The Weir, Sion Mills, River Mourne 10 Feb 2024 DSC_1124-2
The River Mourne once had the reputation of being one of the best atlantic salmon rivers in Europe alas this is now not the case. With depleating north atlantic salmon stocks on the Foyle system incliding the following countries: Canada, Denmark, England, Finland, France, Greenland, Germany, Ireland, Northern Ireland, Norway, Portugal, Russian Federation, Scotland, Spain, Sweden, USA, Wales the number of returning salmon to our rivers to spawn has declined by a stagering 70% in the last 25 years. The salmon population in Great Britain and Ireland is now endangered.
Between 1983 and 2016, a period of just 33 years, numbers of wild Atlantic salmon prior to any fishing taking place (known as the pre-fishery abundance, or PFA) fell by more than half. The rate of decline was most dramatic from 1983 to 1990, when salmon numbers fell from around seven million to five million fish. And while the rate of decline since 1990 has slowed, a further 33% of salmon have been lost, meaning the number in 2016 was estimated to be around 3.38 million.
Prior to the 1960s, countries made their own rules about salmon harvest while there was no international discussion. The North Atlantic Salmon Conservation Organization (NASCO) was established in 1984 after the Convention for the Conservation of Salmon in the North Atlantic Ocean. This convention created a large protected zone free of targeted fishing for Atlantic salmon in most areas beyond 12 nautical miles from the coasts. This resulted in an immediate reduction in the commercial salmon fishing which, at its peak in 1973, harvested some 3.5 million salmon.
Climate change impacts both the marine and freshwater phases of the Atlantic salmon’s life cycle through changes in water temperature, habitat quality and survival at sea. Additionally, increasing freshwater temperatures affect how far south salmon populations can exist.
Water pollution is a major cause of the decline in stocks of Atlantic salmon, with all life stages of fish affected both directly through exposure to chemicals and acidified waters and indirectly through runoff causing eutrophication of aquatic habitats in both fresh water and the ocean.
Aquaculture impacts Atlantic salmon stocks through the genetic effects of farmed salmon escaping into wild populations, and mortality from sea lice and diseases spreading to the wild salmon stocks. Containment of farm salmon stocks, proper siting of fams away from esturies and sea-lice control are important considerations for aquaculture operations.
Over-exploitation occurs when too many fish are removed from a population in freshwater or marine environments, leading to that population falling below a sustainable level. Ultimately, this results in fewer returning adult females laying fewer eggs and a far less resilient population.
The weir in Sion Mills during high flow is 162m wide and is covered by 2 x channels, channel No. 1 is 5m wide and channel No. 2 is 1m wide. Therefore, 156m of the river is uncovered, so fish can pass uncounted. The counter was installed in May 1997 with the first data being collated in June 1997. The expected management target for fish upstream is 8,000, this year as of 31st December 2023 only 448 fish have been counted which is about 5.6% of the management target. On the other hand, the river Finn fish counter which is located at Killygordon covers the complete width of the river 27m has a management target of 5,410 and the current fish count up to 31st December 2023 is 1750 salmon which is about 32% of the management target. This provides an indication of the problem.
The Weir, Sion Mills, River Mourne 10 Feb 2024 DSC_1124-2
The River Mourne once had the reputation of being one of the best atlantic salmon rivers in Europe alas this is now not the case. With depleating north atlantic salmon stocks on the Foyle system incliding the following countries: Canada, Denmark, England, Finland, France, Greenland, Germany, Ireland, Northern Ireland, Norway, Portugal, Russian Federation, Scotland, Spain, Sweden, USA, Wales the number of returning salmon to our rivers to spawn has declined by a stagering 70% in the last 25 years. The salmon population in Great Britain and Ireland is now endangered.
Between 1983 and 2016, a period of just 33 years, numbers of wild Atlantic salmon prior to any fishing taking place (known as the pre-fishery abundance, or PFA) fell by more than half. The rate of decline was most dramatic from 1983 to 1990, when salmon numbers fell from around seven million to five million fish. And while the rate of decline since 1990 has slowed, a further 33% of salmon have been lost, meaning the number in 2016 was estimated to be around 3.38 million.
Prior to the 1960s, countries made their own rules about salmon harvest while there was no international discussion. The North Atlantic Salmon Conservation Organization (NASCO) was established in 1984 after the Convention for the Conservation of Salmon in the North Atlantic Ocean. This convention created a large protected zone free of targeted fishing for Atlantic salmon in most areas beyond 12 nautical miles from the coasts. This resulted in an immediate reduction in the commercial salmon fishing which, at its peak in 1973, harvested some 3.5 million salmon.
Climate change impacts both the marine and freshwater phases of the Atlantic salmon’s life cycle through changes in water temperature, habitat quality and survival at sea. Additionally, increasing freshwater temperatures affect how far south salmon populations can exist.
Water pollution is a major cause of the decline in stocks of Atlantic salmon, with all life stages of fish affected both directly through exposure to chemicals and acidified waters and indirectly through runoff causing eutrophication of aquatic habitats in both fresh water and the ocean.
Aquaculture impacts Atlantic salmon stocks through the genetic effects of farmed salmon escaping into wild populations, and mortality from sea lice and diseases spreading to the wild salmon stocks. Containment of farm salmon stocks, proper siting of fams away from esturies and sea-lice control are important considerations for aquaculture operations.
Over-exploitation occurs when too many fish are removed from a population in freshwater or marine environments, leading to that population falling below a sustainable level. Ultimately, this results in fewer returning adult females laying fewer eggs and a far less resilient population.
The weir in Sion Mills during high flow is 162m wide and is covered by 2 x channels, channel No. 1 is 5m wide and channel No. 2 is 1m wide. Therefore, 156m of the river is uncovered, so fish can pass uncounted. The counter was installed in May 1997 with the first data being collated in June 1997. The expected management target for fish upstream is 8,000, this year as of 31st December 2023 only 448 fish have been counted which is about 5.6% of the management target. On the other hand, the river Finn fish counter which is located at Killygordon covers the complete width of the river 27m has a management target of 5,410 and the current fish count up to 31st December 2023 is 1750 salmon which is about 32% of the management target. This provides an indication of the problem.