PROJECT NUMBER
•
1999-106
PROJECT STATUS:
COMPLETED
ORGANISATION:
CSIRO Oceans and Atmosphere Hobart
SPECIES
20,058 results
Estimation of natural and fishing mortality using length composition data
Project number:
2003-041
Project Status:
Completed
Budget expenditure:
$318,426.18
Principal Investigator:
Norman G. Hall
Organisation:
Murdoch University
Project start/end date:
28 Sep 2003
-
1 Sep 2008
Contact:
FRDC
Sound estimates of natural and fishing mortality form the basis of fishery stock assessment and modelling. Without these data, the extent to which the spawning biomass has been reduced or the effectiveness of management measures in sustaining wild fish stocks cannot be determined. These estimates of mortality are crucial if the commonly-used reference points for fishing mortality and biomass are to be used in managing fisheries. Considerable advances have been made in obtaining estimates of mortality when data on the age composition of the annual catch are available. However, when there are only data on the length composition of the catches, analyses become more complex and the algorithms are not as well defined. Although information is usually available within the biological and fishery data that allows estimation of total mortality, the information on natural mortality must usually be obtained from empirical models that relate natural mortality to characteristics of the life history for other fish species or by estimating the relationship between total mortality and fishing effort, thereby obtaining an estimate of natural mortality by subtraction. Furthermore, there is a need to understand how natural mortality varies with size. Although the study of mortality deserves to be a primary focus of fishery research, it is difficult and thus often set aside. For many of Australia’s finfish stocks, there is a need to develop length-based methods to estimate mortality, which can be used to monitor the stock status of the recreational fisheries, and to obtain improved estimates of natural mortality that can be used in assessing sustainability. The project falls within FRDC’s Natural Resources Sustainability Program and is intended to increase and apply knowledge of stock assessment methods by developing methods of estimating mortality using length composition data which, compared with age composition data, are relatively inexpensive to collect.
1. To develop methods for estimating natural, fishing and total mortality from length composition data and, in particular, to enable the following objectives to be achieved.
2. To estimate total mortality by applying Length Frequency Analysis (LFA) methods to length composition data.
3. To estimate total mortality by applying a length-based method of relative abundance analysis to length composition data from consecutive years.
4. To estimate natural mortality from the changes in length composition data that accompany a change in minimum legal length.
5. To estimate natural mortality using a length-based fishery model
6. To determine whether these length-based methods can be used to estimate a size-dependent (rather than constant) natural mortality.
Final report
ISBN:
978-0-86905-988-3
Author:
Norm Hall
Final Report
•
2017-09-29
2003-041-DLD.pdf
The objectives of this project were to develop length-based approaches for estimation of natural, fishing and total mortality, and to explore the application of these methods to the data from selected fisheries. The methods that were developed were essentially length-based versions of age-based approaches that are typically applied for stock assessment when appropriate and when representative age samples are available from either research or catch sampling.
The study explored several methods to estimate mortality from length samples. The simpler of these approaches assume that, as fishing mortality increases, fewer fish will survive to reach larger sizes. Accordingly, the size composition becomes increasingly truncated at the right when fishing mortality increases. Length FrequencyAnalysis and length-based catch curve analysis assess the extent to which the shape of the right-hand tail of the size distribution is reduced, and taking growth into account, use this information to estimate total mortality. The problem becomes more complicated, however, when annual recruitment varies. Relative Abundance Analysis attempts to track peaks and troughs in the length compositions in successive years, thereby identifying strong and weak year classes. By taking year class strength into account, the decline in the right-hand tail of the length distribution can be assessed more reliably, thereby improving the accuracy of the estimate of total mortality. An increase in minimum legal size allows smaller fish that would previously have been caught to survive and grow to the new minimum size. If there are adequate data and the change in minimum size is sufficiently great, the change in the length compositions before and after the change in minimum size can be used to estimate the natural mortality. Finally, by analyzing the combined set of time series of fishery data, length and age samples, and attempting to track year classes through the catch-per-unit-of-effort, age-composition and length-composition data in successive years, it is possible to obtain estimates of both natural and fishing mortality. The precision of the estimates is dependent of the information content of the data, however. This last analysis was extended to assess whether, for Tailor, there was evidence of length-dependent natural mortality.
The methods and software developed in this project were applied to length data for the Western Yellowfin Bream in Shark Bay, Tarwhine, Breaksea Cod, Dhufish, Snapper from NSW, Mud Crabs, King George Whiting, and Tailor. The data for King George Whiting and Mud Crabs were found to be inappropriate for analysis using the approaches developed in this study. Although catch curve and relative abundance analysis produced highly inconsistent estimates of mortality for Breaksea Cod, reasonable and realistic estimates of mortality were produced for the other species. For Tailor, it was found that the assumption of constant natural mortality resulted in a better fit of the fishery model than that which was obtained by using the length-dependent natural mortality assumption.
The analyses that were undertaken in this study demonstrated that the length-based approaches, while less precise and reliable than age-based methods, had potential for use in stock assessment. This is particularly the case for recreational fisheries, for which length samples are likely to be more readily available than age samples.
Developing integrated performance measures for spatial management of marine systems
Project number:
2004-005
Project Status:
Completed
Budget expenditure:
$805,294.00
Principal Investigator:
David C. Smith
Organisation:
CSIRO Oceans and Atmosphere Hobart
Project start/end date:
30 Aug 2004
-
30 Nov 2008
Contact:
FRDC
The need to report on the ecologically sustainable use of marine systems, that have been ‘zoned’ at a variety of spatial and temporal scales is gaining considerable support in Australia and world-wide. MPAs and other spatial management arrangements are being introduced in most Australian management jurisdictions through the NRSMPA process and at the Commonwealth level through Regional Marine Planning under Oceans Policy. Clearly, spatial management, particularly expressed as MPAs, is here to stay. For example FRDC suggests that nations will set targets such as 20% of the coastal zone for high degrees of protection through MPAs (FRDC R&D Plan 2000-2005).
The objectives of MPAs are usually to achieve ESD for the regional ecosystem and for the various sectoral users of the ecosystem. For example, the benefits to fisheries are often listed to be to increase the spawning biomass, to act as an insurance policy against fishery management errors, to protect critical habitats to damp ecosystem wide fluctuatons and to provide reference sites to be used in fishery resource assessments. However, while some studies have shown that the harvesting regimes for specific areas within a system can change biomass, density, size of organisms, quality of habitats and species diversity, the causes of the extent and nature of these changes at various spatial and temporal scales impedes the selection of performance indicators.
The use of MPAs is a relatively new approach to marine management and is at a very early stage of development. For example the use of other management tools includes the use of performance assessment and the triggering of management responses under different circumstances. In fisheries this is commonly through the periodic review of catch or fishing effort levels in relation to stock condition. The policy descriptions of the use of MPAs and spatial management, for example in Oceans Policy also makes reference to the use of such adaptive management, but the methodology to enable and guide this has not net been developed. This was highlighted at the recent World Congress on Aquatic Protected Areas and FRDC’s workshop on R & D priorities where it was clear that the current state of the science limits the ability for performance assessment.
It is not yet clear under what circumstances specific areas within large systems contribute to the system as a whole, and the way in which large system behaviour influences areas within it . Globally spatial area management, as illustrated by MPAs, is receiving considerable attention as ‘new’ tool to control over-exploitation of fish stocks (eg Pauly et al 2002). In a recent review Ward et al (2000) state that there are “...very few examples where benefits to a fishery (as opposed to the closed area ) have been well studied and documented”. Similar conclusions are being drawn in other reviews currently appearing (e.g. Halpern in press). Socio-economic impacts are even less well studied (Sanchirico 2000).
Without such performance assessment managers and resource users may become locked into sub-optimal management arrangments, and if MPAs and other area management arrangements are not working as intended then achieving goals such as Ecologically Sustainable Development may be unknowingly at risk. Consequently, even with objectives that are clearly defined and agreed by all stakeholders, the most challenging work still remains as how to evaluate performance.
Victoria is committed to range of activities to ensure marine systems are managed for ecological sustainability. Recent initiative include reforms to the management of abalone, rock lobster and the establishment of marine protected areas, these together with National Oceans Office planning for the South-East Region, provides a major opportunity for this work to be undertaken. In addition, the NOO have identified integrating fisheries spatial management and MPAs as an action in the South East Regional Marine Plan.
This project does not address whether or not there should be MPAs rather it is designed to develop an effective means to assess the performance of the system and the MPA within it. We will build on previous work but more importantly extend the scope to include fishery ecosystem considerations as well as direct impacts on target species and biodiversity.
1. Through an analysis of monitoring data from existing marine system management egimes (including MPAs) and an identification of observational approaches that are available to be used, develop simple biophysical and management models of impact and response at various spatial scales.
2. Use these models to develop and evaluate measures to report performance for specified management objectives particularly in respect of power to detect change.
Final report
Spawning and larval recruitment processes of commercially important species in coastal waters off Victoria
Project number:
1996-116
Project Status:
Completed
Budget expenditure:
$197,820.00
Principal Investigator:
Francisco Neira
Organisation:
Agriculture Victoria
Project start/end date:
29 Dec 1996
-
30 May 2000
Contact:
FRDC
1. To collect ichthyoplankton and physical, chemical and oceanographic data in Bass Strait during the winter of 1997 and the summer of 1997/98.
2. To describe the composition, abundance and spatial distribution of fish eggs and larvae, with particular reference to the early stages of commercially-important inshore fish species and those of the south-east trawl fishery.
3. To determine the areas and season of the spawning of King George whiting (Sillaginodes punctata) off the Victorian coast.
4. To determine the abundance of the different developmental stages of King George whiting at different locations and identify the possible occurrence of larval transport by back calculating the age of larvae.
5. To determine the areas and season of spawning of pilchards (Sardinops sagax) off the Victorian coast and to describe the horizontal and vertical distribution of eggs and larvae.
6. To identify regions of changing nutrient and chlorophyll concentration, and their relationship to physical properties (S,T) and ichthyoplankton abundance.
7. To collect physical oceanographic data and satellite images to extend the 3-D Bass Strait hydrodynamic model of coastal currents.
8. To describe the spatial and seasonal distribution of rock lobster phyllosomes and giant crab megalopa.
Final report
ISBN:
0-7311-4611-5
Authors:
Dr Francisco J. Neira
Dr Gregory P. Jenkins
Mr Andrew Longmore
Dr Kerry P. Black
Final Report
•
2011-07-11
•
7.90 MB
1996-116-DLD.pdf
Information on spawning and larval recruitment processes of commercially important species in coastal waters in south-eastern Australian waters is provided based on four daytime surveys carried out on board the RV Franklin during the summer of 1997 (January-February and December) and the winter of 1998 (May-June and July). The principal objective of the project was to locate main spawning areas of commercial fish species, and to combine fish eggs and larval concentrations with hydrographic ( currents, density) and hydrochemical (inorganic nutrients, fluorescence, chlorophyll a) data in an attempt to identify possible retention areas and advection pathways of larvae. All specific objectives of the project were accomplished to varying degrees of success, except those stated above in 7 since no specimens were obtained.
PROJECT NUMBER
•
2006-026
PROJECT STATUS:
COMPLETED
ORGANISATION:
McPhee Research Consultants Pty Ltd
Can production in the southern rock lobster fishery be improved? Linking juvenile growth, survival and density dependence to sustainable yield
Project number:
2001-070
Project Status:
Completed
Budget expenditure:
$471,134.00
Principal Investigator:
David Hobday
Organisation:
Agriculture Victoria
Project start/end date:
30 Dec 2001
-
22 Apr 2006
Contact:
FRDC
SPECIES
Across all southern states there is a strategic need for research to improve assessment of the stocks, improve advice on management alternatives, and provide forecasts with reduced uncertainty of future stock size and,by implication, potential catches (see attached figure 1). This proposal addresses this need.
In all states current management objectives include rebuilding of the stocks. Current legal sized biomass is principally based on recent recruits to the fishery. As stocks rebuild, the biomass will contain a greater proportion of lobsters that had recruited prior to the last season. As these lobsters will have increased in size since recruiting, the average weight of the legal sized biomass will have increased. Thus bigger stocks will certainly provide greater yields from each recruit and therefore lead to greater productivity. As the number of eggs that a female lobster broods is a cubic relationship to her size, a small increase in size will lead to a much larger increase in the number of eggs produced. Thus large gains may also be possible through the feedback from greater egg production from the rebuilding legal sized biomass. The potential for more eggs to lead to higher recruitment to the fishery will be strongly dependent on the rates of growth and mortality of the pre-recruit stages. Therefore there is a need to acquire this information to enable managers to take egg production into account when setting management measures.
Tasmania is about to start a puerulus harvesting program as part of an attempt to establish a rock lobster aquaculture industry in the state. Part of this activity is a return of a proportion of the animals to the wild after a period in the laboratory, estimated to be equal or in excess of those that would have survived over a similar period in the wild. This aims to ensure neutrality of puerulus harvest. The return is currently based on "guesstimates" of mortality. The results of this study will therefore have a significant application in this related work.
The high value of rock lobster fisheries in southern Australia means that even small increases in the catch may have substantial benefits. A 5% improvement might result in a $10 million increase in landed value with flow on benefits to southeastern Australian rural coastal communities. Concern has been voiced that increases in production may be offset by lower prices due to supply outstripping demand. However, price increases during the past decade suggest that demand is growing more rapidly than supply. It therefore seems reasonable to conclude that higher production (without increased effort) in southern Australia will have a positive impact on the economy.
1. To determine growth and mortality rates of juvenile (<
80mm) lobsters throughout the range of the commercial fisheries.
2. To assess if increased juvenile density will translate to increased fishery production.
3. To evaluate techniques and obtain preliminary estimates of growth and mortality rates of puerulus / post-puerulus.
Final report
Monitoring and assessment of management policies in the northern prawn fishery
Project number:
1985-081
Project Status:
Completed
Budget expenditure:
$0.00
Organisation:
Department of Agriculture, Fisheries and Forestry (DAFF) ABARES
Project start/end date:
28 Dec 1987
-
31 Dec 1987
Contact:
FRDC
1. Develop a model for analysis of current boat replacement policy & the VLEBBS under both different scenarios. Establish a system to obtain key economic data. Provide analyses on management policies much earlier than under previous approaches.
Final report
ISBN:
0 644 078 17 0
Author:
Jos Haynes
Sean Pascoe
Final Report
•
2017-09-29
•
10.17 MB
1985-081-DLD.pdf
The northern prawn fishery has been subject to management since the early 1970s in an attempt to control the expansion of effort and prevent the overexploitation of the resource. Many of the management policies developed over this period have proved to be ineffective in controlling effort. Moreover, the increasing cost of management and the need to avoid costly and ineffective measures will lead to increasing demands for analysis of the cost effectiveness of such policies. In order to assess the effects of current and alternative management policies on both effort and profitability in the fishery, a mathematical programming model of the fishery was developed in the Bureau's Fisheries Economics Research Section. This report outlines the model and assesses the short and long term effects of the current and alternative management policies on the fishery.
Tactical Research Fund: cost-benefit analysis of implementing alternative techniques for rehabilitating reefs severely depleted by Abalone Viral Ganglioneuritis epidemic
Project number:
2008-076
Project Status:
Completed
Budget expenditure:
$43,010.43
Principal Investigator:
Harry F. Peeters
Organisation:
Western Abalone Divers Association (WADA)
Project start/end date:
30 Nov 2008
-
27 May 2009
Contact:
FRDC
In May 2006 an epidemic caused by Abalone Viral Ganglioneuritis (AVG) began infecting wild stocks of abalone in the Victorian western zone, rapidly spreading through the zone causing mortality rates of 40-95%. In response infected reefs have been closed since infection and to date remain closed resulting in the zonal TAC being reduced by >90%. It is the observation of WADA’s divers that, having been closed to fishing for several years, the reefs that suffered relatively lower mortality rates (75%) are, to this time, recovering well. Supported by an FRDC TRF project ‘Indicators and strategies for resumption of harvesting following catastrophic loss of abalone’ WADA members agreed that these ‘lightly’ impacted reefs should be closed for at least threes closure before being re-opened (some in 2009) with conservative size limits and catches.
In contrast to reefs that suffered relatively low mortality rates WADA’s divers observe that a number of formerly important reefs which suffered high mortality rates (>90%) do not appear to be recovering. Worryingly Californian studies suggest disease related reductions of abalone grazing pressure can lead to overgrowth of suitable settlement surfaces which retards natural rates of re-colonisation. WADA estimates one ‘high mortality’ reef, Kilarney, lost 100-200t of biomass and members are concerned that without intervention there will be a semi-permanent loss of productivity from some important reefs.
To prevent this WADA’s members are discussing initiating in 2009 rehabilitation projects for heavily impacted reefs by alternatively:
• Re-seeding of hatchery produced juveniles,
• Translocation of adults from other reefs in the western zone
• Long term closure to allow natural recruitment processes.
A cost-benefit analysis of alternative rehabilitation techniques is needed to inform members of the relative merits of alternative rehabilitation techniques and the likely magnitude of cost for rehabilitating at the scale of entire reefs.
1. Synthesis available data on reseeding, translocation and natural rebuilding of abalone.
2. Construct a quantitative economic and population dynamics model of reseeding, translocation and natural rebuilding for blacklip abalone reefs and use it to analyse the likely costs and benefits of alternative techniques of rehabilitating the Kilarney reef code in the Victorian western zone.
3. Prepare and present a written and audio-visual report to WADA at their October 2008 and February 2009 reef assessment workshops detailing modelling methods, underlying assumptions and results of evaluating alternative rehabilitation techniques.
Final report
Atlantic Salmon Aquaculture Subprogram: Forecasting ocean temperatures for salmon at the farm site
Project number:
2010-217
Project Status:
Completed
Budget expenditure:
$45,000.00
Principal Investigator:
Alistair Hobday
Organisation:
CSIRO Oceans and Atmosphere Hobart
Project start/end date:
9 Oct 2010
-
29 Sep 2011
Contact:
FRDC
This proposal is in response to requests from salmon companies to provide short-term ocean forecasts for Tasmanian farm sites. With this information, they can plan operations in the upcoming months, in particular stocking rates, disease treatments, and staffing levels for cage maintenance.
1. Generate site specific seasonal water temperature statistical forecasts for three nominated farm sites.
2. Generate and test the skill of dynamical regional ocean forecasts using the BOM seasonal prediction model (POAMA)
3. Undertake cost-benefit analysis of the value of these short-term predictions for the salmon industry
Final report
ISBN:
978-1-921826-70-2
Author:
Alistair Hobday
People development program: 2014 FRDC Visiting Expert Award- Dr Dan Gwinn
Project number:
2008-328.22
Project Status:
Completed
Budget expenditure:
$9,972.00
Principal Investigator:
Brett Ingram
Organisation:
Agriculture Victoria
Project start/end date:
30 Jun 2014
-
29 Jan 2015
Contact:
FRDC
Dan Gwinn is an internationally renowned quantitative ecologist with technical expertise in several key areas that will benefit the management of Australia’s fisheries. Of particular interest to FRDC are his expertise in parameter estimation, monitoring design, and fisheries modeling. Dr Gwinn is experienced in developing innovative estimation methods to specifically deal with the inherent issues with imperfect data as is the case for fisheries and ecological research. Dr Gwinn’s work in this area has focused on the customization of statistical models to account for the specific idiosyncrasies of data sets to best extract biological information and inform the management decision process. Often, this work had included developing innovative analyses of existing data sets to answer new questions. Dr Gwinn also has expertise in use of analysis tools including the application of stochastic simulations for evaluating and optimizing experimental and monitoring designs, which are particularly useful for determining the most fiscally efficient sampling designs for meeting monitoring objectives.
We propose to facilitate a study tour for Dr Gwinn to enable him to meet with fisheries researchers and managers from several jurisdictions to review and discuss key freshwater and marine projects, present to the research and management community on innovative methods being employed in the United States to address common issues, and workshop strategies to enhance adoption of R&D outputs.
We believe that this visit will deliver significant benefit to the future management of Australia's fisheries resources.
1. To enable Dr Dan Gwinn to meet with Australian leaders in fisheries research and management as part of a coordinated program of meetings, workshops and presentations, to optimise outcomes delivered for high profile/value species and fisheries in eastern Australia.
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