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:TCDX. Monteys: GSI

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Project Overview

BIM-Main project 2002-2004 – (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

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Scallop Project –Main Elements

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)

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Background to Mapping Programme

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

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Mapping program main elements

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

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To date:

MBES coverage-Bathy/BS complex heterogenous seabed characterised by small sand and gravel

waves and elongate well organised dune-like bedforms Two dominant acoustic facies sediment types clearly visible Concept proved: confirmed sharp correlation between bs and

stock density Other aspects are far advanced e.g:

Final processing/analysis Towed video GT completedBathymetric tidal reduction GIS Visualisation-IntegrationGranulometry completed Dissemination

Sled mounted U/W video camera was towed across seabed to collect continuous imagery throughout 1km 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

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Conclusions

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 rugosity-

complex 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

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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

•BlueGlen-Tim McCarthy

•CMRC-Volunteers!