DUNBEATH WATER RISK ASSESSMENT
Having introduced the background, and before formulating the river plan objectives and implementation, it is good practice to consider briefly the real and potential risks to the ecology of the Dunbeath Water and its catchment. These risks should be considered when formulating a river plan of this nature:
Water quality and flow
Droughts and floods
Acute and chronic pollution events
Silting, erosion and landslip
Surrounding land management, agriculture and forestry
Disease and parasitism
Overfishing, poaching and anthropomorphic disturbance
Farm salmon introgression and hybridisation
Poor planning, damaging management and human neglect
Marine habitat and fishery at sea
Implementation of the River Plan
1. Maintaining and improving the conservation status of the river and its habitat
Past and current management by the owners, their employees, SNH and SEPA mean that high standards of ecological health are maintained through voluntary and/or mandatory mechanisms. The plan expects SEPA hydrological monitoring to continue, thereby protecting against chronic or acute pollution, silting and adverse flow. In this section, the overall plan is therefore to continue current practices as described in the Background on Recent Management.
The owner and local management team proposes to maintain the physical structure of the river, with traditional hatches, croys and bankside building or repair. In addition, any new barriers or obstructions will be removed to protect flow, migration and erosion.
Surrounding natural vegetation through the upper and lower reaches will be maintained and, in the lower reaches, any risks of light pollution will be assessed.
The bailiff and his team, in conjunction with the Angling Club, will monitor poaching (currently at a seemingly very low level), predator numbers, as well as surveying for non-
2. Improving ecological understanding of the river, and the biology of its salmon
The river is currently well characterised hydrologically by ongoing SEPA data gathering (Appendix 1), and we encourage that continuation, with engagement by the Dunbeath management team with the data and analyses.
Having instigated SFCC electro-
Detailed rod catch records will be maintained, to include measures of size and whether salmon, grilse or sea trout. The rod catch has shown extremely healthy growth since 1997, and the trajectory remains set at a linear increase. We plan to monitor the statistics in order to assess whether rod catch saturation has been achieved following all the improvements to the river as identified in the Recent Management section, or whether further growth in the catch can be achieved while remaining sustainable. In addition to the rod catch data, anglers monitor the presence of disease, and invasive species, especially the presence of farm salmon in the system. Escaped farm salmon present a recognised risk to the genetic integrity and health of wild populations, because farm gene introgression can disrupt locally adapted populations. The huge growth in aquaculture is responsible for a very large number of escapees from sea nets, and it is important that all rivers monitor the presence of farm escapees so that any problem can be reported. Anglers are asked to report such incidents to the River Bailiff, and numbers will be reported through the CDFB and RAFTS.
Anecdotal records indicate that spawning redd distribution and occupation can show marked variation between years. From 2013, we will identify 10 recorded spawning sites across the river, and begin data collection of spawning adult presence-
A recognised bio-
There is currently no formal water level mark, so we will implement a level marker in the river, near the Bridge Pool, to quantify flow.
Through the hatchery program (see 4.), we will collect and store DNA from a small sub-
Although currently speculative (because of cost), we aim to install a fish counter in the lower Dunbeath Water. The counter will not only allow for a sustainable yield to be calculated based on more direct evidence, but will also improve our understanding of salmonid ascent and descent behaviour in a Highland spate river. Our aim is to seek opportunities for funding such a venture, allowing the Dunbeath Water to be a model system for Scottish spate rivers, so that migration data in relation to season, year and flow can be tracked and analysed.
3. Achieving a sustainable yield of salmon from the river
Although the River Plan seeks to understand, maintain and protect all aspects of the hydrology and ecology of the Dunbeath and its catchment, salmon are a keystone species in the river. Salmon populations are ecological lynchpins in the system, and also underpin the socioeconomic value of the river to the local and wider community. Thus, we also focus on managing a sustainable yield in this plan. Achieving this yield is largely a consequence of current management already in place, in addition to ongoing or new plans identified in 1. 2. and 4. (below). On top of these structures, we aim to implement additional measures, and propose these in formal consultation with experienced salmon bailiffs and experts throughout this plan. We therefore plan to invite consultation visits by Peter Quayle and Sir Michael Wigan from the Helmsdale Management Board in 2014, to review the plan, walk the river, and conduct open discussion on the past, current and future of the Dunbeath Water.
The historical Spring run of salmon in the Dunbeath has declined, which presents an opportunity to target this seasonal niche for improvement in number. Apart from close monitoring of running fish early in the season, we will implement moves to reduce the killing of early-
In addition to targeted improvements to the spring run, we will maintain (in the absence of a fish counter), observational assessments of salmon abundance through the season, and regulate fishing pressure accordingly, with particular regard to catch-
During periods of extreme drought, we will allow the hatches in the headwater lochs to contribute to additional flow, thereby reducing extremes that create additional pressures on fish in the river from reduced flow including low oxygen, rising water temperatures, and overpopulation of reduced numbers of holding pools.
During drought periods, and also during the spawning periods, we will attempt to reduce human disturbance to the river in these areas by managing, where possible, visitors away from more vulnerable areas.
4. Maintaining a small restocking program using native Dunbeath broodstock, and testing its effectiveness for achieving a sustainable salmon harvest
5. Using aspects of the management plan for environmental education and awareness
Finally, we plan to use aspects of the Dunbeath Water as an educational resource. The plan and ongoing reviews (and further plans) will be published on the web through the Dunbeath Estate website, the CDFB, and the Flow Country Rivers Trust. We plan to involve the local community, especially school children, in hatchery demonstrations and guided river walks, centred around the fascinating life cycle of Salmo salar, and the ecological and socioeconomic importance of rivers like the Dunbeath Water.
Monitoring and Review
The River Plan will be progressed through twice-
The Dunbeath has been annually stocked with fry (up to 30,000 fed fry p.a.) under the current ownership since 1997, and records show that restocking with unfed fry took place historically. Despite questions about the success of salmon restocking, it is possible that this management has contributed to the correlated and significant annual improvement in salmon rod catch since 1997. In 2009, the owners invested in their own small hatchery program in the basement of the Dunbeath Mill which is adjacent to the lower river next to the Mill Pool, utilizing the old mill lead water supply. In times of drought and low water, flow is maintained through the hatchery tanks using recirculation.
We plan to maintain the hatchery and restocking because we have no evidence that the practice has any detrimental effect on the Dunbeath system, and indirect evidence from rising salmon catches that restocking has improved salmon numbers. Implementation of a local hatchery allows the use of native Dunbeath salmon broodstock, and careful and specific restocking in line with troughs in adult spawning, and in areas informed by surveys where spawning activity has been reduced in any one season, and where ideal juvenile habitat exists. In addition, the hatchery acts as an important reservoir for eggs and fry in seasons experiencing exceptionally high or low flows.
The hatchery is managed by Mac Young, the senior river bailiff, who consults with experienced operators on the nearby Helmsdale, Thurso and Wick rivers. Broodstock are taken at the end of the fishing season and maintained in large holding tanks before stripping. The aim is to strip 5% of the estimated population of fish that spawn naturally in the system, which usually amounts to approximately 10 hen fish per annum depending on spawning activity, rod catch and adult surveys for the season.
Adult broodstock will be maintained in large 5,000 litre circular holding tanks (3m diameter, 1m water depth) and checked weekly for ovulation and fungal disease. Signs of fungus can be managed using saltwater wash. Since implementing these practices, in the last two years no adults have been lost to disease and all were successfully stripped and returned.
Ovulating hens will be stripped (following anaesthesia), and fertilized by milt from two to three cocks. All adult broodstock are allowed to fully recover, and then released to a known holding pool in the river within 1km of the estuary. Fertilised ova are then raised in hatchery trays fed by river water at natural temperatures. Any dead eggs are picked on a weekly basis. After hatch, alevins are transferred to 1m tanks, with 3,000 fish per tank, to get them through the difficult stage onto feeding. Once successfully through, fry are moved to 2m diameter tanks with plastic refugia.
Currently, our hatchery practice achieves high success rates: 99% of stripped eggs are fertile and successfully hatch; if retaining them instead of restocking, we then lose 10-
The restocking strategy will be to return unfed fry to prime juvenile habitat where surveys of spawners for that year have shown reduced activity. Electric fishing surveys of sites that have been previously stocked show healthy numbers of fry and parr present. Fry are returned to the river in April, over a three to four week period (commensurate with when different groups hatched). We will restock using genetically mixed families at any one site, thereby avoiding the creation of genetic structuring which could lead to inbreeding. Fry are carefully introduced along a suitable stretch of juvenile habitat, spreading out the introduction at a typical rate of 2000 fish per km of stream section.
In 2013, DNA was sampled from all adult broodstock through a small fin biopsy stored in ethanol for two purposes. First, this allows the creation of a Dunbeath salmon genebank, which could provide a useful historical resource in the future. Second, we plan to continue this for >5 years, and then genotype returning fish at a suite of hypervariable microsatellite loci, which will allow us to determine the effectiveness of the hatchery for producing return spawning salmon. There is considerable controversy as to whether hatcheries harm or help wild salmon populations, but the direct evidence is lacking. We propose to use the Dunbeath Hatchery not only as a resource and reservoir for restocking, but also to test the effectiveness of hatchery restocking in general. We plan to record all details of the hatchery restocking, so that the genotyping results which record success rates can be interpreted in relation to hatchery practice, and therefore be applied to other salmon hatchery and restocking programs as well as that on the Dunbeath Water.