3 results

Utilisation of GIS spatial statistical methods to assist in the development of ecosystem based fishery management strategies using the Northern Territory demersal and Timor Reef fisheries as case studies

Project number: 2005-047
Project Status:
Completed
Budget expenditure: $73,188.04
Principal Investigator: Julie Martin
Organisation: Department of Agriculture and Fisheries (NT)
Project start/end date: 30 Jul 2005 - 30 Aug 2007
Contact:
FRDC

Need

There is a need to develop a holistic approach to fisheries management and to understand what effect fishing has on the entire ecosystem; this is the basis of Ecosystem Based Fishery Management (EBFM). However present methods are not well suited to addressing this problem, hence the need to develop new techniques that can analyse the complex interactions and relationships that occur within an ecosystem. We believe that GIS spatial statistical methods have the potential to address some aspects of this problem. Moreover GIS has the ability to address the additional problem of utilising information that occurs at different spatial scales.

Although many fisheries are multi-species, they are normally managed as if they were single species fisheries, focused on the target species. For more effective management of multi-species fisheries and to meet ESD requirements there is a need to be able to observe what effect management strategies have on the suite of species within a fishery. There is also a need to be able to determine effective “trigger” or “response” points for a fishery, often with only a small amount of biological information. From the preliminary work already undertaken we believe that GIS spatial statistical methods are well suited to meet these requirements and support an Ecosytem Based Fishery Management approach.

There is a need to discern between what effect environmental influences are having on fish catches in order to ascertain whether a decrease in catch rates is due to declining fish stocks or the result of a temporary decrease in catchability due to environmental conditions. The techniques proposed in this application are well suited to determining this.

Present indications are that a decline in abundance of goldband snapper is occurring on small spatial scales in some prime fishing areas in the Timor Sea. Do these declines represent fishing down to sustainable productive levels on local scales or significant reductions relative to the whole of the population? This project will address this need by using all available information to determine areas where goldband snapper is likely to be concentrated.

There is also a need to be able to utilise disparate data sets. This is an important consideration given the high cost of fisheries research and diminishing research budgets. Now researchers must be able to maximise the use of all available data, including historical data. Often this data has been collected on different spatial scales, making analysis difficult using conventional methods. However GIS is well suited to handling data from different sources and on different spatial scales.

There is a need to develop methods of analysing and presenting data that will allow stakeholders to participate more fully in the assessment process. This will also allow scientist to obtain feedback about their interpretation of data earlier in the process rather than when the final report is delivered. We believe GIS spatial statistical methods provide an effective mechanism to facilitate this process, which will allow stakeholders to have greater participation in policy formulation and decision making.

Objectives

1. Develop new techniques using GIS spatial statistical methods, to analyse the complex interactions and relationships that occur within an ecosystem, enabling managers to develop an Ecosystem Based Fishery Management approach.
2. Develop indices of over-harvesting risks and develop trigger points , especially for multi-species fisheries.
3. Develop spatial statistical techniques to determine relationships between habitat, environmental conditions and catch rates in the Timor Reef fishery.
4. Create, in an Scilab environment, fuzzy rule-based predictive models that incorporates existing data, indices derived from spatial analysis and human knowledge.
5. Develop visual methods using GIS techniques and Fuzzy rule-based modeling systems that allow stakeholders to have greater participation in the interpretation of information and the management process.

Final report

Stable isotope tracing of the contribution of seagrass production to subtropical fisheries species occurring outside seagrass areas

Project number: 1999-217
Project Status:
Completed
Budget expenditure: $90,100.00
Principal Investigator: Rod Connolly
Organisation: Griffith University Nathan Campus
Project start/end date: 12 Jul 1999 - 30 Jul 2003
Contact:
FRDC

Need

An examination of which fisheries species are sustained by seagrass plant production has been highlighted as a major research priority in the recent reviews of fisheries habitat research gaps by Cappo et al. (1997) and Butler & Jernakoff (draft report to FRDC). The recommended method in Butler & Jernakoff for tracing seagrass production to fisheries species is stable isotope analysis. Coastal and fisheries managers currently consider seagrass to be valuable, nevertheless there are many seagrass meadows under threat and still being lost. An argument can be developed, supported by current scientific evidence, that many important fisheries species are not reliant on seagrass and that their numbers actually increase upon the decline of seagrass. Estuarine and offshore fisheries species that do not appear to be dependent on seagrass might actually be so, but indirectly; they may be deriving their food from animals in a trophic web that is sustained by energy (carbon) and nutrients (e.g. nitrogen) transported from seagrass meadows. Another estuarine habitat, mangrove forest, has previously been touted as generating plant production that drives food webs elsewhere in estuaries and offshore. Recent evidence from Australia and Asia suggests this is not so; mangroves seem to sustain only species living in mangrove areas. The question whether seagrass production is the major source of primary production sustaining fisheries production needs answering. The best method for tracing where fisheries species gain their nutrition is stable isotope analysis.

The proposed research will be done in Moreton Bay and Hervey Bay. These bays are of extraordinary importance to Queensland fisheries, with Moreton Bay alone comprising up to 30% of the total Queensland catch of inshore recreational and commercial species (Tibbetts & Connolly 1998). There are also important fisheries in deeper waters adjacent to these bays. Both bays have extensive areas of seagrass, but also mangroves, saltmarsh and occasional reefs offshore. They are also suffering ongoing seagrass loss.

Objectives

1. Determine the ultimate source of primary (plant) production sustaining fisheries production of several key species of fish and crustaceans in subtropical Australian waters.
2. Quantify the contribution of seagrass meadows to fisheries species found outside seagrass areas, either elsewhere in estuaries or offshore.
3. Ensure that information about the relative importance of seagrass to production in different fisheries is taken to fisheries and other coastal managers to influence future management decisions.

Final report

ISBN: 0-909291-73-X
Author: Rod Connolly
Final Report • 2003-07-16 • 1.33 MB
1999-217-DLD.pdf

Summary

Results from this project affect the relative importance coastal managers will place on different estuarine habitats.  Until now primary production from mangrove forests has been ranked highly for its presumed contribution to fisheries species occurring seaward of mangroves.  This project has shown, however, that in subtropical Australian estuaries and bays, fish and crustaceans caught over shallow mudflats are much more likely to obtain substantial nutrition from seagrass meadows and in situ production of microalgae.  Mudflats lacking conspicuous vegetation not only provide habitat for certain key fish and crustacean species but also seem to play an important trophic role.  The project also developed quantitative techniques for analysing stable isotope data.  These have already been taken up by other scientists, and will help them answer big picture questions about fisheries foodwebs that have appeared intractable.
View Filter

Species