Brook lamprey spawning season

The photos below show brook lampreys Lampetra planeri nest building and spawning in a tributary of Lough Derg, Co Tipperary. These photos were taken on the afternoon of the 1st April 2014. This is the first brook lamprey spawning activity that we observed this year.

Unlike the two other Irish lampreys species, adults brook lampreys are non-parasitic and do not migrate to the sea. Adult brook lamprey spawn in gravel close to the soft sediment in which they were previously resident. Brook lampreys are communal spawners and they die soon after spawning. After hatching the larvae leave the nest and distribute themselves by drifting downstream and burrowing in suitable areas of silty sand.  The young lampreys are blind filter feeders, feeding on detritus and other organic matter for up to six years (in Ireland and the UK) before maturing.

Brook lamprey is the most common of the three species of lamprey that occur in Ireland; however they are increasing threatened by river engineering works, such as drainage works and drainage maintenance works, and water pollution. Even minor barriers in rivers (i.e. bridge underpinning) can prevent their migrations.  Despite being listed on Annex II of the EU Habitats Directive and Appendix III of the Bern Convention, in reality they have effectively no protection in Ireland. If we we do not do something about this they may well become as rare here as they have become in other areas of Europe.

For more on the Brook lamprey please see this page.

ECOFACT are Ireland’s leading lamprey experts and if you have any queries about lampreys please do not hesitate to contact us.

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