This revised proposal focuses our original whole of ecosystem approach for blue grenadier biomass and its variability to be targeted on the development of the acoustic methodology. This refocusing has necessarily required the reduction of data collection and analysis in the environmental area. It is the considered view of the proponents (CSIRO Marine and Industry partners) that the environment variables should be explored in a more exploratory fashion within this proposal at a reduced cost. Specifically we address the refocusing and the need to explain how data collection and biomass estimation may evolve over the long term.

This project proposes to develop a cost-effective acoustic observation system that covers the primary canyon spawning locations in each of three years, and which can be implemented as an ongoing method (Kloser et al, 2001; report 99/111). In the development phase it will be necessary to carry out critical research to develop the acoustic methods to move from relative to absolute measures by understanding dominant species target strengths and identification of species. Outside the dominant canyon regions the ability to accurately identify blue grenadier is difficult due to lower density and association with other fishes of similar reflectance. Our ability to estimate biomass in this regions will be limited by species identification issues. Environment variability interpreted from acoustic recordings within and between seasons will be developed to provide ecosystem based information associated with biological, physical and oceanographic data. This research should assist to develop an understanding of the relationship between Blue Grenadier stock size their dynamics and the environmental variability leading to better management advise and MSC certification.

In the first year we plan to carry out an extensive survey using industry vessels to obtain a biomass estimate of the spawning blue grenadier. Industry vessel based acoustic surveys when planned and designed to minimise sampling error and biases should provide an index of abundance. These industry observations will be converted to an absolute assessment based on the fishes target strength, species composition and an estimate of fish turn-over on the spawning grounds. Critical research will be undertaken in this project to estimate target strength and species recognition of dominant species groups and reduce uncertainties identified in the acoustic method using information gained from a national facility research voyage in the second year. The target strength of the dominate fishes will be estimated by modelling the dominant fish species acoustic target strength as well as in-situ target strength and species composition measurements using a deep towed multi-frequency acoustic system and a targeted depth stratified biological net capture systems for identification. To model the acoustic scattering of blue grenadier it will be necessary to characterise the reflective components in the body of swimbladder, flesh, bone and lipids. This will be achieved by dissection, CAT scans and lipid extraction. Estimations of swimbladder size will be supplemented with measurements of fish buoyancy required at depth using a specialised pressure chamber. These measurements will enable a detailed scattering model to be developed and associated with in situ target strengths provide a conversion of the acoustic data to an absolute estimate of spawning biomass.

The industry and research vessel data collected at the canyon sites and on the upper slope need to be related to the larger-scale environment driving interannual variability. The high recruitment variability in this fishery is probably due to environmental factors and methods that can predict or indicate factors associated to recuitment variability are worth exploring. An earlier version of this proposal included developing low cost methods of measuring physical oceanographic, biological and biochemical metrics and comparing these to historical trends. The FRDC board and one reviewer were not supportive of this part of the proposal at this time. CSIRO Marine and Industry partners still consider that development of a balanced understanding of the biomass and the environment is worthwhile. During the project we will identify other environmental data that can be measured on an ongoing basis at low cost. In this proposal the field data collected will be related to available oceanographic information and form the basis of developing hypotheses on environmental connections. A separate proposal will follow to explore a more ecosystem based approach to the Blue Grenadier fishery management.

To advance low-cost, industry-based remote acoustic sensing methods in a strategic way requires scientific input. Once methodologies have been established and limitations identified, the stock assessment process can rely on industry acoustic data and the associated (optimized) physical and biological ground-truthing. Importantly, implementing industry-based observation systems will more formally integrate industry knowledge of fishery dynamics and variability within and between seasons into the stock assessment process. The ability to develop more integrated stakeholder based monitoring systems will provide greater ownership of the management process. In particular, the utility of industry acoustic data to provide a low-cost index of abundance for blue grenadier is an exciting prospect.

The success of this project will be determined by adoption of these results by management and industry and MSC certification. To ensure appropriate uptake of the research requires a close relationship between research providers and industry partners. To begin this relationships we have been working with the joint venture partners that hold 80% of the quota (Petuna Seafoods - Les Scott and Graham Patchel and Oceanfresh -Gerry Geen) in the industry and the associated vessels the Petuna Explorer, Ocean Dawn and Aoraki. Thus far we have trialed the acoustic monitoring method on all vessels that use the same Simrad ES60 38kHz acoustic equipment that is becoming an international standard. We successfully logged data from all the vessels during the previous winter and investigated capturing other biological and physical data with associated costs.

The industry joint venture partners have been very supportive in the pilot phase and in this proposal they will provide dedicated vessel time of two weeks in the first year as well as ongoing time for dedicated surveys in the second and third year. To ensure that the monitoring system is sustainable requires forward commitments by industry and researchers. Industry are committed to supporting the acoustic monitoring project and targeted environmental monitoring both in the short and if proved successful in the long term (see separate letter). During the project the best method of ensuring ongoing collection (at appropriate standards) and analysis of the data will be investigated under two main models. Firstly, that industry become the sole people responsible for data collection, analysis and reporting. Secondly, industry engage a suitable consultant (independent or government) to manage the continued data collection to agreed protocols and analysis of data. A necessary outcome of this research will be an appraisal of the most appropriate method to transfer the methodology. This objective will continue throughout the project and a close relationship with industry maintained through the co-principle investigator “Gerry Geen”.