Project number: 2002-056
Project Status:
Budget expenditure: $495,861.35
Principal Investigator: Neil Gribble
Organisation: Department of Agriculture and Fisheries EcoScience Precinct
Project start/end date: 29 Jun 2002 - 14 Nov 2007


Need for trawl mapping
Information on where trawling does and does not occur is needed by fishery managers, industry, GBRMPA and others to inform debate and decision making for the trawl fishery. By June 2002, VMS will have recorded all Queensland trawl effort (except the Moreton Bay fishery) every hour for 18 months. These data can be used to map the distribution and intensity of trawling better than ever before. These maps are required by July 2003 for implementation of the Queensland Trawl Plan. Such maps are also needed to model the ecological effects of trawling, since untrawled areas may provide refuge for some vulnerable bycatch species. Such maps will also help assess the required 40% reduction in bycatch.

Need to develop stock assessment and management for ESD
The Trawl MAC have named stock assessment and Review Events as their top research priorities, and VMS research as a high priority. There is a need to improve abundance indices, currently based on CPUE from trawl shots defined as square CFISH grids (6’ by 6’ or 30’ by 30’). This is unrealistic and can lead to significant errors in stock assessment. There is also a need to investigate the way targeting and depletion of aggregations interact with economic factors to affect CPUE.

We can meet these needs using effort and density indices at fine spatial and temporal scales, by using the functionality of newly developed commercial software to develop our modelling systems. Matrices of stock abundance in space and time can be mapped (see attached map) or used in stock assessment models. A major area of research need with the OceanFARM software is user definition of trawl signature and catch distribution functions, which differ between sectors of the trawl fishery.

The functionality must be integrated into the overall management and assessment strategy for each fishing sector. There is potential to substantially improve the reliability of stock assessments.


1. Review applications and potential of VMS mapping and OceanFARM software, and related approaches.
2. Develop trawl track and trawl signature definitions for each fishery sector, to use with TerraVision software.
3. Map the spatial and temporal intensity of fishing effort in each trawl sector, and estimate the distribution and extent of trawled and untrawled areas.
4. Map resource density indices for each fishing sector.
5. Use these methods to recommend (and achieve implementation of) improved Trawl Fishery Review Events, and develop improved stock assessment approaches for scallops, eastern king prawns and tiger prawns.

Final report

ISBN: 978-0-7345-0379-4
Author: Neil Gribble

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