Oughterard Anglers - Corrib Facts & Conservation

The Oughterard Anglers & Boatmen Association is situated on the shores of what is generally accepted as the greatest wild brown trout fishery in the world. Lough Corrib or Loch Coiribe i nGaeilge is the second largest freshwater lake in Ireland covering an area 176km2 or 17,600 ha, having a maximum length of 43.5km and a maximum width running from west to east of 16.1km. In spite of its sheer size the lake has an average depth of only 6.5m or 21’ with the deepest part of the lake at 51m or 167’ situated between the Glann Shore and Doorus. There is an old saying that says there is an island on the Corrib for every day of the year, however according to a recent hydrographic survey carried out by a local cartographer noted that the number of islands on the lake varies around 1,332 depending on water levels. The majority of the lake is situated in Co. Galway but the northeast corner lies within the boundaries of Co. Mayo.

Lough Corrib was designated a Ramsar site on June 16th, 1996. It has also been designated a Special Area of Conservation.

While native brown trout including Ferox trout are the dominant species in the lake, it also contains the following fish (IFI Surveys 1996 & 2012).

  • Native Atlantic Salmon

  • Invasive Pike

  • Invasive Perch

  • Invasive Roach

  • Invasive Rudd

  • Invasive Bream

  • Invasive Roach/Bream Hybrid

  • Invasive Rudd/Bream Hybrid

  • Native Lamprey

Native eels also inhabit Lough Corrib but have not been documented in recent IFI surveys. Regrettably, it seems that native charr have become extinct in Lough Corrib with no fish surveyed since the 1980s.

The Corrib and its whole catchment area of Mask, Carra etc (3,101km2) drains in to the sea at the Claddagh through the Galway River commonly called the “River Corrib”. This is a short river of only 7.7km, but has a mean annual flow rate of 94.3m3 sec-1 making it the second biggest river in Ireland in terms of flow.

The Corrib catchment, with the exception of some western tributaries of Lough Corrib, was subjected to major drainage schemes during the mid 1800s, the 1950s and the 1980s. These schemes had major impacts on the hydrology and fisheries of the catchment and resulted in the reduction in size of Loughs Corrib/Mask and the loss of other lakes in the catchment. The impact of these schemes remains apparent today. The Galway River itself has been subjected to major engineering works since the middle ages when the Franciscan monks dug a channel to shorten the river (Friar’s cut).

During the Drainage and Navigation Scheme (1848-1858) of Loughs Corrib, Mask, and Carra the Galway river was deepened and a regulating weir was built to control water levels in the lake. During the 1950s further drainage works were undertaken in the catchment as part of the Corrib-Clare Arterial Drainage Scheme. Works associated with this project involved more extensive blasting and dredging of the Galway River and the replacement of the Galway regulating weir with the structure that exists today. In an attempt to mitigate the impact of the drainage schemes, a salmon hatchery was set up in Cong during the 1970s and during the 1990s, an EU funded physical rehabilitation programme or fisheries was undertaken in some areas of the catchment.

The Environmental Protection Agency (EPA), and its predecessors (An Fóras Forbatha, Environmental Research Unit), has assessed water quality (chemical & biological) in the Corrib catchment since 1985 as part of the National Water Quality Monitoring Programme. Overall, water quality in the Corrib catchment is just above the national average with 73.3% of river channel classified as being satisfactory (national average is 69.2%). During their 2001-2003 survey of Irish lakes the EPA rated Lough Corrib as being *’Mesotrophic’ but noted increased phytoplankton growth in the upper basin during this period (Toner et al, 2005).

*Mesotrophic lakes are water bodies with an intermediate level of productivity. These lakes are commonly clear water lakes and ponds with beds of submerged aquatic plants and medium levels of nutrients.

Oughterard village is situated on the Owenriff River which drains a region of approximately 68 Km2 and which enters the lake close to the ‘Boat House’ in the village. The river is a major migratory route for spawning Atlantic salmon and indigenous lake trout.

In March 2010, the EPA made the following statement on the Owenriff River system in their Corrib Water Management Unit Action Plan, which would be greatest interest to club members and visiting anglers to Oughterard.

The Owenriff river catchment includes a significant portion of the Connemara Bog Complex SAC/NHA in its upper catchment and the Lough Corrib SAC in the lower main river channel. The Lough Corrib cSAC in the Owenriff River has been designated for the Freshwater Pearl Mussel (FPM) species protected under Annex II of the EU Habitats Directive. This species is particularly sensitive to silt, turbidity and nutrient enrichment. Filamentous algae are also causing ongoing problems particularly in the Oughterard stretch of the river. The river has seen a decline in the FPM population since 2004 and a specific Sub-basin Freshwater Pearl Mussel Plan for this river catchment has been prepared to protect the FPM species. The most recent EPA biological assessment of the river indicates the following:

The Derrygauna River which flows into Loughaphreagaun in the upper catchment is classed at Moderate status due to the unfavourable conservation status of the FPM population located there. The Glashanasmearany river flowing between Loughaphreagaun and Lough Bofin has been classed as High status. The main Owenriff channel between Lough Bofin and Lough Adrehid, between Adrehid and Agraffard and down to Oughterard has been classed as Moderate again due to the unfavourable conservation status of the FPM. Biological sampling of other indicative species indicates that the Owenriff is generally good with good fish stock but the overriding factor in determining its status is the conservation status of the FPM. The upper reaches of the Glengawbeg, draining Lettercraffroe Lough is classed as High status as are the smaller tributaries flowing from Shannaghree Lough and through Rusheeny townland. The Bunowen, another tributary of the Owenriff was classed as Moderate.”

Chronological Order of Club Conservation Activities

  • 1852 to present - Oughterard Hatchery

Built in 1852, and run voluntarily by members of the Oughterard club and other clubs within the Federation of Lough Corrib Anglers. Inland Fisheries Ireland (IFI), annually licenses the oldest trout hatchery in the world. Migratory trout that are ready to spawn in the Owenriff system are netted annually every October. Ova and milt are removed from hen and cock fish respectively, with the spent fish being released unharmed back in to the lake. Up to half a million eggs are fertilised then incubated for five months, with the eggs being cared for on a daily basis by volunteers. The eggs grow naturally with out the risk of predation and on becoming fingerling-sized, most are spread around Lough Corrib to maintain a healthy trout population.

  • 1995 - O’Sullivan Water Quality Survey

In 1995 the largest independently undertaken water quality evaluation of any Irish lake was commissioned by Lough Corrib Angling Federation, with a major input from members of the Oughterard Angling Club. Dr. Roderick OSullivan assessed 31 Corrib sites for eleven chemical parameters over a four-month period and his findings were published in 1996. The objectives were to develop a comprehensive profile of the water quality throughout the Upper and Lower Lough Corrib utilising as many sites and parameters as possible.

The following were some of the studies findings:

  1. Phosphorus concentrations were found to be to high in many sites

  2. Algal blooms, due to poorly treated sewage, had contaminated western shores

  3. The mouths of most tributaries were silted and overgrown

  4. Evidence of eutrophication was widespread on the Lower lake

  5. The B.O.D. and Dissolved Oxygen values of many sites failed to comply with E.U. Salmonid Water Regulations

  • 2000 - Carra/Mask/Corrib Water Protection Group (CMCWPG)

Set up in 2000 by a group of anglers who were concerned about the poor water quality on Loughs Carra, Mask and Corrib. The Oughterard Angling Club helped fund the group’s office in Headford, Co. Galway and has representation on their governing body.

CMCWPG deal with a large variety of water quality issues affecting, or likely to affect the water quality of the catchment. The Group in conjunction with the angling clubs and federations keep a watching brief on developments and licenses that have potential to impact water quality.

The group pays close attention to all emerging environmental legislation be it EU or National. The Group monitors the implementation of this legislation by the local authorities and will lobby and provide feedback where appropriate. The group participates in and puts forward submissions to the National Environmental NGOs under its umbrella Group SWAN (Sustainable Water Networks) focusing mainly on the Water Framework Directive.

Between October 2004 and June 2005, the group, in conjunction with the Oughterard Angling Club, held 3 public meetings of the issues of pollution in the Lough Corrib catchment. The majority view was that the increase in nutrients levels, in particular of phosphate, in the local rivers/streams was a result of felling practices in the forestry plantations. As a result, a government moratorium was put on felling in the Owenriff Catchment area.


  • 2004 - Moorhens’ Owenriff River Pearl Mussel Study

Pearl mussel (Margaritifera margaritifera and Margaritifera durrovensis) are ancient creatures, there are fossils of this family dating back to the dinosaurs 150 million years ago. When the female releases the tiny larvae (called glochidia) they swim up and attach to the gills of nearby trout and salmon, this does not harm the fish. After a few months, the young mussels, still only half a millimetre in length, drop off the fish and bury themselves in the river bed gravel until old enough to withstand the flowing water above.

In 2004 Dr. Evelyn Moorkens, renowned expert on the freshwater pearl mussel conducted a study on the Owenriff River of what is the oldest living creature in Ireland, they can live up to 130 years of age. Her findings showed that due to phosphate run-off from forestry felling on the Owenriff catchment, there was an alarming mortality rate amongst juvenile mussel.

Members of the Oughterard Angling Club helped to facilitate this study, and arranged for Dr. Moorkens to address the people of the town in October, 2004, in what was the first of 3 public meetings on the issue of pollution in the Owenriff River and Lough Corrib.

This pearl mussel is protected under the Bern Convention, the Irish 1976 Wildlife Act and the EU Habitats Directive and is now endangered due to the poor quality of Irish rivers.

  • 2009 - Oughterard club highlights illegal and criminal introduction of invasive pike to the Owenriff system

In 2009, concerned club members informed Inland Fisheries Ireland (IFI) of the illegal introduction of predatory invasive pike to Loughs Bofin and Agraffard. This introduction was a mindless act of environmental vandalism as the Owenriff system is a Special Area of Conservation (SAC) and the most important spawning/nursery catchments for trout and salmon (salmonids) in the whole Corrib system.

Unfortunately these lakes now have significant and rapidly expanding invasive pike population, which only have juvenile trout/salmon to feed on. Pike in this river system are an invasive predatory species, which will have a major impact on stocks of trout and salmon, formerly the dominant species in these lakes. As of late 2017, the Owenriff system is mostly devoid of its native trout. Invasive pike are found in Lough Corrib itself and have only existed in the lake for roughly 200 years. However, the Canrawer waterfall prevented invasive predatory pike from establishing themselves in the Owenriff system. In other words, it was a natural barrier to their migration.