Disputed Foyle is biggest sea Lough

The report, produced by the Northern Ireland Environment Agency (NIEA) and the Agri-Food and Biosciences Institute (AFBI), points out that Lough Foyle is larger in area than Strangford - which the popular BBC ‘Coast’ series amongst others has labelled “the largest sea Lough in the British Isles.”

Not so, according to ‘Northern Ireland State of the Seas’ which covers 14 different aspects of marine environmental quality ranging from fish and foodwebs to marine litter and underwater noise.

The report points out how Lough Foyle - at 186 square kilometres - is the largest sea Lough in the British Isles. Strangford - at 159 square kilometres - comes a close second and is admittedly deeper and holds more water than the Foyle.

The report notes: “Seventy five percent of the land draining into it is in Northern Ireland. Lough Foyle is our largest true estuary.”

The survey also acknowledges Dublin’s die-hard insistence on a territorial claim on the Lough which is not accepted by London.

Whilst the Republic of Ireland’s territorial claim over Northern Ireland was dealt with by the amendment of articles 2 and 3 of its constitution in 1999 Dublin still covets Lough Foyle.

The Irish Governmnet lays claim to half of the waterway whilst the Foreign and Commonwealth Office (FCO) insists all of Lough Foyle is British and that is not negotiable at present.

‘NI State of the Seas” takes cognisance of this stating: “The UK and Republic of Ireland have never reached a clear agreement on jurisdiction within the cross-border areas of Lough Foyle and Carlingford Lough.

“However, these areas are often now managed as ‘shared waters’ between two neighbouring European Member States with two-way consultation.”

Elsewhere, the report explains how marine archaelogists have recenlty accelerated the search for dinosaurs and sunken treasure in Lough Foyle but that more work is needed.

Scelidosaur bones have previously been discovered on the Antrim coast and ‘NI State of the Seas’ says efforts towards further discoveries are ongoing.

“Although significant inroads have been made in mapping and understanding our maritime heritage, there are areas of the coastline and seabed that have yet to be fully explored and researched.

“The archaeology of Strangford Lough and Rathlin Island has been well documented and similar work has commenced on the north coast and Lough Foyle.

“However, the rest of the coast needs to be investigated with the same level of scrutiny and it is hoped that this will be undertaken in future,” the report states.

The study goes on to note the presence of a number of invasive alien species in Lough Foyle - notably Pacific oysters and cord-grass.

Pacific oysters are grown at a number of intertidal sites in Lough Foyle with production ranging between 200 and 400 tonnes annually.

It points out how feral populations of Pacific oysters are now breeding successfully here and that this may bring about a fundamental change to the ecosystem of the area.

Pacific oysters are also known to have spawned in Lough Foyle. Meanwhile, cord-grass is now abundant in the Lough having colonised sheltered coastal mudflats at a tidal level below the normal coastal salt marsh vegetation, producing dense swards.

“These swards can slow the movement of water and increase the rate of sediment deposition. This in turn raises the general level of the marsh blocking out other species and reducing the biodiversity of the marsh and mudflat.

“On intertidal mudflats it reduces the food available for wildfowl and wading birds, notably eel grass beds and invertebrates,” the report warns.

Looking at native fisheries and aquaculture the survey finds the Lough Foyle the best quality estuary in Northern Ireland.

An ecological quality measure used to classify estuarine fish communities under the Water Framework Directive scores the Foyle/Faughan as ‘high’, the Bann and Newry as ‘good’, while the remaining three systems (Roe, Lagan, and Connswater) are ‘moderate.’

It warns about the potential negative impact that climate change may have on returning adult salmon numbers in Lough Foyle and notes how the elimination of netting seaward of the Lough will hopefully help boost recovery.

“Recent reductions in netting were achieved through voluntary buy-out of licenses in the County Antrim area, the cessation of fishing for salmon seaward of Lough Foyle and a reduction in the numbers of remaining licenses within Lough Foyle,” it states.

Mussels and oysters

Natural shellfish populations are also covered including wild and blue mussels and native and pacific oysters.

The wild mussel fisheries in the Foyle “settle naturally” and contributed to reported landings in 2008 of around 1,000 tonnes.

It explains how native oyster stocks have historically been over-exploited in Lough Foyle due to a lack of regulation, which in part accounts for their boom and bust production.

The majority of the oysters captured in this fishery are landed to the Irish ports of Moville and Greencastle with a small amount landed in Northern Irish ports.

Apparently, bonamia ostreae, a parasitic disease of oysters, has been present in Lough Foyle since 2005 and has been reported in Strangford Lough, however there has been no evidence to date of any significant negative impacts. There are also blue mussels and Pacific oysters present in the Lough.

‘NI State of the Seas’ also discusses the hydrography of Lough Foyle telling us that land reclaim may affect sand banks at the estuary mouth.

“Land claim directly removes intertidal habitat. Significant areas of intertidal habitat have been lost in all of the sea loughs. Reclamation also reduces the tidal prism of coastal water bodies,” it notes.

“This means that less water flows in and out, tidal currents change and if there are sediment deposits at the estuary mouth they may change shape by erosion and accretion.

“This is most likely to happen in areas like Dundrum Bay and Lough Foyle which have mobile sand banks at their inlets,” it adds.

Despite acknowledging the pristine water quality at Benone - the best in Northern Ireland - it says that in 2006 the insecticide Lindane exceeded recommended values in Lough Foyle itself.

The World Health Organisation (WHO) class the substance as “moderately hazardous” and it has been shown to be toxic to the kidney and liver in toxicology tests carried out on rats.

The report is an attempt to chart the best way forward for Northern Ireland’s seas including Lough Foyle.

“The production of this Northern Ireland State of the Seas report is a key milestone in moving towards our vision of clean, healthy, safe, productive and biologically diverse oceans and seas.

“The report highlights areas of environmental improvements resulting from a sound understanding and a good evidence base. However, it also identifies areas where our knowledge is less complete,” it concludes.