Taking account of the conservation status reporting for these species and the relatively poor understanding of the life cycle requirements and balances in place with regard to habitat ecology, there is an imperative to employ the ‘Precautionary Principle’ for any and all works potentially affecting Lamprey species, within and outside designated conservation sites.
Primary threats affecting lamprey species relate to habitat loss, both by direct removal or alteration of the depositing silt habitat required by juveniles (ammocoetes) of all three species and also through the prevention or impediment to passage for adult Sea and River lamprey migration to spawning grounds upstream. The loss or restriction of upriver penetration for anadromous lamprey has significant adverse implications for dispersal and resource use within any catchment. Similarly the movement of brook lamprey adults within the smaller tributaries of a catchment to reach spawning grounds can be impeded by culverts and shallow bridge floors or aprons which often contain vertical drops at the downstream side. At a national level growing awareness of lamprey conservation issues is already reducing the impact of instream works, with respect to a historical absence of any management for these species; however, there remains significant scope for an improvement in awareness of the requirements of these protected species.
Like all fish species, Lampreys and their habitats are vulnerable to water pollution. Water quality pressures in low-lying catchments gives rise to pressures on adults, juveniles and ova. Ammocoetes are relatively immobile in the substrate and tend to concentrate in areas that include many age classes making them most susceptible to pollution.
Direct persecution and commercial exploitation are identified as impacts affecting both Sea and River lamprey in the European context, where Sea lamprey have historically been utilised as a fishing bait and with an active fishery for River lamprey extant in Finland and Baltic states. However, there is no significant commercial exploitation of these species in Ireland or the UK. In Europe, the Sea lamprey is not controlled as a pest, as it is in the United States, where barriers to passage are installed on salmonid watercourses as a management tool to limit Sea lamprey entering freshwater systems on the eastern seaboard.
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It is of significant importance that all three species of Lamprey in Ireland are listed on Annex II of the EU Habitats Directive (1992); in addition to River Lamprey being listed on Annex V of the same Directive. Taking account of the conservation status reporting for these species and the relatively poor understanding of the lifecycle requirements and balances in place with regard to habitat ecology, there is an imperative to employ the ‘Precautionary Principle’ for any and all works potentially affecting Lamprey species, both within and outside designated conservation sites.