Dáil Éireann Debate, Tuesday - 27 June 2023
110. Deputy Mairéad Farrell asked the Minister for the Environment, Climate and Communications the extent of the invasive roach population in Lough Corrib and Lough Mask, which are both SACs; the consequences for the native brown trout and Atlantic salmon populations; and if he will make a statement on the matter. [30605/23]
View answerI am advised by Inland Fisheries Ireland (IFI) that Roach is a "cyprinid", native to most of Europe and was introduced into Ireland some 130 years ago in the 1880’s. Since the 1950s it has become one of the most common fish species in Ireland, particularly in eutrophic lakes, canals and slow flowing parts of large rivers in the midlands and north midlands.
Roach as a non-native is subject to restrictions under Regulations 49 (prohibition on introduction and dispersal) and 50 (prohibition on dealing in and keeping) of the European Communities Birds and Natural Habitats Regulations, S.I. No. 477 of 2011, under the remit of the National Parks and Wildlife Service (NPWS).
Roach was first identified in Lough Corrib in the early 1980’s, observed in routine netting operations on the lake from the late 1980s until 1992 when a decline was observed. The most recent survey of the lake in 2021 indicate an apparent increase in abundance in the lower lake, but a decline in abundance in the upper lake since earlier surveys.
Roach was first recorded in Lough Mask in a fish stock survey in 1996. The most recent survey of the lake in 2022 indicated that roach were abundant in the lake.
The establishment of roach in waterbodies where they are not present may potentially result in competition with other species, such as trout, which occupy the same ecological niche.
Roach do not occupy the same ecological niche as salmon. Salmon juveniles reside in fast flowing rivers and adult salmon rarely feed in lakes while on route to spawning beds and IFI advise there is little evidence on overlap in feeding habitats to the same extent as lake dwelling trout.
IFI also advise that roach is often the main prey item for pike in many waters and may serve a useful purpose of alleviating predation pressure on trout and salmon.
Once introduced it is effectively impossible to eliminate roach from larger waterbodies. Preventing colonisation is the best management measure available. Roach can tolerate enriched waters, so thrive in waters when there is deteriorating water quality and increased eutrophication.
The numbers of roach can be controlled/reduced by improving water quality and reducing the amount of nutrients entering waterbodies as required by the EU Water Framework Directive (WFD). IFI will continue to monitor the ecological status of fish stocks in selected lake and river waterbodies to contribute the work of the Environmental Protection Agency (EPA), for the purposes the WFD and for broader conservation purposes.
