Date: 29 September 2003
A study commissioned by the Marine Institute into the condition of seabed sediments in Inver Bay, McSwynes Bay and at the Killybegs Harbour dredge spoil site, indicates that the dredge spoil from Killybegs Harbour did not cause the salmon mortalities at Inver Bay and McSwynes Bay in July/August 2003. This finding is consistent with the results of monitoring and analysis of the dredge spoil operation carried out by the Department of Communications Marine & Natural Resources. The study also indicates little evidence of recent trawling activity in Inver Bay.
The Sediment Profile Imagery (SPI) survey by Aqua-Fact International Services Ltd. in August 2003, was issued today to local producers in Inver Bay and McSwynes Bay.
The Marine Institute, the marine research and development agency leading the investigation, has met on several occasions with both the Department of Communications, Marine & Natural Resources (DCMNR) in Dublin and with the salmon producers in Donegal to inform them on the status of the investigation. The SPI report is the third interim report issued by the Marine Institute to local aquaculture operators and the DCMNR.
The Marine Institute was mandated by the Minister in July to undertake detailed investigations when it became apparent that significant mortalities had occurred in Salmon Farms in Donegal Bay. Mr. Micheal O'Cinneide, who is leading the Marine Institute investigation said, "The Marine Institute has committed significant time and dedicated key staff members to this investigation including fish health experts, chemists and environmental scientists. We have also commissioned studies by veterinary practitioners, and sought advice from international experts in salmon farm mortalities associated with gill damage."
The investigation has shown that the farmed salmon stocks in Inver Bay and McSwynes Bay suffered significant damage to the gills, causing the fish to suffocate. A number of potential causes have been investigated and eliminated, however a definitive cause has not yet been established.
The investigation is ongoing and encompasses a wide variety of aspects including fish health, chemistry, seabed conditions, phytoplankton and oceanography, fishing activity, and fish-farm operations.
"The scope of the investigation has extended as potential causes are eliminated, and therefore it has taken longer than initially anticipated," said Mr. O'Cinneide. The scope of the study was extended nation-wide in mid-September, at the request of the Minister, in the light of information pointing to elevated mortality levels over recent months in salmon farms along the western seaboard.
Ends.
NOTES TO THE EDITOR:
Summary of Aqua-Fact SPI Study Findings
Survey of Seabed Sediments in Inver Bay, McSwynes Bay and Killybegs Harbour dredge spoil disposal site.
As part of its investigation into the mortalities of farmed salmon in Inver Bay and McSwynes Bay, the Marine Institute commissioned a survey of seabed conditions in the affected bays, as well as in the area used for the disposal, in 2002, of dredge spoil from Killybegs Harbour.
The survey, carried out by Aqua-Fact International Services Ltd. used Sediment Profile Imagery (SPI), which takes in situ photographs of vertical sections of the seabed sediments. This can provide information on the physical, chemical and biological status of the seabed, and can determine the quality or "health status" of the seabed. It can also show any recent disturbance or changes in seabed conditions. Photographs of the sediment surface were also taken.
A total of 131 stations were sampled in the survey area last month, comprising 90 in Inver Bay, 10 in McSwynes Bay and 31 in the vicinity of the spoil site.
Inver Bay
The majority of stations in Inver Bay showed a predominance of fine to very-fine sands in the topmost layer of sediments with patches of coarser sediments on the west side of the bay. These results correspond well with those found in a previous survey of the area carried out in 1997. Healthy living maerl, indicative of good water quality, was also observed at a number of stations.
Outside of the immediate influence of fish cages, sediments were shown to be healthy and aerated. In the vicinity of fish cages the environment showed varying degrees of habitat disturbance that can be attributed to organic enrichment and is an allowable impact of such activity.
Only three of the 90 stations sampled during the survey showed any evidence of recent physical disturbance. No direct evidence of extensive trawling activity was detectable in the SPI images or seabed surface photographs. Deposit feeding species were imaged actively feeding on the sediments providing further evidence that there has been little seabed disturbance in the recent past.
McSwynes Bay
All stations sampled in McSwynes Bay showed a mature healthy habitat and biological community status, with healthy aerated sediments.
There is no evidence from the survey to suggest any recent physical disturbance or deposition of sediments in McSwynes Bay.
Killybegs Harbour Dredge Spoil Disposal Site.
As part of the Killybegs Harbour development programme approximately 110,000m3 of harbour sediments were disposed of at sea. The disposal operation ended in early August 2002.
The majority of stations on, and in the vicinity of, the dredge spoil disposal site were shown to have a predominance of fine to medium sands in the topmost layer of sediments. Patches of coarse sand were also recorded. Some physical disturbance was evident at two of the stations situated to the northwest of the disposal site but the level and extent of the disturbance appeared quite limited.
The results of the survey indicate significant deposition of material at the site with the presence of loose fine sediments. The pattern of results fits a typical dredge spoil disposal site dispersion pattern. This is supported by the results of bathymetric surveys carried out before and after the disposal operation, which showed a decrease in depth of up to 30cm after spoil disposal.
The results indicate that deposited material has been reworked into the sediment through feeding and burrowing activities of resident sediment dwelling organisms. Significant recolonisation and reworking of the sediments at the centre of the site is also apparent. The bathymetric data, together with the SPI data from this study, indicate that the most significant deposits of dredge spoil were found within a radius of approximately 500m from the centre of the disposal site.
In summary, the results of the survey indicate little evidence of recent physical seabed disturbance in Inver Bay, in McSwynes Bay or at the dredge spoil disposal site.
Additional reports related to the disposal of dredge spoil from Killybegs Harbour
In addition to Aqua-Fact's SPI study, the Marine Institute considered information available in other reports related to the disposal of dredge spoil from Killybegs harbour as well as information previously provided in Interim Reports as part of the ongoing investigation into fish mortalities at Inver Bay and McSwynes Bay in July/August 2003.
1. Aquatic Services Unit, Cork, (2001) Baseline Survey of a proposed dredge spoil dump site, Killybegs, Co. Donegal
2. Kirk, McClure Morton (2001) Killybegs Fishery Harbour Development. Dredger Operation Model
3. Kirk McClure Morton (2001) Killybegs Fishery Harbour Development. Dredge Spoil Disposal Modelling, Donegal Bay
4. Kirk McClure Morton (2001) Killybegs Fishery Harbour Development. Dredge Spoil Disposal Modelling, Donegal Bay (Addendum Report)
5. Wood Environmental Management Ltd. (2002) Benthic Monitoring of the dredge spoil disposal site, Donegal Bay - Sampling Programme 1
6. Wood Environmental Management Ltd. (2002) Benthic Monitoring of the dredge spoil disposal site, Donegal Bay - Sampling Programme 2
7. Kirk McClure Morton (2003) Killybegs Fishery Harbour Development Silt Dredging and Disposal Operations, Monitoring Results (May 2002 -July 2003).
8. Kirk McClure Morton (2003) Killybegs Harbour Development Environmental Impact Assessment Statement
9. Application to the Marine Licence Vetting Committee for a Dumping at Sea License for Dredge Spoil from Killybegs Harbour (2001)
10. Salmon Mortalities at Inver Bay Finfish Farms - First Interim Report by Marine Institute to the Department of Communications, Marine & Natural Resources, 23rd July 2003
11. Salmon Mortalities at Inver Bay Finfish Farms - Second Interim Report by the Marine Institute to the Department of Communicaitons, Marine & Natural Resources, 11th August 2003.
About the Marine Institute
The Marine Institute is the national marine research & development agency. The Institute provides objective scientific advice to Government on marine environment and industry, and provides management advice and Research and Development support to industry as an agent for the Department of Communications Marine & Natural Resources.
The Marine Institute runs the national aquaculture monitoring programme which is one of the most comprehensive in the world.
About the Department of Communications, Marine & Natural Resources
The Department of Communications Marine and Natural Resources is the licensing authority and regulator for the aquaculture industry.
Records relating to the Department's monitoring of the Killybegs Harbour dredge spoil site are available for inspection at the Department's Project Site Office in Killybegs
About Aqua-Fact International Services Ltd
Aqua-Fact is an Environmental Consultancy specialising in monitoring and managing resources in marine, freshwater and terrestrial environments. Services include environmental, hydrographic, engineering, photographic and filming capabilities incorporating specialised sampling techniques. Aqua-Fact was has ISO 9002 quality certification which ensures confidence in the procedures and practices applied in support of all services provided by Aqua-Fact personnel.
For more information please contact:
Lisa Fitzpatrick
Communications Officer Marine Institute Galway Technology Park Parkmore
GalwayTel: 091 730 400
Mobile: 087 293 7476
Email: lisa.fitzpatrick@marine.ie