than in Scotland, so any comparisons should be treated with caution. It has also been reported that 0.1% of the productive forest in a 34.7-km ² study area in south-eastern Norway was flooded as a result of beaver dams. Finnish foresters have expressed more concerns about beaver damage than Norwegians, probably because of smaller mean property size, making the cost of even small areas of damage relatively high for the individual foresters affected.

The Scottish Forestry Strategy is the Scottish Government's framework for taking forestry forward through the first half of this century and beyond. It identifies timber production as a core theme, but also sets out six others: climate change, business development, community development, access and health, environmental quality and biodiversity. Therefore, although beaver presence will result in some costs to forestry, it will also bring about a range of benefits that will contribute to the outcomes set out in the strategy, such as improving the health and wellbeing of people, and ensuring a high-quality, robust and adaptable environment. This approach is further developed in the strategy for Scotland's National Forest Estate, which highlights the multi-purpose role of the estate and the growing emphasis on integrated land management, including its substantial contribution to the Scottish Biodiversity Strategy.

Maps 24 and 25 below detail the extent of the beaver policy areas and the National Forest Inventory ( NFI) cover (these are reproduced as A3 maps in Appendix 1 for ease of reference). Within this area beaver activity and impacts will be restricted to some freshwater features and the immediate riparian habitat.

Map 24 - Knapdale Beaver Area and National Forest Inventory cover

Map 25 - Tayside Beaver Area and National Forest Inventory cover

Table 4.14.1 Summary of positive and negative effects of beaver on forestry activities

Activity	Mechanism	Positive effects	Negative effects	Notes
Felling	Change in riparian woodland	Enhancement of biodiversity elements of commercial forestry plantations Presence of beavers could be used in support of the funding of planting schemes in riparian areas	Whilst beavers use most Scottish broadleaved species but generally avoid conifers, they may occasionally ring-bark or feed on conifer saplings in late winter or early spring or if few broadleaved trees are available. Given the extent of overlap of core beaver woodland habitat and commercial forestry however, the effect is likely to be minimal. The presence of beavers could discourage the planting of commercial broadleaves in some areas.
Felling	Change in riparian woodland: Change in age classes of trees		Implications for deer management planning
Felling	Change in riparian woodland: Change in relative abundance of different tree species		Possible reduction in deep-rooted species that bind bank material, and therefore possible increase in erosion Minor, localised reduction in timber availability in longer term	Timber availability likely to be a minor impact, as Scottish forestry relies mainly on conifer species which are unattractive to beavers
Felling	Change in riparian woodland: Amount/ diversity of fallen dead wood on woodland floor	An increase in standing dead wood, which is generally present at only low levels in British woods
Dams/pond creation	Change in hydrological processes on riparian and downstream habitat	Hydrological cycle and water flow maintenance - increased flood storage, and therefore a decrease in downstream flooding	Increased flooding of riparian zone and beyond, so potential impacts on land use such as timber (indirect impacts due to localised flooding), plus infrastructure (direct impacts due to localised flooding of roads and tracks, blocking of culverts, etc.)	Problems resulting from leaching of nutrients from soils are more likely in catchment areas that are fertilised
Dams/pond creation	Change in hydrological processes on riparian and downstream habitat	The development of a robust and adaptable environment	The loss of commercial forestry conifers and certain broadleaves within the flooded area Impacts on forestry infrastructure such as culverts tracks and access for forestry management such as deer management etc. where these are within the flooded area
Dams/pond creation	Change in standing deadwood resulting from inundation of trees	Death of trees which are unable to cope with the water levels will lead to an increase in standing dead wood, which is generally present at only low levels in British woods
Indirect habitat creation/restoration initiatives as a result of beaver presence	Beavers used to promote opportunities for riparian and freshwater habitat creation/restoration	Any riparian woodland restoration programme will aim to increase the abundance of this much reduced habitat, and of particular preferred species, such as aspen		Further research on the localised flooding of forestry areas would also help clarify potential impacts of beavers.
Other	Beavers used to promote health benefits	Further attraction of visitors to forest/woodland environments - improving the health and wellbeing of people, and ensuring a high-quality, robust and adaptable environment (an outcome set out in the Scottish Forestry Strategy).

4.14.1.2 Assessment of effects on forestry interests within the Beaver Policy Areas

Beavers are currently present mainly within the Taynish and Knapdale Woods SAC component of Knapdale, which is managed primarily for conservation, so any impacts on commercial tree species in these areas might be considered acceptable unless they have a negative ecological impact. In the short to medium term, beavers would be expected to colonise other parts of Knapdale and move more widely outside the SAC. The terrain would limit areas vulnerable to inundation due to beaver activity. However, depending on the site of future dams, including the blocking of any culverts, it is possible that forest tracks might be flooded, affecting forestry activities. The level of deer management may also need to be reviewed to take into account the ability of trees felled by beavers to re-sprout and the longer term implications for woodland structure and quality.

The potential for beavers to affect forestry in Tayside is greater, as broadleaved tree species are managed commercially in parts of this area and, because of the flatter terrain, a greater proportion of the land is accessible to beavers. Based on experience elsewhere in Europe, it seems unlikely that impacts will be severe at the catchment scale, although they may be more significant at the very local scale.

4.14.1.3 Mitigation measures and opportunities

The UK Forestry Standard Guidelines on Forests and Water provide statements of requirements for sustainable forest management. The guidelines specifically highlight the environmental roles of the riparian zone and the need to identify effective buffer areas to protect them and aquatic habitats. Forest managers are required to identify and set aside such areas to help buffer any potentially adverse effects of adjacent forest management. The recommended minimum buffer widths range from 10 m wide along watercourses less than 2 m wide, 20 m along lochs, wetlands and watercourses more than 2 m wide, and 50 m wide along abstraction points for public or private water supply. Therefore, riparian zones should already be set aside by forest managers where most beaver activity is likely to be concentrated. However, in some cases the location of riparian zones will change as a result of beaver activity, which will mean changes to the location of buffer areas. Beavers will add a new dimension to how the guidelines are applied.

The diversification of the national forest resource is currently under way and it is likely that larger areas of more productive broadleaved tree species will be planted, including more substantial floodplain forests, where beavers are likely to have a particular impact. The development of strategic planning, and appropriate best practice management, will be required to deal with negative beaver impacts and issues, including mitigation against flooding and the management of forest operations near breeding lodges. There are also opportunities for forestry in terms of the biodiversity and socio-economic benefits that beavers can bring, and should also be included within any management planning.

Section 5 also details the hierarchy of mitigation techniques that can be used to address impacts from beaver activities, including generic management and licencing approaches to more practical measures including those addressing:

• Dam building activities
• Burrowing activities and
• Foraging activities

These mitigation measures apply to the potential negative effects identified in relation to beaver activity and forestry operations.

4.14.2 Beavers and Fisheries

4.14.2.1 How beaver activity affects fisheries interests

The potential for interactions between beavers and fish have been reviewed extensively, and details of these have been summarised within the Beavers in Scotland ( BiS) Report. Whilst these reviews focused on the potential impact of beavers on 'fish' rather than 'fisheries', it is clear that any impacts on fish of commercial or sporting value may also have direct impacts on associated fisheries. Published data on the direct impact of beavers on freshwater fisheries outside Scotland are surprisingly few.

From a fisheries perspective, it is likely that the two species which are most likely to be influenced by the presence of beavers are Atlantic salmon and trout. Whilst Atlantic salmon and trout co-exist across much of their range, they differ in respect of their in-stream habitat requirements. As well as differing in their usage of in-stream habitats, trout do not make as much use of larger tributaries for spawning as Atlantic salmon. This means that beaver activity on small streams may have a disproportionate importance for trout production. The contribution of trout from these streams to the overall fishery resource within the Scottish river catchments, including the supply of fish to already declining sea trout fisheries, is a key consideration.

When assessing the scale and direction of any possible interactions between beavers and fisheries (for any species), it is important that the ecological requirements and behaviour of beavers, and the fish species concerned, are understood. The ecology of Atlantic salmon is well understood and the ecology of Eurasian beaver can be broadly inferred from published literature, including that arising from the Scottish Beaver Trial ( SBT). This approach allowed the Beaver Salmonid Working Group ( BSWG) to assess the potential magnitude of spatial overlap between the possible range of beavers and the distribution of salmon. These analyses suggested that a large overlap would generally be expected but will vary spatially, both within and between catchments.

This does not infer that the level of overlap equates to the total area over which interactions between beavers and Atlantic salmon may occur. Neither does it predict the scale or direction of any impact. The BSWG report suggests that whilst tributaries can be important spawning and rearing areas for Atlantic salmon throughout catchments, the upper tributaries which are commonly used to produce the spring Atlantic salmon stock component are currently under the most threat, and hence are the most vulnerable to any obstructions from beaver dams.

In some areas, beaver activities and dam-building may have positive effects on factors such as water quality downstream. Conversely, obstructions at the downstream end of important tributaries, such as those used by the spring stock component of Atlantic salmon populations, may affect access to important spawning areas.

The impact of beaver activity on other native species for which recreational fisheries exist in Scotland, such as pike, roach and perch, may be less controversial. These are species which utilise a wide range of habitats and can establish in both rivers and standing waters. Whilst these species do undertake spawning migrations, or spawning movements, they are possibly less likely to be found in situations where they are affected by beaver dams.

In streams where beaver and salmonid habitats may overlap, interactions will vary over time, between catchments and within catchments. As such, it is not possible to predict with certainty whether the overall net impact of beaver presence will be positive, negative or negligible on salmonid fish or other species of conservation importance. However, beaver dam-building activity, and the associated potential hindrance to fish passage, is of particular conservation concern to a component of the Atlantic salmon stock called spring salmon, which utilise upland nutrient-poor streams.

It is widely accepted that the Eurasian beaver is a natural component of Scotland's wildlife heritage and that it was lost as a result of man's activities. Atlantic salmon and other native freshwater species, such as trout, European eel and lamprey, evolved with beavers over millennia and clearly these species co-occurred in Scotland.

Past and recent reviews, as well as the report of the BSWG, acknowledge that beavers can have overall positive effects on the production of some species of fish. This is largely because of the ability of beavers to modify river habitats and, as a consequence, influence hydrological characteristics and water chemistry within the watercourse. This must, however, be balanced against possible negative impacts of dam-building on the movement of fish within river systems and their effect on critical in-stream habitats.

The likely positive and negative effects identified in section 4.11 relating to Beavers and Fish (which include those of fishery significance) have been reproduced here for ease of reference.

Table 4.14.2 - Summary of positive and negative effects of beaver on fisheries interests.

Activity	Mechanism	Positive effects	Negative effects	Notes
Felling	Change in riparian woodland: Opening of woodland canopy and increased patchiness	Increased light penetration may lead to increased production within streams, ponds and lochs. Increased primary productivity and temperature may increase production of aquatic macroinvertebrate prey items for fish. This could lead to increased fish productivity and improved individual growth rates. Increased temperatures may favour the establishment of non-salmonid species which have a higher tolerance to lower dissolved oxygen concentrations (such as cyprinids and sticklebacks). Increased light may lead to the establishment of macrophyte communities, creating complex habitats that offer shelter to some fish species (such as pike, perch, roach and sticklebacks) and their prey. Penetration of light to the riparian zone may result in the development of plant communities that will stabilise banks, reduce erosion and provide increased opportunities for greater terrestrial input of food items for fish.	Reduction in shading has the potential to increase water temperature and result in increased thermal stress upon some fish species, particularly salmonids. Increased temperatures may favour the establishment of fish species which may compete with, or predate, salmonids. Increased temperatures can contribute to reduced levels of dissolved oxygen in some circumstances. This may unfavourable for some fish species (such as salmonids)	Tree felling may also undo some of the extensive tree-planting restoration work that has taken place in some catchments (particularly the upper areas of catchments which have little natural tree cover)
Felling	Change in riparian woodland: Change in relative abundance of different tree species	Possible changes in the amount of allochthonous material derived from different sources (principally leaf litter) which may benefit some aquatic macroinvertebrates, and potentially the fish which prey on them.	Possible reduction in type and quantity of allochthonous material (principally leaf litter) may lead to a reduction in aquatic macroinvertebrate community composition and production. This may negatively affects fish which prey on them. Possible reduction in the quantity of terrestrial (invertebrate) prey items that enter the aquatic environment as food for fish.
Felling	Change in riparian woodland: Change in age classes of trees	Possible changes to tree age class in riparian or littoral areas may result in a more open canopy and increased light penetration, with consequent benefits for some species (see above)	Loss of mature woodland may result in lesser quantities of allochthonous material entering waterbodies. This can affect macroinvertebrate production and therefore the production of fish. Possible reduction in size and quantity of large woody debris entering the watercourse in longer term may impact in-stream habitat structure, and this may adversely affect some fish species. Possible changes to tree age class in riparian or littoral areas may result in a more open canopy and increased light penetration, with consequent negative effects for some species (see above)	Effects will depend on nature of changes, and the extent to which trees affected by beavers regrow. See Table 3.4.1 for beaver effects on woodland trees.
Felling	Change in riparian woodland: Amount/ diversity of fallen dead wood on woodland floor
Felling and constructions	Changes in amount/diversity of woody material in watercourses	Greater quantities of large wood items in streams, rivers and lochs can result in increased in habitat diversity, and an increase in the availability of prey items and fish cover. Where large woody debris occurs, it may reduce the transport of sediment downstream.	The establishment of large log jams could hinder the in-stream movement of some fish species if they act as barriers. Depending on where woody items aggregate, such material can act as a barrier to movement, or result in the loss of habitat. Where the quantity of large and small woody items is too great, this may result in blockages which may impact the transport of important gravels.
Feeding	Feeding on specific terrestrial herbaceous and aquatic plant species	Changes to macrophyte community structure may favour some species of (non-salmonid) fish and their prey.	Decrease of macrophyte species in some lochs may have a negative impact on species that depend on them for food or shelter. Pike, for example, are often associated with macrophytes because they use these as cover when ambushing prey. Roach and perch may utilise macrophytes as cover from pike. Salmonids are rarely associated with macrophytes.
Dams/pond creation	Change from lotic to lentic habitat	Increase in habitat diversity which may favour some fish species or fish life history (ontogenetic) stages. In some situations this may also result in an increase in species richness - of both fish and invertebrate prey items. Increased temperatures, changes in habitat availability and feeding opportunities in lentic habitats may result in increased individual growth rates, fish condition and overall production. Depending on depth and location, impoundments may offer a high temperature refuge for some fish.	Increase in habitat diversity for fish may favour some species over others, or benefit only some life history stages (e.g. juvenile or adult fish). Depending on location, the creation of lentic habitats may result in habitat loss for species which favour or dominate lotic habitats. Accumulation and smothering of bed sediment upstream of dams, and a reduction in habitat quality for some species (principally salmonids) Reduction in turbulence (or mechanical mixing) may occur upstream of dam resulting in a reduction in dissolved oxygen. Possibility of increased opportunities for fish predators (e.g. piscivorous birds, mammals such as otter, or man).
Dams/pond creation	Change in hydrological processes on riparian and downstream habitat	Reduction in the transport of fine material may improve the quality of spawning and rearing habitats downstream of any impoundment. Impoundments may create low and high flow refuges for fish. Flooding of riparian and wetland habitats can provide spawning opportunities for species such as pike, and additional habitat for species such as European eel.	Changes in flow may result in sediment starvation in gravel spawning areas. This can affect both salmonids and spawning lamprey. A reduction in flow downstream of the structure may result in a reduced wetted width and a loss juvenile fish habitat.
Dams/pond creation	Changes in water quality downstream	Reduction in the amount of fine material deposited on stream or river bed downstream of the impoundment. This may result in an improvement in the quality of gravel spawning areas (downstream) for salmonids and lamprey. Accumulation of fine sediments may increase the volume of available habitat for lamprey ammocoetes.
Dams/pond creation	Change in standing dead wood resulting from inundation of trees
Dams/pond creation	Longer term successional changes after dam abandonment e.g. beaver meadows
Dams/pond creation	Impacts on movement of species		Prevention of the free movement of fish to all habitats required during their life cycle. This is particularly relevant to key migration periods (such as spawning migrations), but also at other times. The scale of impact may be greater for species which have a limited ability to overcome in-stream obstacles (such as lamprey).
Other constructions	Creation of lodges, burrows, canals etc.
Other	Fisheries		Beaver habitats (impoundments and flooded wetlands may benefit North American signal crayfish, an invasive non-native species, if these are present within the catchment.
Indirect habitat creation/restoration initiatives as result of beaver presence	Beaver used to promote opportunities for riparian and freshwater habitat creation/restoration	Presence of beaver may act as an incentive for greater investment, management and monitoring. Including those related to the restoration and management of riparian woodland.	Beaver presence may eliminate fish-related riparian woodland restoration activities that are currently underway.

4.14.2.2 Distribution of fisheries interest in Beaver Policy Areas

Knapdale

The fisheries resource in Knapdale is largely limited to brown trout because anadromous salmonids (Atlantic salmon and sea trout) are not able to migrate freely into the Knapdale Forest area. Whilst brown trout undoubtedly utlise stream habitats within the area covered by the Knapdale beaver trial area, only those fish which inhabit the standing waters (lochs) are used as an angling resource. These fish, whilst resident in lochs for the majority of the year, may still use local streams at spawning time, and these remain an important area for maintaining brown trout populations within the areas occupied by European beaver.

Tayside

The River Tay supports significant recreational fisheries for Atlantic salmon, trout (including sea trout) and grayling. It is one of the most iconic of the Scottish Atlantic salmon rivers and the number of rod-caught Atlantic salmon makes it one of the most important catchments for this species in the UK. Data available for 2016 showed that the Tay rod catch (6,590 fish) was the third highest in Scotland in that year.

The spring salmon rod catch in 2016 was 582 fish and was the highest spring catch recorded in Scotland. All of these fish are now returned to the water after capture in line with the requirements of The Conservation of Salmon (Scotland) Regulations 2014. The River Tay remains important for this stock component in a national context.

The Conservation of Salmon (Scotland) Regulations 2016, determine whether the exploitation of Atlantic salmon is sustainable, through a process of measuring catch against the estimated number of fish required for the population to reach its conservation limit. In 2016, the River Tay SAC was considered to be a 'Grade 1' river, which means that there is at least an 80% chance of the Atlantic salmon population reaching its conservation limit and that exploitation levels are currently sustainable.

A recent database was produced by SNH to identify river sections which are less likely to be dammed based on two main criteria: river widths greater than 6 m and the absence of potential core beaver woodland. This showed that, for the River Tay, which has a total river length of 1,029 km, a low likelihood of dam-building was estimated, along about 93% of the river.

Maps 26 and 27 below detail the extent of Atlantic salmon rivers in relation to core beaver woodland (these are reproduced as larger maps in Appendix 1 for ease of reference).

Map 26 - Knapdale salmon rivers and potential core beaver woodland

Map 27 - Tayside salmon rivers and potential core beaver woodland

4.14.2.3 Assessment of effects on fisheries interests within the Beaver Policy Areas

Knapdale

Opportunities to monitor the impact of the beaver reintroduction at Knapdale have been limited. Recreational angling within the SBT area is controlled by the Lochgilphead & District Angling Club ( LADAC). LADAC maintains boats for its members and carries out light stocking activities to supplement brown trout populations within each of the 15 hill lochs that it manages. There was no indication during the trial period that beavers, which utilised the lochs more extensively than anticipated, negatively affected the operation of Loch Barnluasgan and Loch Coillie-Bharr as a recreational fishery.

The potential for using Knapdale as a study site for assessing the impact of beavers on stream fisheries is extremely limited because these areas are themselves not used as a fisheries resource. These streams do, however, provide spawning habitat for those fish which are present in connected standing waters. The existing monitoring programme has already provided some evidence that trout are able to utilise spawning habitat in the presence of beavers, although these data are limited.

All angling in the Knapdale area is restricted to standing waters. These waters are regularly, but lightly, stocked by LADAC with brown trout. Rainbow trout have also been stocked into at least one loch within the area. Baseline data for fish in standing waters within the Knapdale area are lacking, making an assessment of fisheries impact difficult.

Tayside

Although little is known about the actual impact of beaver activity on fish in Scotland, the potential for fishery impacts within the River Tay is considered high, particularly if beaver management measures are not in place.

The River Tay SAC is currently in favourable condition for its Atlantic salmon, lamprey and otter conservation features, and deterioration from this status, for any feature, should be prevented. This suggests that a careful assessment of the potential and current impact of beaver not only on Atlantic salmon, but also on brook lamprey, river lamprey, sea lamprey and otter should be carried out to ensure that deterioration in conservation status is avoided. For Atlantic salmon, the Scottish Government must also consider its international obligations, such as those to the North Atlantic Salmon Conservation Organization ( NASCO), to maintain and manage this species. See section 4.11 for further detailed assessment of beavers in relation to fish, including those of fishery significance.

Angling within the River Tay catchment is not, however, restricted solely to Atlantic salmon, and well-developed riverine fisheries exist for a range of other species, such as trout and grayling. These are well described within the Tay District Fisheries Management Plan. Trout are, as in most Scottish fresh waters, the most widely distributed fish within the Tay catchment, including upland areas that are inaccessible to Atlantic salmon. Both brown trout (the freshwater resident form of S. trutta) and sea trout (the anadromous form) typically spawn in small watercourses that range from 1 to 3 m in width, and these fish may migrate over short and (particularly in the case of sea trout) long distances to reach these areas. Both forms of trout are exploited by anglers, although information relating to the actual contribution of this species to the local economy is lacking. As a function of their widespread distribution within small watercourses, it is possible that the potential overlap between beaver activity and trout may be more significant than has been estimated for Atlantic salmon. It is therefore not possible at this time to predict what impact reintroduced beaver might have on trout fisheries within the River Tay catchment.

Grayling are not native to Scotland, but have been present in the River Tay since the nineteenth century and have spread throughout the main stem of the Tay, the Isla, the lower Tummel and the Earn. Grayling angling, mostly on a catch-and-release basis, is well established in these watercourses. As this species appears to be limited to relatively large watercourses, the interaction between beavers and grayling may be less than that predicted for Atlantic salmon and trout. Little information is available relating to the population status and local ecology of grayling within the River Tay system, and few data are publicly available on the numbers of grayling caught and its value to the local economy. This makes an assessment of the impact of beavers on the grayling fishery difficult.

Both the European eel and pike are present within running waters in the Tay system. European eel is widely distributed throughout the catchment, although pike is limited to slower-moving reaches of the larger river systems and standing waters. Although angling for pike is popular where they occur within the system, this activity appears to be unregulated and unmonitored. Both European eel and pike are species which benefit from the presence of impoundments and the creation of wetland habitats. For instance, a study of fish community structure in the Canadian Shield Lakes suggested that North American beavers had an overall positive impact on pike abundance and productivity. It might be expected that a similar response could occur in relation to the Eurasian beaver. Perch and roach are probably not native to the Tay catchment and are also present in slower-moving reaches of the larger river systems, as well as some standing waters. Similar to the situation for pike, this fishery is unregulated and unmonitored. The ecology of these species suggests that they may also benefit from the presence of beaver-created impoundments and the creation of wetland habitats.

4.14.2.4 Mitigation Measures

The development of a management strategy is key to the successful coexistence of beavers and fisheries. The BSWG is clear that such a strategy should be a fundamental prerequisite of any decision to license the reintroduction of beavers in Scotland. This strategy should provide guidance on type(s) of interventions which can be made, the evidence base required and resourcing. The strategy should be developed in full consultation with stakeholders from the fisheries management sector.

The group recommended that this management strategy should be developed in full consultation with all key stakeholders. From a fisheries perspective, this would also include representation from trout and grayling anglers as well as input from the coarse angling sector. The BSWG report also recommended that any strategy should consider the following:

• The construction of beaver dams, beavers at pinch-points adjacent to in-stream human infrastructure including culverts, weirs and fish passes. Experience from abroad and recently in Scotland suggests that in this particular scenario, fish passage concerns may be exacerbated, presenting an elevated requirement for management intervention. A GIS-based analysis of the overlap of areas predicted to be less likely to be dammed with existing anthropogenic watercourse structures showed that 78% of all culverts, weirs, and fish passes in Scotland were at locations where damming was less likely. However, of key importance is the location of impassable dams, and the reduction in accessible habitat that they would cause. Further analysis could be done in the future to highlight which structures risk impeding Atlantic salmon access to key habitats.
• The development of a beaver management strategy, which should set out minimal intervention approaches as well as the criteria by which relocation or lethal control of beavers would be appropriate for the conservation of salmonids. The BSWG recommendations go on to state that beaver presence alone should not be a trigger for action and that a strategy should allow a range of management interventions to be undertaken from short-term action to longer-term intervention. The requirement or otherwise for such intervention may be determined partly by river flow levels, and may be necessary in advance of fish migration periods during spring and/or autumn, particularly during prolonged periods of low flow
• The imperative of ensuring free passage of migratory fish suggests that any management strategy should recognise the dynamic nature of beaver dams and the resources required in assessing such structures on multiple occasions. In addition, any removals of dams from watercourses must adhere to current regulatory guidance and be completed without causing pollution or affecting stream biota
• The resource implications associated with monitoring and management. The BSWG considered it vital that such resources are committed, over the medium to long term, to relevant management authorities
• The significant gaps in our knowledge of beaver-salmonid interactions, both within Scotland and abroad. Further research in Scotland is considered necessary to help inform when management intervention may, or may not, be required
• The potential, and possibly extensive, overlap between known Atlantic salmon distribution and potential beaver habitat in major rivers, with potential overlap in minor rivers varying considerably between catchments. Both the mapping study carried out by MSS and the more recent GIS-based analyses of dam-building potential in SACs suggest significant variability in the extent of areas likely to be affected

Section 5 also details the hierarchy of mitigation techniques that can be used to address impacts from beaver activities, including generic management and licencing approaches to more practical measures including those addressing:

• Dam building activities
• Burrowing activities and
• Foraging activities

These mitigation measures apply to the potential negative effects identified in relation to beaver activity and fisheries operations.

4.14.3 Beavers and Infrastructure

4.14.3.1 How beaver activity affects Infrastructure

Infrastructure and general land use will tend to be at risk only where they are in proximity to beaver activity, and therefore near running and standing waters. Impacts can arise from the direct and indirect implications of dam-building, burrowing and tree-felling. Since beavers readily use natural, semi-natural and artificial waterbodies, the likelihood of beavers coming into contact with human infrastructure is high. The scale and significance of the resulting impacts will vary according to local circumstances, but in most situations management will be required, with associated costs.

There is limited information in the literature about beaver impacts on such issues, so many of the following experiences have been collated from discussions with European and North American colleagues, from a recent review of beaver management and from Scottish experience to date.

Felled trees have the potential to cause incidental damage when they fall on fences, power lines, buildings or transport routes. Although the frequency of these events is rare, if they occur they may be significant in terms of disruption, cost and risk to human wellbeing.

Roads and tracks

Dam-building on a stream, ditch or pond outflow can cause direct flooding of an adjacent road or access track. If this is located in a low-lying area, the scale and depth of flooding can cause significant obstruction until the dam is removed or managed. Beaver burrows may also undermine roads, tracks and other structures, causing subsidence.

Culverts, weirs, sluices, fish passes

Although beavers normally construct dams using natural foundations, they can also use man-made structures. Even with no beavers present, such structures tend to be vulnerable to blockage by water-borne debris, and therefore need regular checking and maintenance. Beaver activity, however, can exacerbate problems. There are many records from across Europe and North America of beavers building dams across the mouths of culverts, on sluices and weirs and on fish counters and fish passes. Any suitable structure located in water can be used in this way.

Subsidence caused by beaver burrows can also lead to in-stream structures, such as weirs and fish passes, being bypassed. Water may flow into a burrow upstream and then re-enter the watercourse downstream, eroding the bank in the process.

Flood-banks and other river structures

Burrowing into flood-banks weakens their structure and renders them more susceptible to collapse and overtopping, or direct erosion in times of spate. The protected land behind, which might include housing, business/industry and farmland, is then vulnerable to flooding. Dams and burrowing can also cause a diversion of water flow and lead to erosion of riverbanks and the undermining of any associated water-side infrastructure, which could potentially include bridge supports, utility pipes, roads and tracks.

Canals

Beavers readily use artificial as well as more natural watercourses, so are frequently found in canal systems. There are cases of burrows damaging retaining banks of canals not reinforced by revetments, leading to leakage or localised failure. Similar impacts can occur in canals constructed to distribute water supplies for drinking, hydro-schemes and other purposes. The impact on the Crinan Canal is considered further in section 4.13.

Water treatment plants

If sewage settlement beds are in close proximity to a watercourse, they may be accessible to beavers and may overflow as result of any woody debris and dam-building. They contain reliable water supplies and are commonly surrounded by lush vegetation that may attract beavers.

Recreational facilities

Beavers will readily occupy environments that are regularly used for recreational activities such as swimming, leisure boating, sunbathing, jet skiing and canoeing. They can habituate to reasonable levels of disturbance, and tend to be more active at quieter times of the day when there is less human activity. Streams and ponds in places such as golf courses or parks can also provide suitable habitat. In most cases there are few conflicts, although dam-building, burrowing and tree-felling may sometimes cause problems.

Table 4.14.3 - Summary of potential interactions between beavers and infrastructure

Activity	Mechanism	Positive effects	Negative effects	Notes
Felling	Change in riparian woodland: felling		Felled trees have the potential to cause incidental damage when they fall on fences, power lines, buildings or transport routes. Although the frequency of these events is rare, if they occur they may be significant in terms of disruption, cost and risk to human wellbeing.
Other construction, e.g. burrows	burrowing		Burrowing can: Undermine roads, tracks and other structures causing subsidence Lead to instream channels causing weirs and fish passes to be bypassed. Cause bank erosion
Dams/pond creation	Change in hydrological processes on riparian an downstream habitat	Hydrological cycle and water flow maintenance: improvements in base flow, and protection of lochs, during drought periods due to increased water storage. Increase in water tables would lead to larger stock of water for drinking and non-drinking purposes (e.g. domestic use, irrigation, livestock consumption, industrial use) increased flood storage, and therefore a decrease in downstream flooding hydrological alternations may restore natural connectivity in wetland-loch systems water level rise in standing waters would be expected to increase the area of standing water habitat water level rise increases the volumes of standing waters, and greater volume may improve the capacity of a loch for dilution of nutrients and phytoplankton	Dam building can cause: Direct flooding of an adjacent road or access track Blocking of culverts, sluices and weirs and fish counters and fish passes Overflowing of sewage settlement beds as a result of woody debris and dam building Flooding of terrestrial land upstream/adjacent to lochs may result in deterioration of water quality through decay of vegetation and leaching of nutrients from soils Blocking of septic tanks outfalls

4.14.3.2 Assessment of the effects on infrastructure within the Beaver Policy Areas

The Knapdale beaver population would be expected to expand, with some likely further impacts on forestry infrastructure. This might include some flooding of tracks and other infrastructure resulting from beaver dam-building activity (including attempts to block culverts) and some occasional felling of trees onto tracks and footpaths. Animals will eventually start to move outside the forest itself, with increasing incidences of the types of impacts described above in the wider area. Continued monitoring would be required along the Crinan Canal, in particular to look for any burrowing into the canal embankments and for any beaver activity in the feeder lochs above the canal.

Tayside is a more populated area with a greater intensity of land use, and so the scope for beaver activity to impinge upon a range of land uses, and the associated infrastructure, is much greater. The TBSG have already recorded a variety of issues experienced by land managers and members of the public, many of which are summarised above. The expectation is that this pattern of impact will continue as the beaver population continues to expand throughout the catchment and beyond.

Roads and tracks

The flooding of a forest track occurred during the SBT at Knapdale, following the impounding of water behind a beaver dam across a minor watercourse.

On Tayside, beavers felled some poplar trees alongside a 200-m stretch of the A90 trunk road near Forfar, presenting a risk of some falling onto the carriageway. Transport Scotland arranged for trees gnawed by beavers to be cut down and the remainder to be protected with mesh fencing. Transport Scotland's A9 road dualling programme is currently underway and there is some early recognition of the need for future proofing for beaver activity as well as mitigation when there is a need.

At the Loch of the Lowes, an SWT nature reserve near Dunkeld in Tayside, there was beaver activity along a narrow strip of riparian woodland situated 10 m from the edge of approximately 1.6 km of a well-used road. Over the last few years at least two trees have fallen onto the road, presenting risks in terms of safety and obstruction. This led to a greater intensity of checking by ranger staff to identify any beaver-damaged trees, which were then felled. Fencing to prevent beavers gaining access to the trees was judged not to be a practical option.

At another Tayside site, 150 m of an access track to a small area of residential housing, next to a burn, was flooded during a period of high rainfall. The flow patterns of the burn had been affected by the raising of the water table on adjacent land caused by beaver dam-building.

Culverts, weirs, sluices, fish passes

A recent GIS-based analysis was done to examine the overlap of areas predicted to be less likely to be dammed by beavers, with existing anthropogenic watercourse structures. It was found that 78% of all culverts, weirs and fish passes in Scotland were at locations where dam-building was predicted to be less likely.

On Tayside there were two instances where dam-building activity had the potential to impede fish movement along fish passes. At one of these sites, the dam was built against a fish counter. The manager cleared the dam but then had to remove new debris from the counter every morning over a number of weeks after the beavers started to replace it. The debris prevented the counter from working and the manager eventually decided to remove it to discourage further dam-building.

Flood-banks and other river structures

Bank erosion was reported at four Tayside sites resulting from the redirection of water flows around a beaver dam. At one of these, access for farm machinery had been impeded. At another, there was a report of dam-building causing erosion next to a bridge, although there are no details of the type of bridge, size or scale of impact. Issues and potential issues were also recorded on five sites where there were beaver burrows in flood defence banks.

4.14.3.3 Mitigation Measures

There are a number of methods that can be used to protect infrastructure interests and in some cases it may be prudent to protect especially sensitive interests before problems arise. This is more achievable for small-scale structures, such as culverts under roads. The pre-emptive protection of larger scale structures that may be vulnerable to beaver activity, such as canals and flood-banks, would be more challenging. The scale and costs involved for revetment or reinforcement to prevent burrowing would be high. There would therefore be a need to identify and prioritise those structures that may be most vulnerable. Scotland could draw on European approaches to targeting sites for management, and GIS-based tools to identify areas where beaver activity is predicted to be more likely.

There are other issues that might affect small numbers of individuals, for example damage to ornamental trees and gardens. For these, and the more complex infrastructure issues described above, the development of an appropriate management strategy will be required. This will need to include guidance on management techniques (for both pre-emptive and reactive actions) and information on sources of advice and support. The effectiveness of beaver management in Scotland will increase over time as experience is gained and methods refined.

Section 5 also details the hierarchy of mitigation techniques that can be used to address impacts from beaver activities, including generic management and licencing approaches to more practical measures including those to address:

• Dam building activities
• Burrowing activities and
• Foraging activities

These mitigation measures apply to the potential negative effects identified in relation to beaver activity and infrastructure.

4.14.4 Beavers and Agriculture

4.14.4.1 How beaver activity affects agriculture

Since beaver distribution is always associated with running or standing water, the potential for beaver activity to have an impact on agricultural interests is limited to where they occur in the vicinity of streams, rivers, drainage ditches, wetlands, lochs or ponds. Once beavers occupy an area, they actively modify their surroundings to suit their needs, so they are able to use a wide range of wet environments, whether artificial or more natural.

Published information about beaver impacts on agriculture is limited. Impacts can arise from a range of beaver activities, including burrowing and canal construction to gain safe access to a lodge/den or to feeding areas; dam-building on smaller watercourses, ditches and pond outflows; blocking of culverts; direct foraging of crops; and gnawing and felling of trees of commercial value for food or construction materials. The extent and significance of the impacts will depend on the local topography, soil structure and hydrology, and the vulnerability of the affected interests. In general, there appears to be less concern about beaver activity in areas of low commercial value. The greatest concern arises where beaver activities affect areas of more intensive agricultural activity.

Beavers come into direct contact with agricultural land usually within about 20 m of watercourses, although very occasionally they have been found to range up to 150 m to gain access to a favoured food source. Indirect impacts on agriculture can be more extensive, such as those arising from the flooding or waterlogging of fields behind beaver dams.

Burrowing

Beavers will burrow into the banks of watercourses, as do a number of other species. All burrows, whether constructed by beavers or other species, can make banks more vulnerable to erosion during high water flows, especially in areas with more friable soils. The construction of canals by beavers may do the same. Damage to a river bank can result in the subsequent erosion of adjoining productive land and localised flooding of crops. There are some records of beaver burrows collapsing on farm land. Each individual burrow will be of a limited extent, but there can be many burrows along a stretch of river, and their collapse may potentially pose a hazard for walkers, livestock and machinery operations, although few occurrences of actual harm have been recorded. These effects would have cost implications, in particular where they impede farming operations that have strict time constraints, such as during harvesting.

Burrowing may be a particular problem where it occurs in flood-banks protecting intensive agriculture on low-lying flood plains. The more extensive the floodplain, the more vulnerable it is to the consequences of any flooding caused by the failure of a flood-bank. Flooding can inhibit or prevent cultivation and damage or destroy crops and grazing for livestock. Flood-bank failures arise in the absence of beavers, including as a result of burrowing activity by other species, although beaver activity can render them more vulnerable because the entrances to beaver burrows are usually below the water level. This means that during high flows there can be a build-up of water pressure within a burrow, which is then applied to the internal structure of a flood-bank. This can cause a collapse of the soil above the burrow, leading to the possible flooding of protected farm land behind it.

Although burrowing can be completely prevented by the installation of 'hard' reinforcements such as stone-filled gabions, large rocks, sheet/mesh metal or concrete piling, these options may be neither commercially viable nor ecologically desirable along extensive lengths of watercourse.

Dam-building

Dam-building by beavers on running waters, or at the outflow of a pond, loch or reservoir, will raise water levels, but will be of little concern in many situations. However, it may cause direct waterlogging of adjacent farm land, and sometimes the erosion of banks. Beaver canals may also radiate from beaver ponds to extend their feeding range into the surrounding farmland. If a dam is at a pinch point and some water level rise is acceptable, the agricultural impacts may be managed and limited through the installation of a water flow device or the cutting of a notch into the dam. Beavers may also block drainage culverts using woody material and other vegetation, and can cause localised flooding of crops and farm access infrastructure.

The most significant impacts of dam-building activity on agriculture are likely to occur on intensive arable land on fertile flood plains, where cultivation is reliant upon an extensive network of drainage ditches and field drains. In these situations the shallow gradients present a very low tolerance threshold for any rise in the water table before the drainage system fails. Such failure can cause the direct damage of crops through flooding or waterlogging, and the inhibition of cultivation across a large area well beyond dam-building sites. As a consequence, checking for and managing beaver dams may become a regular activity for land managers, with attendant costs in terms of time and machinery. Where inundated soil has been fertilised, this may also result in a significant increase in nutrient loading of waterbodies. The use of techniques such as notch weirs or flow devices is not always effective in these situations, and the removal of dams is usually followed by rapid reconstruction if the beavers remain. Effective mitigation is difficult and farmers, and farmers' organisations, have expressed the view that the presence of beavers is not appropriate on these types of farmland.

Feeding on crops

Beavers are highly adaptable and may quickly exploit new food resources. Agricultural crops may be eaten in close proximity to watercourses. Feeding on a wide variety of agricultural crops has been recorded, including sugar beet, maize, cereals, oilseed rape, peas, potatoes, asparagus and carrots. In most cases the scale of crop loss is not commercially significant and usually confined to an arc of about 10 m in radius extending from the water access point. There are a number of fencing techniques to help minimise this, including the use of temporary electric fencing.

Tree- and shrub-felling

Felling of woody material for food or construction materials can be an agricultural issue for a variety of reasons. Felled trees can obstruct farm roads and access tracks, damage fences and block drainage ditches. There can also be a direct loss or damage to orchard trees, soft fruit bushes, landscape trees, farm woods and shelter belts, and the potential for damage to hedges. Protection measures include fences, tree guards and protection paint.

Table 4.14.4 - Summary of positive and negative effects of beaver activity on agriculture

Activity	Mechanism	Positive effects	Negative effects	Notes
Felling	Changes in riparian woodland		Felled trees can obstruct farm roads and access tracks, damage fences and block drainage ditches. There can also be a direct loss or damage to orchard trees, soft fruit bushes, landscape trees, farm woods and shelter belts, and the potential for damage to hedges.
Felling and constructions	Changes in amount/diversity of woody material in watercourses	Increased number of wood jams, resulting in attenuation of flow and lowering of downstream flood risk and improvements in water quality as fine sediments settle in areas of slower flow	Increased number of wood jams, so a possibility of localised floodplain inundation and impacts on land use
Other constructions, i.e. burrows	Burrowing		Damage to a river bank can result in the subsequent erosion of adjoining productive land and localised flooding of crops. Burrowing may be a particular problem where it occurs in flood-banks protecting intensive agriculture on low-lying flood plains
Feeding	Feeding on specific terrestrial herbaceous and aquatic plant species	Clearance of vegetation that is acting as a barrier to water flow may restore flushing rates in standing waters and prevent backing-up and consequent flooding	Feeding on crops in the riparian zone
Dams/pond creation	Change in hydrological processes on riparian and downstream habitat	Hydrological cycle and water flow maintenance: improvements in base flow, and protection of lochs, during drought periods due to increased water storage. Increase in water tables would lead to larger stock of water for drinking and non-drinking purposes (e.g. domestic use, irrigation, livestock consumption) increased flood storage, and therefore a decrease in downstream flooding water level rise increases the volumes of standing waters, and greater volume may improve the capacity of a loch for dilution of nutrients and phytoplankton Carbon sequestration through wetland creation	Increased flooding of riparian zone and beyond, so potential impacts on land use such as cultivated crops, meat and dairy products and timber (indirect impacts due to localised flooding), plus infrastructure (direct impacts due to localised flooding of roads and tracks, blocking of culverts, weirs, fish passes, etc.) With increasing loch volume, water retention time increases, flushing rate decreases and nutrients and phytoplankton are retained for longer within the loch. Beavers may also block drainage culverts using woody material and other vegetation, and can cause localised flooding of crops and farm access infrastructure.
Other: Indirect habitat creation/restoration initiatives as result of beaver presence	Beaver used to promote opportunities for riparian and freshwater habitat creation/restoration	Presence of beavers may act as an incentive for greater investment, management and monitoring. This could those related to the restoration and management of riparian woodland and wetlands, which would benefit a range of bird species

4.14.4.2 Distribution of the prime agricultural land resource within the Beaver Policy Area

Knapdale

There is no prime agricultural land in the Knapdale Beaver Policy Area although there is other improved grassland present.

Tayside

The distribution of prime agricultural land in relation to core beaver woodland habitat is detailed in map28 below and reproduced as A3 size in Appendix 1.

Within the prime agricultural land area beaver activity and impacts will be restricted to some freshwater features and the immediate riparian habitat.

Map 28 - Tayside prime agricultural land and potential core beaver woodland

4.14.4.3 Assessment of the effects on agriculture within the Beaver Policy Area

Given the nature of the habitat on which beavers depend, i.e. riparian broadleaved woodland and shrub within 50m of freshwater, there are unlikely to be significant direct impacts on prime agricultural land, i.e. land capability classification Class 1 and Class 2. However, there are likely to be a number of indirect and locally significant effects, some of which have been reported and are detailed below.

Knapdale

At present, there is a very limited opportunity for beavers to come into contact with agricultural activity in Knapdale. There are some small areas of grazing within Knapdale Forest but the main land use is forestry. If beavers were to remain at Knapdale, and the population reinforced, then it is anticipated that the animals would start to colonise along freshwater networks in the medium to longer term, some of which borders agricultural land, primarily grazing. Inevitably there is likely to be some increase in management issues related to agricultural activity and impacts of local significance to individual farmers, although probably not to the extent that might be expected on Tayside.

Tayside

In Tayside there is already considerable beaver presence in agricultural areas. Between early 2012 and late 2014 during the course of the TBSG studies, the beaver range continued to expand within the catchments of the Rivers Tay and Earn, and colonisation is expected to continue into the future, ultimately occupying most of the suitable habitat. Colonisation of adjacent catchments is also anticipated if there is no intervention. This will inevitably bring them into further and increasing contact with riparian farmland. The incidence of agricultural conflicts would increase with particular concern for the management implications for the intensively drained and flood-bank-protected arable farms such as those on the floodplains of the Rivers Tay and Earn.

The TBSG was informed about 56 beaver sites across Tayside, 28 of which (50%) reported negative impacts. The majority of negative impacts were recorded in the more intensively farmed lowland areas at sites directly adjacent to watercourses. The types of impacts recorded included burrowing into banks and increased erosion and bank collapse; crop foraging (wheat, barley and carrots); and dam-building and associated erosion and flooding. Of those experiencing negative impacts, 70% reported a financial cost.

One particular lowland farm on Tayside had 13.8 km of actively managed burns and drainage ditches on 445 ha of arable land. Between September 2013 and November 2014, 32 dams were built, or in the process of being built, by beavers. Dam-building occurred in seven sections of burns and drainage ditches. The dams were regularly removed by the landowner, mainly by hand, to avoid potentially serious impacts on field drainage. Dams in two of the seven sections were rebuilt within one day of removal, and at another two sections they were rebuilt a week after removal. Before beavers started to occupy the area, farm staff carried out walked inspections of burns and ditches twice a year to monitor for blockages. Following the arrival of beavers, the frequency of inspection was reported as increasing to once a week, requiring one day of work on each occasion. Approximately four hours per week was spent removing dams.

Issues and potential issues arising from beaver burrows in flood defence banks protecting intensive arable land were recorded on five sites on Tayside. At two sites, beaver burrowing activity had resulted in several breaches costing £5,000 to repair in 2013, and flood debris deposited on the land behind. A further breach was reported in early 2014. No breaches were recorded on the other three sites, but concerns were raised about increased risk due to burrowing activity in the area. In all cases, the flood-banks were within 10 m of the river and the burrow entrances were below the water level, resulting in a greater risk of erosion and collapse during spate flows.

4.14.4.4 Mitigation Measures

The Scottish Rural Development Programme ( SRDP) 2014-2020, Pillar 2, Agriculture Environment and Climate Scheme ( AECS), promotes land management practices which protect and enhance Scotland's natural heritage, improve water quality, manage flood risk, mitigate and adapt to climate change, improve public access and preserve historic sites. (has the aim of encouraging sustainable economic growth in Scotland's rural areas. Its priorities include supporting agricultural business and protecting and improving the natural environment).

There are several management options and capital items available to encourage land managers to create new habitat and manage existing areas of farmland likely to be most affected by beaver activity. Agri-Environment Climate Scheme funding could be considered (for management) in the following areas:

• Water margins in arable fields
• Water margins in grassland fields
• Grass strips in arable fields
• Conversion of arable at risk of flooding or erosion to low-input grassland
• Wetland management
• Restoring (Protecting) River Banks
• Small-scale Tree and Shrub Planting

In addition, the Greening element of Pillar 1, Basic Payment Scheme, requires farms with a certain % of arable ground, to manage 5% of this area as an Ecological Focus Areas ( EFA). The main aim of an EFA is to improve biodiversity and may potentially include the management of riparian buffer zones. There are six EFA options to choose from and fallow land, buffer strips and field margins could be adopted by land managers on land affected by beaver activity.

Section 5 also details the hierarchy of mitigation techniques that can be used to address impacts from beaver activities, including generic management and licencing approaches to more practical measures including those addressing:

• Dam building activities
• Burrowing activities and
• Foraging activities

These mitigation measures apply to the potential negative effects identified in relation to beaver activity and agricultural operations.

It is recognised however that mitigation for burrowing into flood banks may not be readily practicable and trialling of different deterrent techniques is required. SNH will work with the farming community to undertake trials. It is also recognised that there may be a desire to exclude beavers from some areas of prime agricultural land in the long term, and the efficacy of such an approach will also need to be trialled.