Multibeam Sonar Mapping and Scallop Stock Assessment GIS

Multibeam Sonar Mapping and Scallop Stock Assessment: GIS Data Integration in Support of Sustainable Fisheries Management Gerry Sutton O. Tully, J. Hickey: BIM A. Hervas: TCD X. Monteys: GSI

Project Overview l BIM-Main project 2002 -2004 – l (MBES surveying commenced in 2001) Main objectives: – – – To provide key info for fisheries development and management Stock levels assessment Physical and environmental controls on recruitment HYDRO-04

Scallop Project –Main Elements l l l Application of biological stock assessment models-sampling program (TCD/Kilmore Coop) Sedimentary characterisation and ID beds (CMRC) Fine resolution hydrodynamic model-tidal/larval circulation (MARCON) HYDRO-04

Background to Mapping Programme l l Early US/Canadian programs based on water depth or commercial effort- crude sediment maps only Scallop preference for sand/gravel MBES surveys revealed sediment heterogeneity The work of Kostylev et al (2001) suggested: – – strong influence of sediment type on scallop distribution scallop abundance and fishing success can be predicted from multibeam backscatter data HYDRO-04

Mapping program main elements l l High resolution mapping of seabed morphology and sedimentary facies in scallop grounds Determine and refine bs/stock density correlation Determine high abundance areas within known grounds Apply results in new areas HYDRO-04

To date: l MBES coverage-Bathy/BS l complex heterogenous seabed characterised by small sand gravel waves and elongate well organised dune-like bedforms l Two dominant acoustic facies sediment types clearly visible Concept proved: confirmed sharp correlation between bs and stock density l Other aspects are far advanced e. g: l Final processing/analysis Towed video GT completed Bathymetric tidal reduction GIS Visualisation-Integration Granulometry completed Dissemination HYDRO-04

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Sled mounted U/W video camera was towed across seabed to collect continuous imagery throughout 1 km transects within a representative selection of sediment facies throughout study area. Video signals were encoded with DGPS allowing video image position to be accurately overlain and correlated with seabed facies maps HYDRO-04

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Conclusions l l l l l EM 1002 data is more than adequate for bathy and habitat/biotope mapping-NB operator settings critical for BS not just sounding Near offshore Ireland tidal model needs to be resolved Strong MBES BS/Scallop relationship exists for this stock/area MBES BS predictive for fishing success High degree of heterogeneity in sediments both PS and rugositycomplex range of bedforms even in uniform area Sediment samples relatively poor GT alone High resolution video v. useful/required for GT Powerfull integration/visualisation tools required Seabed classification technology has arrived but NBB GT/Slopes/Operator Settings HYDRO-04

Acknowledgments • BIM-NDP • Kilmore Fishermans Co-op-skippers/crews • Marine Institute-All vessel ops team and crews, • MI-Fisheries-Colm Lordan-UW video • GSI-NSS team • Blue. Glen-Tim Mc. Carthy • CMRC-Volunteers! HYDRO-04

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