Project number: 2003-075
Project Status:
Budget expenditure: $570,080.00
Principal Investigator: Yimin Ye
Organisation: CSIRO Oceans and Atmosphere Hobart
Project start/end date: 30 Aug 2003 - 30 Sep 2005


An international review of the NPF tiger prawn assessment agreed with the conclusions of the 2001 assessment that tiger prawn levels are critically low, especially for brown tiger prawns. The 2002 assessment has further concluded that brown tiger prawn levels are too low but has also emphasized the critical need for an independent monitoring program given the confounding and complexities of the catch rate data used as the sole index of abundance in the NPF assessments.

The survey data used to determine the initial design for this project (see Background) is more than a decade old and does not cover the full study area. Therefore the initial surveys will be largely exploratory in nature and very much a trial to see if the proposed design is effective. Also, the survey design includes integrated components such as the assessment of long-term changes in fishing power and the contraction of the fishery over time that have not been undertaken in prawn survey designs (both nationally and internationally) before. These aspects highlight that this project has a large research component; the appropriate survey design is still being developed and methods for incorporating the results of the surveys into future stock assessments need to be developed.

In this proposal, the CSIRO salaries associated with modifying the survey design and with developing new methods of incorporating the results into stock assessments are seen as research. We are therefore requesting about $60,000 from FRDC’s MOU funds. For this reason, CSIRO is also supporting the project to the scale of about $87,000. The remainder of the project, some $510,000, will be underwriten by the industry as agreed in NORMAC, June 2003. The industry and NORMAC have also re-affirmed the long-term need for regular industry-funded monitoring surveys based on the output of this project.

There is a need to provide an updated design for the NPF that would work in the long-term to provide indices of abundance to key species and enhance a difficult-to-use commercial catch rate series. Furthermore, this design needs to address target, byproduct and possibly some effects-of-trawling issues to make the best use of the surveys, as they will be a large expense to the industry.


1. To determine the final design and analyses for two surveys in the Gulf of Carpentaria
2. To undertake a survey in August 2003 to provide biomass and spawning indices of the main commercial prawn species in the Gulf of Carpentaria
3. To undertake a survey in January/February 2004 that will provide a recruitment index of the main commercial prawn species in the Gulf of Carpentaria
4. To determine the appropriate scale and frequency of future surveys
5. To spatially map the distribution of the main prawn and byproduct species in the Gulf of Carpentaria

Final report

ISBN: 1-876-996-81-1
Author: Yimin Ye
Final Report • 2005-09-08


For more than a decade the Northern Prawn Fishery assessments have indicated that the tiger prawn resource is overexploited. Deriso’s1 (2001) review of the tiger prawn assessment supported this conclusion and also drew attention to the high level of uncertainty in the assessment. Deriso strongly recommended that the logbook data be augmented by fishery-independent survey data and that the survey should be designed both to provide an independent index of abundance for each tiger prawn species and to quantify fishing power changes. The clear message of the review was that a survey program is an essential investment for this fishery.
In response to this review, an initial industry-funded (Dichmont et al. 2002) consultancy was established to investigate and design an integrated monitoring program for the NPF.  The initial design results were presented to a well-attended industry meeting in Cairns in February 2002.  Suggestions from industry were incorporated into the project and a final report included a modular design and costing structure, which was presented to a special NORMAC meeting in March 2002.  This meeting agreed to all components of the proposed program except the work in Joseph Bonaparte Gulf, which was seen as premature. As a result of this decision, a one year pilot test of the desk top design was undertaken incorporating two trawl surveys in 2002/03 (Dichmont et al. 2003). The first, aimed at estimating a spawning index that could also be used in future fishing power studies, was undertaken in 3 regions of the Gulf of Carpentaria (GOC) in August 2002. The second survey aimed to produce an index of recruitment and was undertaken throughout most of the fishing regions of the Gulf of Carpentaria in January/February 2003.  The final funding mix, based on an assumption of a 50:50 ratio of monitoring to research, was 50% industry funded and the remainder equally funded by AFMA Research Fund, FRDC and CSIRO.
The current project (FRDC 2003/075) aims to continue the surveys, finalize the design and develop techniques that can effectively use the survey data to improve stock assessment. 

Related research


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NPF Industry Pty Ltd