SP 4 - Freshwater / riparian assemblage
- Code
- SP 4
- Priority species or species assemblage
- Freshwater / riparian assemblage
- Description
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This includes the following fish species: River Lamprey, Brook Lamprey, Sea Lamprey and Atlantic Salmon, one mollusc: Depressed River Mussel, one crustacean: White-clawed Crayfish and three bird species: Little Ringed Plover, Dipper and Sand Martin. These species inhabit freshwater and riparian habitats within Herefordshire and measures will support the restoration of their populations.
- Wider environmental benefits
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Reducing climate change impact
- Assemblage measure 1
- Minimise recreational disturbance
- Assemblage measure 1 description
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Recreational activities have potential to disturb species, damage suitable habitats and spread invasive non-native species and pathogens such as crayfish plague. along watercourses. Increased engagement with the public and key riparian stakeholders will help to reduce disturbance levels and mitigate the effects. This measure should focus on White-clawed Crayfish, Little Ringed Plover, Dipper and Sand Martin.
- Assemblage measure 2
- Control Signal Crayfish populations for White-clawed Crayfish population recovery
- Assemblage measure 2 description
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Signal Crayfish pose a threat to the native, White-clawed Crayfish through direct predation, outcompeting for habitat as well as disease, crayfish plague. Signal Crayfish populations must be controlled to enable White-clawed Crayfish populations to recover.
- Assemblage measure 3
- Control Zebra Mussel and Asian Clam for Depressed River Mussels
- Assemblage measure 3 description
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Zebra Mussels and Asian Clams are molluscs which when established on slow flowing watercourses or open water can dominate. These species alter oxygen levels within the water, preventing native species from surviving or outcompeting the Depressed River Mussel for habitat and food sources. These invasive species must be identified swiftly if recorded within Herefordshire, to prevent negative impacts on the Depressed River Mussel. Biosecurity measures will also support this measure.
- Assemblage measure 4
- Consider translocation above river obstacles
- Assemblage measure 4 description
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Many of the watercourses across Herefordshire include river obstacles, such as weirs, waterfalls, sluices, dams, culverts, fords and flap gates which prevent fish passage throughout their life cycle. Translocation of the three lamprey species into locations upstream of river obstacles should be considered to support their migration out to sea as they become adults. Further guidance is available here.
- Assemblage measure 5
- Consider fish passage technologies
- Assemblage measure 5 description
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Fish passage technologies could be employed at several of the river obstacles to enable free movement of fish upstream and downstream. There are several types of fish pass that can be fitted to obstructions as they cannot be removed. Careful consideration of suitable fish passes, and appropriate designs and approvals will be required. Further information is available here.
- Assemblage measure 6
- Conserve habitat at channel margins
- Assemblage measure 6 description
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The three Lamprey species rely heavily on channel margin habitat for their juvenile life stage, existing as larvae in accumulation of fine sediments present on the edges of watercourses. Thees channel margins habitats are threatened by dredging and channel maintenance activities and therefore, mitigation to conserve these habitats is vital for these species.
- Assemblage measure 7
- Create gravel spawning grounds
- Assemblage measure 7 description
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Atlantic Salmon require shallow gravel areas in clean watercourses to spawn, release or deposit their eggs. The creation of these gravel beds will allow Salmon to excavate nests or ‘redds’ for spawning to take place. Gravels could also be restored by removing fine sediments that have accumulated on top of gravels or breaking up of compacted gravels. These spawning grounds can also benefit the three lamprey species which require similar spawning habitats.
- Links to additional information and guidance