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  Atlantic Herring in 6aS/7b, Industry Acoustic Survey Cruise Report

  O’Malley, M.; Smith, T.; Mullins, E. (Marine Institute, 2020)

  An acoustic survey of Atlantic herring Clupea harengus was conducted in ICES areas 6aS/7b in Dec 2019 using the research vessel RV Celtic Voyager and the fishing vessel MFV Ros Ard SO745. This survey is the fourth in a time series that is hoped will be developed into a long-term index of spawning/pre-spawning herring in 6aS/7b. The survey design is based on the predicted distribution of this winter spawning herring in this area. Poor weather negatively impacted the survey in 2019, resulting in fewer transect miles completed and fewer strata areas covered than planned. In total, approximately 600nmi of cruise track was completed using 96 transects. This resulted in a total area coverage of approximately 865 nmi², a significant reduction compared to recent years. Parallel transect spacing was set at 3.5nmi for the Donegal Bay strata. Tightly spaced zig-zag transects were used in a relatively small area in Lough Swilly. A Simrad ES-120 7CD (120 kHz) split-beam echosounder was used to collect acoustic raw data. The transducer was mounted on a towed body from the Celtic Voyager in Donegal Bay and was pole mounted from the Ros Ard in Lough Swilly. Very strong herring marks were evident in Lough Swilly in deepest part of the channel. The herring marks continued for many miles in the upper Swilly, an area where boats in the monitoring fishery had also concentrated effort. There were some herring marks in discreet areas around Drumanoo Head, Bruckless Bay and Inver Bay in the Donegal Bay Strata. Biological samples from the monitoring fishery of herring were used to augment the samples from the survey. Herring samples were taken from boats fishing in Lough Swilly and Inver Bay as close spatially and temporally as possible to the survey in these areas. Herring were dominated overall by 1- and 2-wr fish, (52% of the overall numbers) followed by relatively strong 3- and 5-wr cohorts. The total stock biomass (TSB) estimate of herring for the combined 6aS/7b area was 10,506 tonnes (Lough Swilly = 9,363 tonnes, Donegal Bay = 1,143 tonnes). This is considered to be a minimum estimate of herring in the 6aS/7b survey area at the time of the survey, and a significant decrease on the previous 3 years surveys. The reduction in the survey area completed as a consequence of the poor weather resulted in the survey not containing the stock in 2019. However, the overall CV estimate on biomass and abundance for the survey area completed is low (~0.13) in 2019. This is driven by the improved survey design in Lough Swilly, with reduced transect spacing and increased transect miles in this strata. The CV for the Donegal Bay strata is relatively high (0.51), this is mostly caused by the over-reliance on a few acoustic marks of herring in Bruckless and Inver Bays in particular and many transects with little or no herring marks. The survey in 2019 had to be altered due to weather, requiring a change in design and approach. However, the template of focusing on discreet areas was generally successful and may provide a template for future designs, particularly when reduced effort is necessary during poor weather or resource limits.
• Scientific Investigations, 1909

  Holt, E. W. L.; Hillas, A. B. E.; Department of Agriculture and Technical Instruction for Ireland (Dublin, The Stationery Office, 1909)

  I. Report of a survey of trawling grounds on the coasts of Counties Down, Louth, Meath and Dublin. Part I, Record of fishing operations, by E. W. L. Holt, Plates I and II * II. Summary of reports relative to Eel Fry, 1909-10, by A. B. E. Hillas, B.A.
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  EMFF Offshore Reef Survey, Sensitive Ecosystem Assessment and ROV Exploration of Reef - SeaRover 2019 Cruise Report

  O'Sullivan, D.; Healy, L.; Leahy, Y. (Marine Institute, 2019)

  This report presents preliminary findings of the 2019 offshore reef survey over the Porcupine Seabight and adjacent areas. The survey is the final leg of an extensive three year project, beginning in 2017, that was coordinated and led by Ireland’s Marine Institute and INFOMAR (Integrated Mapping for the Sustainable Development of Ireland’s Marine Resource) and funded by the European Maritime and Fisheries Fund (EMFF) Marine Biodiversity Scheme and the National Parks and Wildlife Service (NPWS).
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  Newport Research Facility, Annual Report No. 63, 2018

  Marine Institute (Marine Institute, 2019)
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  Celtic Sea Herring Acoustic Survey Cruise Report 2019, 09 - 29 October, 2019

  O'Donnell, C.; Mullins, E.; Lynch, D.; Lyons, K.; Connaughton, P.; Power, J. (Marine Institute, 2019)

  In the southwest of Ireland and the Celtic Sea (ICES Divisions VIIaS, g & j), herring are an important commercial species to the pelagic and polyvalent fleet. For a period in the 1970s and1980s, larval surveys were conducted for herring in this area. However, since 1989, acoustic surveys have been carried out, and currently are the only tuning indices available for this stock. In the Celtic Sea and VIIj, herring acoustic surveys have been carried out since 1989. Since 2004 the survey has been fixed in October and carried out onboard the RV Celtic Explorer. The geographical confines of the annual 21 day survey have been modified in recent years to include areas to the south of the main winter spawning grounds in an effort to identify the whereabouts of winter spawning fish before the annual inshore spawning migration. Spatial resolution of acoustic transects has been increased over the entire south coast survey area. The acoustic component of the survey has been further complemented since 2004 by detailed hydrographic, marine mammal and seabird surveys.

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