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Fish Stock Survey of Lough Rea, August 2022

Lough Rea is situated in the Kilcolgan catchment in Co. Galway (Plate 1.1, Figure 1.1). It is an abstraction lake, providing water to the nearby town of Loughrea (County Galway Guide, 2010). The lake is situated at an altitude of 85m a.s.l., has a surface area of 301ha, a mean depth of 3.9m, a maximum depth of 23m and is categorised as typology class 10 (as designated by the EPA for the Water Framework Directive), i.e., shallow (<4m), greater than 50ha and high alkalinity (>100mg/l CaCO3).

Lough Rea has been designated as both a Special Area of Conservation (SAC) and a Special Protected Area (SPA) (NPWS, 2013 and 2010). It is a hard water lake, a habitat listed on Annex I of the EU Habitats Directive. The underlying geology of the area is of carboniferous limestone. Plant species characteristic of calcareous waters and common to the lake include stonewort species, Chara curta and C. contraria. Internationally important numbers of over wintering shoveler birds have been recorded at the site, along with nationally important numbers of tufted duck (Aythya fuligul) and coot (Fulica atra). The presence of these birds has led to the site being designated as a Special Protection Area (SPA) (NPWS, 2010).

Lough Rea is surrounded by intensively farmed pastureland and consequently the main threat to the lake comes from agricultural run-off and possible nutrient input from the town of Loughrea.

Fishing on Lough Rea is managed by the Loughrea Anglers’ Association. There are good numbers of rudd (Scardinius erythrophthalmus) and perch (Perca fluviatilis), along with a stock of pike (Esox lucius) present in the lake. Brown trout (Salmo trutta) with an average weight of 1.5lbs (0.6kg) are also found in the lake (O’ Reilly, 2010).

Lough Rea is fed by springs and small streams on the south-eastern shore and has poor spawning areas for trout (NPWS, 2013). Brown trout spawning is limited to a single narrow inflowing stream and to the outflowing stream and there has been a history of coarse fish and pike management and brown trout stocking in the lake. In the early 1920’s brown trout from nearby Lough Atorick in Co. Clare were
stocked into the lake which had previously been populated with coarse fish and pike (Healy, 1953). Further stocks of brown trout were introduced from Lough Atorick in 1936 and 1939 and this practice continued until at least the 1950’s. These stocks were supplemented by fry hatched out locally from ova supplied from Lough Owel in Co. Westmeath and elsewhere (Healy, 1953). Lough Rea Anglers Association operate a small hatchery on the lake and female brown trout have been stripped almost annually since 1939. Fish are stocked into the lake at the unfed fry stage.

The lake has been surveyed on three occasions since 2010 (2010, 2016 and 2016) (Kelly et al., 2011, 2014 and 2017). Species captured include, brown trout, perch, rudd, perch, pike, eel (Anguilla anguila) three-spined stickleback (Gasterosteus aculeatus) and nine-spined stickleback (Pungitius pungitius). While the species mix has remained similar across all sampling occasions, the relative size of the individual species populations has fluctuated between surveys.

This report summarises the results of the 2022 fish stock survey carried out on the lake using Inland Fisheries Ireland’s fish in lakes monitoring protocol. The protocol is WFD compliant and provides insight into fish stock status in the lake.

Topics: Lake Surveys 2022 , |