Timing of instream works

River and Brook Lampreys spawn during the period March-April, while Sea Lamprey spawn during the period May-August. It is recommended that works in watercourses containing lamprey should only be carried out during the period August to September (except in the case of exceptional circumstances); however, river sections containing spawning habitat should be avoided completely during this period. Translocation and instream works including habitat creation should be undertaken outside of the lamprey spawning season; however, cognisance must be taken of the salmonid close season i.e. October-May inclusive.

Ennis Flood Scheme. The EIS for this scheme said there would be no instream works. This is clearly instream works and was undertaken during the lamprey spawning season in a SAC designated for lampreys.
Ennis Flood Scheme. The EIS for this scheme said there would be no instream works. This is clearly instream works and was undertaken during the lamprey spawning season in a SAC designated for lampreys.

River sections containing spawning habitat should therefore be avoided completely during the spring to late summer period. This is particular should apply to sea lamprey habitats, particularly those within River SACs. It is noted that restrictions to instream works should also apply to salmonid targeted ‘fisheries’ development works.

It is also noted that instream works include construction of river walls during the construction of urban flood alleviation schemes. Removal of weirs and barriers to migration to lampreys, despite bringing long-term benefits to lampreys, should only be undertaken outside the lamprey spawning season.

Click here to download the ECOFACT Survey & Mitigation Calendar.

The following posts are also relevant to the above:-

We are campaigning for (1) a formal close season for instream works on lamprey rivers (that is enforced), and (2) that all instream works in Ireland are assessed appropriately in terms of their impacts on lampreys.

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