An outline plan of scientific work is proposed for the Trust to consider.
The aim of the Plan is to acquire the knowledge necessary to manage the fish populations of the Flow Country and the fisheries they support. The target should be to manage in the best practicable fashion, taking account of the wider ecological and land management settings in which the fish populations exist. The Plan will strengthen the basis on which to argue for the interests of the fisheries and, when necessary, to suggest management actions to improve fisheries or compensate for adverse effects.
An initial five year plan is proposed, recognising that a substantial amount of work is required to gain a sufficient understanding of all the main issues. Furthermore, many changes are long-
The suggested approach is to support and fund a modest autonomous programme, collaborate with others on projects of mutual interest and, more generally, encourage and facilitate activities of the scientific community in researching those aspects of the Flow Country that impinge on its lochs and rivers. The Plan therefore ought to include scope to respond to emergent issues or opportunities when they arise.
At this stage, the main up-
SCIENCE PLAN FOR THE TRUST
Alan F. Youngson
A provisional list of proposed projects is discussed in what follows. For ease of reference they are listed below. All the projects link in various ways to the five themes listed above.
1. STRATEGIC ACQUISITION OF DATA.
Public bodies such as SEPA, SNH and Marine Scotland Science (MSS) collect data for all the Scottish rivers, including those of the Flow Country. Notably, SEPA monitors river height across a range of locations and has seven gauging sites in the Trust’s area that continuously monitor flow (1). In yet other cases, data is collected in response to specific local needs. For example, SNH obtains electric-
The following projects cover important areas. The resources required are likely to be beyond the Trust’s reach but they could be achieved by collaborating with scientists working for other organisations with shared interests.
1a. Stream temperature. A trend towards increasing stream temperature is likely to become increasingly important in coming years. High temperatures have the potential to affect both juvenile and adult salmon, as well as other fish and non-
MSS is initiating a programme to monitor temperatures across the Scottish rivers, to find out how the response to warming varies among locations and to determine why this is. The Thurso is listed among the chosen set of Scottish rivers because of its location and characteristics. The Trust should facilitate work like this. It should also respond by contributing fish data of the type obtained for the Caithness rivers in 2013 in order to aid interpretation by linking data on fish performance with temperature.
However, MSS is a national organisation and its remit is correspondingly wider than the Trust’s. If necessary, the Trust should therefore take steps to augment MSS’ collection of temperature data in order to ensure that its own requirement for local information is met.
The aims of this programme would be to establish the magnitude, frequency and distribution of episodes of high temperature and to determine which locations and types of location are most susceptible -
1b. Stream chemistry. Many aspects of land management have the potential to adversely affect stream chemistry to the detriment of fish and other species. In the Flow Country catchments, forest clearance, re-
Again, however, the Trust should encourage and facilitate the work of other parties in this area. In addition, because of its local presence, the Trust can play a special role in obtaining water samples for analysis. For example, strategic sampling during the brief periods of floodwater is important because many changes in water chemistry become particularly evident under these conditions. This form of sampling is sometimes best organised locally by people on the ground who are in a position to respond quickly to transient events.
1c. The smolt migration. Although the Trust’s remit is effectively restricted to juvenile salmonids and to fresh water because of the immense resources required to perform marine research, there are aspects of the transitional phase between freshwater and marine life of juvenile salmonids that are important and potentially accessible. These relate to behaviour at smolting and during the early stage of marine life and they are particularly important in the context of marine renewables development.
First, the migration of smolts and their entry to the sea is considered to take place around May. However, this timing is only generally defined and although river managers gain an impression from their observations, no specific information exists for the Flow Country rivers. Knowledge of timing is necessary for mitigation, for example, during construction works; potentially disruptive operations such as pile-
Secondly, the Pentland Firth and its environs will be central to marine renewables development because the extreme sea conditions that prevail there represent an intense and relatively consistent source of power. Indeed, tidal flows in the Firth are so rapid that they must totally dominate the movements of any young fish that attempt to move through because the speed of the currents is so much greater than the swimming capacity of the fish. As is well-
A glance at the map, however, suggests that smolts leaving the various Flow Country rivers will not be affected in the same ways or to the same extent. Thus, for example, smolts leaving the Thurso or Naver need not enter the Pentland Firth to make their journey, especially if they initially head westwards and close inshore. However, for smolts leaving the Wick or Berriedale, for example, the risks appear to be much greater because the Pentland Firth is an obvious candidate route north and westwards towards the feeding grounds. These same considerations are likely to relate to any of the developments that are planned and to any future proposals because, perhaps paradoxically, the proximity of the Flow Country rivers to the developments increases the likelihood that their migrants will be differently affected. Unfortunately, there is no information on the actual routes used by smolts leaving the Flow Country rivers or, indeed, any other rivers, and this is a critical knowledge gap.
MSS is currently planning a programme to study the outwards movement of smolts in coastal waters. Although the details of this work have not been finalised the approach is likely to centre on using arrays of listening stations to follow smolts tagged with acoustic transmitters. The resources required to mount such an operation are very large and it is therefore unlikely that any programme will be sufficiently extensive to generate the local information the Trust needs.
Active tracking – by which smolts tagged with acoustic transmitters are followed from a boat using a hand-
Because of the importance of this work and its difficulty, the Trust should seek collaboration, making facilities and fish available and supporting the specialists who might carry out such work. Active tracking has the potential to provide an understanding of the scope for interaction between smolts and renewables, particularly if the work is repeated across a representative sample of the Flow Country rivers. If such studies were available they would pinpoint particular areas of concern for the first time and eliminate or downgrade others. This, in turn, would permit a more informed strategic approach to consideration of interactions between fisheries and renewables than is currently possible.
1d. Genetics of salmon and trout. It has become increasingly evident over the past three decades that populations of salmon and other fish species are genetically distinct. This has important knock-
In fact, some of this knowledge is not new but rather a re-
Genetic analysis is a specialised technical area and, once again, outside the Trust’s reach. Nevertheless, the Trust should encourage and foster such work. In this spirit, for example, more than 1000 scale samples from salmon obtained in the course of the 2013 electric-
2. NEW FISHERIES DATA.
It is important to characterise the salmon runs each year because the number of adults and their size determines the number of eggs deposited each year and this is the starting point for the new generation of young fish.
Egg numbers are linked to fry and parr numbers and these, in turn, are linked to smolt numbers; smolt numbers are then linked to the size of the next wave of returning adults and so on. Because all the life stages are interlinked, it is possible to glean useful information on the status of populations at any stage of the life-
In recent decades, levels of marine mortality have been unusually high and the resulting decrease in the number of fish returning to the coast has restricted catches and spawner numbers. It is outside the scope of the Trust to address questions around the causes of high marine mortality and, in any case, these matters are being considered by MSS and other bodies.
However, the status of salmon populations can be measured in rivers, as juveniles or as adults. This can be done in a number of ways. None is an infallible guide to population status but each is of value in pinpointing issues for action. Taken together assessment of fish and fisheries in the Flow Country rivers will provide the best available picture on the local scale consistent with the Trust’s remit. Getting good Information on fish and fisheries will form the backbone of the Trust’s work.
The following projects will provide basic information on fish abundance and are probably achievable using only the Trust’s resources.
2a. A juvenile survey programme. Twenty-
In future, survey work in the Caithness rivers should be repeated to test and consolidate findings made in 2013. This will confirm the validity of the approach. It will also allow examination of variation in fish recruitment, growth and performance between years. The Caithness programme should be extended to cover the Flow Country rivers in general. These measures will provide a comprehensive and detailed picture of the fish populations that the rivers support, for the first time.
In addition, the Trust should try to ensure that electric-
The outcome of these surveys will be a definitive account of the contemporary status of the main target species – salmon -
After the initial phase, a strategic review of the electric-
2b. Examination of adult catch data. National catch data is already compiled each year by MSS and split down for the formal Fishery Districts but a subsidiary analysis on a river-
The MSS analysis does not currently include measures of how fishing effort or catch-
In particular, using crude measures of catch-
Additionally, all the Flow Country rivers are occasionally beset by factors that reduce catches by hampering both fish and fishermen -
Expert information on adverse effects on angling success is potentially available from river managers on a river-
2c. Tagging or photographing released fish to estimate stock size. The link between stock size and catch, or catch-
Alternatively, it may be possible to identify fish captured for a second time from a library of photographs. Young salmon and ferox trout, for example, show patterns of black spots (constellations) on the face which are variable, permanent and unique to individuals. Adult salmon carry fewer spots than young salmon or trout but sufficient to make the identification method worth testing. Therefore, if captured fish were photographed before release it may well be possible to identify them again among fish caught and photographed at a later date.
All that would be required to attempt this is a digital photograph of one side of the face taken from directly above and about 0.5m distant, using a mobile phone or any better camera. This photograph would then be compared with all the fish caught later on in the season to match facial spotting patterns in fish caught for a second time. Measurement of the fish (from tip of snout to fork in tail using a flexible tape measure) would simplify matters by allowing comparison to be restricted to the smaller set of photographs of fish of about the same length.
The procedure would therefore be to measure each fish, obtain a single standard photograph of the left face (raised out of water), specify date and place of capture and confirm that the fish was released. Even more information (unique scars, marks etc) could be provided by also including a full length shot of the left flank. This approach to identification has not been attempted before on adult salmon but it is worth exploring because the photographic method is rather simple. It would also obviate the need for tagging and special training and it would eliminate any logistical problems caused by loss of tags.
The information resulting from either identification method (tagging or photography) could be used to make due allowance for repeat capture of the same fish when considering catches as an indicator of relative stock abundance. In addition, the same information could be used to estimate exploitation rate and therefore to estimate the true total number of fish in the river. This value is usually unknown but it is absolutely crucial for a consideration of whether the number of adults at spawning time matches the capacity of the river to hold young fish.
It may also be possible to establish the sex of fish from photographs, allowing the total number of females to be separately examined. Again, this is potentially valuable information in relation to assessing levels of spawning and egg deposition.
3. CONSOLIDATION OF EXISTING FISHERIES DATA.
Extensive information on the fisheries and ecology of the Flow Country rivers is available from a wide variety of sources. As yet unidentified sources probably also exist. Some of the readily available sources have a strong historical aspect which it is important to try to understand in order to place the present status of the rivers and their fisheries in a wider context.
Many sources of information have been collected and interpreted in contexts that are not particularly related to fisheries. For example, SEPA has interpreted electric fishing data in the context of the water resource according to its specific remit; SNH has done the same in the context of site condition monitoring of the salmon SACs for rivers like the Thurso and Naver. The Trust should search for and consolidate available sources of information. The data should be brought together and re-
Both the following projects are achievable using only the Trust’s resources.
3a. Analysis of catch data. MSS has formal catch data for salmon and sea-
Summaries of the fisheries reaching even further back are available -
3b. Electric fishing survey data. Although a new start was made with the 2013 survey of the Caithness rivers, it is important to note that extensive survey data exist for previous years for most of the Flow Country rivers. These data should be located and consolidated. They should also be integrated and re-
4. INVENTORY OF RESOURCES.
In order to plan the Trust’s work, it will be necessary to identify and take account of information that already exists in order to target effort and avoid duplication. In many cases, the information is dispersed but it should be identified as far as possible and compiled for reference.
All the following projects are probably achievable using only the Trust’s resources.
4a. Ancillary environmental and biological data. Data for the Flow Country’s rivers and lochs -
4b. Previous science projects on Flow Country rivers. The Flow Country rivers have undoubtedly received some attention from scientists In the past but, again, this work is likely to be dispersed. Frost, for example, worked on the feeding ecology of young salmonids in the Forss and published the results as long ago as 1950. In recent years, attention has increasingly focussed on the ecology of the peatlands and this new emphasis is likely to continue. All geographically relevant studies of the Flow Country rivers and their environs should be identified, complied for reference and, thereafter, continuously up-
4c. Trout lochs. Although salmon dominate the Flow Country fisheries, the area contains a myriad of trout lochs. Some support vigorous fisheries and are well-
An inventory of lochs should therefore be compiled from contemporary fishery sources and any historical sources that can be identified. For some remote lochs, exploratory fishing may be required to document their fish populations -
4d. Woodland in stream margins. Contemporary forestry practice emphasises the necessity for wide buffer zones along stream and river margins on both aesthetic grounds and as a functional buffer to protect stream chemistry from the potentially adverse effects of forest management. Planting of buffer zones with native trees is often proposed although local species and types are not generally available for use in the extreme North.
Natural woodland is sparse in the Flow Country although this was probably not always the case. Native woodland is currently restricted to the few locations that are not readily accessible to sheep or deer. Nevertheless, steps should be taken to identify relict native or natural woodland where it exists and to establish the range and composition of species present. The upper and eastern parts of the gorge near Dirlot Castle on the Thurso, for example, contains only rowan and birch although planting associated with the old cemetery nearby appears to have affected the tree species in the north-
A drift towards naturalistic planting will probably develop, driven by increasing recognition, as for other species, of the importance of conservation genetics in ecology and woodland management. Characterisation of native, stream-
In a slightly different context, it is widely predicted that increasing water temperatures will become a potentially adverse feature of northern rivers. Partial shading by marginal tree-
More generally, the Trust should expect to represent fishery interests in the contexts of structural and engineering works in or near rivers. In many cases, these are expected to comply with official guidance designed to protect fisheries. However, occasion lapses occur or maintenance issues may arise with, for example, culverts. The Trust and its members are well-
In the same way, land-
The projects listed above are the result of an attempt to provide a balanced programme of work for the Trust. Some projects are listed because they are crucially important for the Trust’s interests. Others are eminently achievable although possibly of lesser importance. Yet others are listed because they offer scope for widespread participation by anyone who is sympathetic to the Trust’s aims.
The intention is that this document will become the Trust’s first Science Plan. Since the issues will quickly become clearer as work progresses, the agreed initial version of the Plan should be reviewed after one year and re-
© Alan F. Youngson
© 2019 FCRT / ALASDAIR OGILVIE
1. Strategic acquisition of data.
1a. Stream temperature.
1b. Stream chemistry.
1c. The smolt migration.
1d. Genetics of salmon and trout.
2. New fish and fisheries data.
2a. A juvenile survey programme.
2b. Examination of adult catch data.
2c. Tagging released fish to estimate stock size.
3. Consolidation of existing fisheries data.
3a. Analysis of catch data.
3b. Electric fishing survey data.
4. Inventory of resources.
4a. Ancillary environmental and biological data.
4b. Previous science projects on Flow Country rivers.
4c. Trout lochs.
4d. Woodland in stream margins.
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