Case study:River Dee
Project overview
| Status | Complete |
|---|---|
| Project web site | http://www.riverdee.org.uk/welcome.asp |
| Themes | Economic aspects, Habitat and biodiversity, Hydromorphology, Land use management - agriculture, Monitoring, Spatial planning |
| Country | England |
| Main contact forename | Nick |
| Main contact surname | Elbourne |
| Main contact user ID | User:NickRRC |
| Contact organisation | River Restoration Centre |
| Contact organisation web site | http://www.therrc.co.uk |
| Partner organisations | River Dee Trust |
| Parent multi-site project | |
| This is a parent project encompassing the following projects |
No |
Project summary
Obstructions to fish migration on the Dee:
Since 2007, the Dee DSFB and Trust have eased or removed 27 manmade obstructions to fish migration from the river Dee's tributaries.
the aim is simple: To allow fish to gain access to their natural spawning grounds.
These manmade obstructions include weirs, bridges, vehicle fords and culverts. Some are completely impassable to fish, others are impassable in low flows; the latter can delay migration and have a knock-on effect of making fish more vulnerable to predators and stress.
In 2007 we assessed all the known manmade obstructions to prioritise them for easement or removal. For example, removing an obstruction that is on a tributary with poor habitat for salmon, or that is located close to the headwater source, will offer a lot less potential for increasing fish production than removing an obstruction that is low down on a prime-quality tributary.
The physical work of tackling the obstructions is often supported by obtaining external funding, particularly from SEPA's Water Environment Fund and from the EU LIFE fund. The physical works are completed by contractors or in many cases by our staff.
In 2014, the largest manmade obstruction was eased by installing a fish pass to the face of the Culter dam and two weirs further upstream in the Culter tributary were eased
Monitoring surveys and results
On 3rd October 2014 the first salmon ascended the Culter Dam in over 250 years, thanks to a fish pass we installed on the dam just days earlier funded entirely by businessmen Martin Gilbert and Stewart Spence. This dam, at Peterculter, is the largest man-made obstruction on the River Dee.
- 2014 Season: Numbers up the fish pass to date (June 2015): 43 Salmon 69 Sea trout
Why install a fish pass on the Culter?
The fish pass has opened up 76 miles of habitat in the previously inaccessible Culter burn for migratory salmon and sea trout to re-establish natural populations in.
Only the lowest one mile of burn is below the dam and so accessible to salmon and sea trout. The spawning and rearing habitat in this part of the burn is fully utilised, resulting in high juvenile fish densities. High juvenile fish densities mean lots of competition and higher mortality rates. Creating more rearing habitat for juveniles will result in lower mortality rates and so higher fish production.
Once habitat restoration work is completed in the Culter catchment we expect to see an additional 1,500 salmon returning to the Dee each year.
These salmon may be available to the catch and release rod fishery as far up river as Banchory, as our radio tracking studies show how fish may wander up to 20km upstream from where they eventually spawn.
Monitoring Fish Pass Success
A Vaki fish counter is installed at the top of the fish pass to record how many fish are using the pass to ascend the dam. The counter records the length of each fish. We assume that all fish longer than 50cm are salmon, fish between 30 and 50cm length are sea trout and fish less than 30cm are brown trout. In practice, there is some size overlap, particularly between small salmon and large sea trout. Our scale data show we would expect 6% error in these classifications.
Lessons learnt
Image gallery
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Catchment and subcatchment
Site
Project background
Cost for project phases
Reasons for river restoration
Measures
MonitoringHydromorphological quality elements
Biological quality elements
Physico-chemical quality elements
Any other monitoring, e.g. social, economic
Monitoring documents
Additional documents and videos
Additional links and references
Supplementary InformationEdit Supplementary Information
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