Abundance, Population Modelling, And Potential Biological Removal Estimates For Common Dolphins In Spencer Gulf: Implications For The South Australian Sardine Fishery
Funder
Fisheries Research and Development Corporation
Funding Amount
$380,000.00
Summary
This project is needed to assess the impacts of the South Australian Sardine Fishery (SASF) on the common dolphin (Delphinus delphis). The SASF is Australia’s largest volume fishery and is critical to providing a supply of feed for the ranching of southern bluefin tuna. Operational interactions between common dolphins and the SASF have been persistent since the development of the fishery. Common dolphins occasionally become encircled in purse seine nets during fishing operations, which can lead ....This project is needed to assess the impacts of the South Australian Sardine Fishery (SASF) on the common dolphin (Delphinus delphis). The SASF is Australia’s largest volume fishery and is critical to providing a supply of feed for the ranching of southern bluefin tuna. Operational interactions between common dolphins and the SASF have been persistent since the development of the fishery. Common dolphins occasionally become encircled in purse seine nets during fishing operations, which can lead to their injury and death. Observations of high interaction rates from an initial observer program, led to the temporary closure of the fishery in 2005 while an industry Code of Practice (CoP) to reduce dolphin interactions was developed. Since then, the CoP has been reviewed and refined to increase its effectiveness in preventing dolphin interactions, and improve release procedures. An independent on-board observer program has operated in the fishery since July 2006. It collects information on dolphin interaction and mortality rates, as well as data relating to the application of the CoP, and this information is provided in annual assessment reports. Since the introduction of the CoP, dolphin encirclement and mortality rates have declined, however, concerns about the level of interactions and mortality have persisted, with industry facing sustained pressure to demonstrate that steps taken to manage and mitigate dolphin interactions represent World’s best practice, and are sustainable.
This project is needed to address Marine Stewardship Council Fishery Assessment recommendations for the SASF to collect adequate and sufficient quantitative information to assess the consequences of interactions with common dolphins on their populations. This project is needed to provide an important Australian fisheries test-case for meeting new US Government legislation, requiring nations importing seafood to demonstrate that they have a regulatory program for reducing marine mammal bycatch that are comparable in effectiveness to US standards. Objectives: 1. Estimate the abundance of common dolphins in core fishing areas of the SASF 2. Collect critical life history (longevity, age specific mortality) information from museum specimens 3. Develop population models to evaluate bycatch limits of common dolphins and assess the sustainability of interactions with the SASF Read moreRead less
ARC Centre of Excellence in Population Ageing Research. This Centre intends to generate crucial knowledge to inform social and economic responses to population ageing, one of the most important issues of the 21st century. Population ageing exerts unprecedented pressures on social norms and policy institutions, both in Australia and around the world. Leading researchers from a range of disciplines will undertake multidisciplinary research to help governments, businesses, and consumers prepare for ....ARC Centre of Excellence in Population Ageing Research. This Centre intends to generate crucial knowledge to inform social and economic responses to population ageing, one of the most important issues of the 21st century. Population ageing exerts unprecedented pressures on social norms and policy institutions, both in Australia and around the world. Leading researchers from a range of disciplines will undertake multidisciplinary research to help governments, businesses, and consumers prepare for and make better decisions for an ageing world, with consequent social and economic benefits for families and communities expected to flow to Australia, the Asian region and the world.Read moreRead less
Postgraduate Funding - Population Biology And Dynamics Of Yellowfin Whiting
Funder
Fisheries Research and Development Corporation
Funding Amount
$75,000.00
Summary
The South Australian Marine Scalefish Fishery (MSF) is the most complex fishery in South Australia and is currently undergoing transition through structural reform, development of new harvest strategies and review of the Management Plan. Changes in the dynamics of the fleet have resulted in redirection of effort from primary species such as garfish, snapper and King George whiting towards secondary species including yellowfin whiting.
Yellowfin whiting Sillago schomburgkii is the second ....The South Australian Marine Scalefish Fishery (MSF) is the most complex fishery in South Australia and is currently undergoing transition through structural reform, development of new harvest strategies and review of the Management Plan. Changes in the dynamics of the fleet have resulted in redirection of effort from primary species such as garfish, snapper and King George whiting towards secondary species including yellowfin whiting.
Yellowfin whiting Sillago schomburgkii is the second most valuable Sillaginid after King George whiting and one of the most valuable secondary species in the MSF fishery with most catches from Northern Spencer Gulf, and smaller catches from the West Coast, Southern Spencer Gulf, and Gulf St Vincent. There are also significant recreational catches (31.5% of State catch in 2013/14).
There is a need for improved understanding of the life-history of yellowfin whiting with quantitative estimates of population dynamics including reproduction, growth performance and stock structure. Oceanographic separation of Spencer Gulf and Gulf St Vincent suggests that yellowfin whiting may constitute separate stocks in these regions while possible population sub-structuring occurring at smaller scales has implications for fishery management. There is potential to compare results of the proposed study with previous work to investigate whether decadal changes in the demography and population dynamics of yellowfin whiting have occurred in the South Australian Gulfs, as well as potential factors driving any change.
This project proposal aims to (i) build the capacity for scientific investigation of finfish species in South Australia by providing an opportunity for a science graduate to develop skills in fishery science, (ii) improve the understanding of life-history and population dynamics of yellowfin whiting, and (iii) improve understanding of the stock structure of yellowfin whiting. This project will have linkages to another FRDC funded project (2017/023), “ESD risk assessment for under-utilised species to facilitate structural reform of South Australia’s commercial Marine Scalefish Fishery”.
Objectives: 1. Define the stock structure of yellowfin whiting in South Australia and the relationship to Western Australian stocks using genomic approaches. 2. Define finer scale population structure of yellowfin whiting in the South Australian gulfs using otolith chemistry. 3. Examine spatial and temporal trends in catch among yellowfin whiting and other species in the marine scalefish fishery and how representation among different life-history strategy groups has changed. 4. Investigate size and age structures of yellowfin whiting in the two gulfs of SA and how these have changed over a 22 year period. 5. Increase fisheries science capacity in South Australia through training of the next generation of researchers. Read moreRead less
Developing And Validating Novel Methods To Estimate Age- And Size-at-maturity In South Eastern Australian Fisheries
Funder
Fisheries Research and Development Corporation
Funding Amount
$348,420.00
Summary
We submit this EOI to the priority ‘Biological parameters for stock assessments in South Eastern Australia – a information and capacity uplift’
Empirical observations from around the world have shown that intense fisheries harvest and oceanic warming can both lead to individuals reaching sexual maturity at younger ages and smaller sizes (Waples and Audzijonyte 2016). We know that younger and smaller mothers produce fewer eggs that may be of poorer quality than those from older and lar ....We submit this EOI to the priority ‘Biological parameters for stock assessments in South Eastern Australia – a information and capacity uplift’
Empirical observations from around the world have shown that intense fisheries harvest and oceanic warming can both lead to individuals reaching sexual maturity at younger ages and smaller sizes (Waples and Audzijonyte 2016). We know that younger and smaller mothers produce fewer eggs that may be of poorer quality than those from older and larger mothers (Barneche et al. 2018). Further, young mothers often need to build up their energy reserves before spawning each year, meaning that they experience a constrained spawning season. A shorter spawning window reduces the likelihood that their offspring will encounter an environment favourable for growth and survival (Wright and Gibb 2005). Harvest-induced declines in age and size at maturity have, for example, been implicated as one of the main drivers underpinning the collapse of Canadian Atlantic cod stocks (Hutchings and Rangeley 2011).
Environmental stress can also lead to poorer conditioned fish that lack the resources to spawn at all. The prevalence of ‘skip spawning’, as it is known, is hard to ascertain in wild populations but could be as high as 30% of the sexually mature biomass in some years (Rideout and Tomkiewicz 2011). Earlier maturity and skip spawning both have the potential to significantly impact on the biomass of sexually mature individuals in a stock and overall levels of recruitment success. Failure to properly account for these reproductive phenomena can lead to significant under- or over-estimation of SSB, which in turn leads to ineffective management advice that may heighten the risk of stock decline, unnecessarily limit catches, or impede stock recovery.
The rapid warming of southeast Australian waters has already been implicated in driving significant increases in the juvenile growth rates of harvested species, including tiger flathead, redfish and jackass morwong (Thresher et al. 2007, Morrongiello and Thresher 2015). It is plausible that these growth changes (predicted by eco-physiological theory, Atkinson 1994) are linked to commensurate, yet unknown, declines in age and size at maturity. Further, warmer waters may be stressing spawning adults (Portner and Farrell 2008), leading to an increased prevalence of skip spawning in southeast Australian fishes. Importantly, in recent times the biomass of several SESSF species has failed to recover despite significant management intervention. There is a real and pressing need to update the maturity parameters used in assessment models to reduce uncertainty in stock projections.
Our two-part project will refine and validate novel otolith-based methods to estimate an individual’s age at maturity and spawning dynamics from information naturally recorded in its otolith, and then apply this to existing otolith collections. AFMA already invests significant resources into the routine collection of otoliths for ageing purposes. In Part One of our project, we propose to value-add to these existing monitoring programs by developing new maturity and spawning assays that can be readily integrated into stock assessments to reduce model uncertainty and improve harvest strategies (FRDC strategic outcome 2 & 4), in turn bolstering community trust in projections (FRDC strategic outcome 5). In Part Two of our project, we will develop unprecedented insight into the reproductive history of SESSF stocks by recreating time series of maturity using archived otoliths that are currently sitting idle in storage.
Postgraduate students and early career researchers will play a central role in the development and delivery of our project. This experience will help provide a clear pathway for graduates into fisheries science. Our project will bolster the capacity and capability of fish ageing laboratories across Australia to deliver improved monitoring services to fisheries managers (FRDC enabling strategy IV).
More generally, we believe that our novel maturity and spawning assays have the potential to impact on fisheries assessment in other jurisdictions across the world that experience the same time and cost impediments we face here in Australia. Perhaps most excitingly, our assays have the potential to provide much needed maturity information to data poor and emerging fisheries across the Info-Pacific region using information in already collected otoliths.
References Atkinson, D. 1994. Temperature and organism size: a biological law for ectotherms? Advances in ecological research 25:1-58. Barneche, D. R., D. R. Robertson, C. R. White, and D. J. Marshall. 2018. Fish reproductive-energy output increases disproportionately with body size. Science 360:642-645. Hutchings, J. A., and R. W. Rangeley. 2011. Correlates of recovery for Canadian Atlantic cod (Gadus morhua). Canadian Journal of Zoology 89:386-400. Morrongiello, J. R., and R. E. Thresher. 2015. A statistical framework to explore ontogenetic growth variation among individuals and populations: a marine fish example. Ecological Monographs 85:93-115. Portner, H. O., and A. P. Farrell. 2008. Physiology and climate change. Science 322:690-692. Rideout, R. M., and J. Tomkiewicz. 2011. Skipped spawning in fishes: more common than you might think. Marine and Coastal Fisheries 3:176-189. Thresher, R. E., J. A. Koslow, A. K. Morison, and D. C. Smith. 2007. Depth-mediated reversal of the effects of climate change on long-term growth rates of exploited marine fish. Proc. Natl. Acad. Sci. U.S.A. 104:7461-7465. Waples, R. S., and A. Audzijonyte. 2016. Fishery-induced evolution provides insights into adaptive responses of marine species to climate change. Front. Ecol. Environ. 14:217-224. Wright, P. J., and F. M. Gibb. 2005. Selection for birth date in North Sea haddock and its relation to maternal age. Journal of Animal Ecology 74:303-312.
Objectives: 1. Refinement and validation of three methods to estimate the maturity and spawning history of SESSF species, using information naturally archived in fish otoliths 2. Identification of an accurate and cost-effective method to estimate fish age at maturity and spawning history from their otoliths 3. Recreation of the maturity and spawning history of a SESSF species using one of our three novel assays 4. Quantification of how rapid ocean warming and harvest have affected the expression of age at maturity and the propensity of a SESSF species to skip spawn Read moreRead less
Developing A Cost-efficient Stock Assessment Program For Southern Calamari Fisheries
Funder
Fisheries Research and Development Corporation
Funding Amount
$496,827.00
Summary
Southern Calamari are important to multiple commercial and community fishery sectors in SA. Southern Calamari are now managed using a TACC for the commercial MSF and have specified resource allocations for recreational, Aboriginal/Traditional, Charter Boat, GSV prawn and SG prawn fisheries. However, the current assessment program does not capture the importance of this species and cannot support the level of management required. The primary outcome of this project will be to develop an assessmen ....Southern Calamari are important to multiple commercial and community fishery sectors in SA. Southern Calamari are now managed using a TACC for the commercial MSF and have specified resource allocations for recreational, Aboriginal/Traditional, Charter Boat, GSV prawn and SG prawn fisheries. However, the current assessment program does not capture the importance of this species and cannot support the level of management required. The primary outcome of this project will be to develop an assessment program for Southern Calamari in SA that can be used to assign stock status and provide TACC setting advice to fisheries management.
Like many cephalopod assessments, the current SA Southern Calamari assessment is basic as scientific advances have not occurred at the same rate as advances for finfish or crustacean assessment methods. Therefore, the successful development of an assessment program for Southern Calamari in SA would provide a valuable scientific contribution to several other Australian squid fisheries as they often encounter similar assessment difficulties
Overcoming key knowledge gaps and incorporating information on environmental drivers will be a key focus of this project, in order to develop an assessment that accounts for the full complexity of cephalopod population dynamics. However, there are limited resources to undertake an assessment in SA as the commercial MSF has a low gross value product (GVP) but has high assessment needs across several species. Therefore, a cost-effective assessment program must be developed to allow for its regular application, which is necessary for short lived species such as Southern Calamari.
The proposed project will address two FRDC strategic plan outcomes (Growth for enduring prosperity, and best practices and production systems) by developing a best practice assessment program that can be applied for Southern Calamari in SA and be extended for use in other fishery jurisdictions. An assessment program that provides confident management advice, such as TACC setting, will maximise resource use across all sectors by establishing a robust stock assessment that increases certainty in stock abundance and allows sustainable fishing strategies to be developed.
Objectives: 1. Review global cephalopod assessments to identify potential assessment methods for Southern Calamari and how environmental variables could be incorporated. 2. Evaluate the suitability of available fishery-dependent and fishery-independent data from the SG and GSV prawn fisheries to develop recruitment indices. 3. Develop Southern Calamari growth models for SG and GSV and evaluate the influence of environment on seasonal growth rates. 4. Outline the most suitable and cost-effective assessment program option for Southern Calamari in SG and GSV Read moreRead less
Financial decision making in late adulthood. The project aims to examine links between cognitive changes and financial decision-making in late adulthood and also to assess the preparedness of the elderly to combat financial risks due to age-related cognitive decline. Further, it intends to examine how age, education, wealth, health, and other environmental factors influence transfer of financial decision-making responsibilities to spouses or others. It is expected that the research will provide ....Financial decision making in late adulthood. The project aims to examine links between cognitive changes and financial decision-making in late adulthood and also to assess the preparedness of the elderly to combat financial risks due to age-related cognitive decline. Further, it intends to examine how age, education, wealth, health, and other environmental factors influence transfer of financial decision-making responsibilities to spouses or others. It is expected that the research will provide a greater understanding of how cognitive functioning and other factors affect older adults’ financial capacity and willingness to delegate decision-making responsibilities. This understanding could be used to inform policy initiatives to protect elderly individuals and their family members from the risk of financial mismanagement.Read moreRead less
Snapper Science Program: Theme 1 - Biology And Ecology
Funder
Fisheries Research and Development Corporation
Funding Amount
$1,982,523.00
Summary
A comprehensive understanding of the general biology and ecology of any fishery species is fundamental to determine its response to exploitation and inform appropriate fishery management. Despite the significant body of research into the biology of Snapper, there remain considerable knowledge gaps regarding the underlying factors that drive interannual variation in juvenile recruitment and the demographic processes that maintain populations. Furthermore, there is uncertainty in how these process ....A comprehensive understanding of the general biology and ecology of any fishery species is fundamental to determine its response to exploitation and inform appropriate fishery management. Despite the significant body of research into the biology of Snapper, there remain considerable knowledge gaps regarding the underlying factors that drive interannual variation in juvenile recruitment and the demographic processes that maintain populations. Furthermore, there is uncertainty in how these processes will be influenced by changing environmental conditions associated with climate change. As such, understanding drivers of recruitment variability was identified as one of the highest research priorities for Snapper at the most recent National Workshop (FRDC Project No. 2019-085; Cartwright et al. 2021). Given the strong relationship between episodic recruitment and fishery production described above for the SG/WCS and GSVS, this recommendation was also strongly endorsed by fishery researchers, managers, and industry stakeholders in SA (Drew et al. 2022).
This research proposal has been developed to address four research priorities: • To understand the biological and environmental factors that affect recruitment of Snapper in SA and evaluate the potential influence of climate change. • Provide a contemporary understanding of stock structure for Snapper on the west coast of Eyre Peninsula to inform the appropriate spatial scale for fishery management. • Develop a contemporary series of biological parameters for each stock of Snapper in SA to be used as inputs in the stock assessment model. • Evaluate changes in the physical environment that may affect Snapper recruitment.
Consequently, Research Theme 1 – Biology and Ecology involves four projects: 1.1 Investigating recruitment variability and evaluating the potential effects of climate change for Snapper in South Australia 1.2 Contemporary demographic processes and stock structure for Snapper on the west coast of Eyre Peninsula 1.3 Review of biological parameters for Snapper in South Australia 1.4 Benthic habitat survey for Gulf St Vincent.
1.1 Investigating recruitment variability and evaluating the potential effects of climate change for Snapper in South Australia The population dynamics and fishery productivity for Snapper in SA are fundamentally driven by highly variable interannual recruitment, i.e., the number of age 0+ juveniles that enter the population each year (Fowler et al. 2017, Fowler and Jennings 2003). As such, a relative index of annual age 0+ juvenile abundance would be a powerful, fishery-independent tool to predict future trends in fishable biomass. To address this need, a recent project was undertaken to identify the most appropriate sampling methodology for age 0+ Snapper in SA’s gulfs and to develop a pre-recruit index (FRDC Project No. 2019-046). The first component of the present study involves the continuation of annual surveys for age 0+ Snapper for each stock to monitor trends in juvenile recruitment. The surveys will be repeated annually at the recognised nursery areas for each stock, i.e., northern Spencer Gulf (NSG) for the SG/WCS and northern Gulf St Vincent (NGSV) for the GSVS (Fowler et al. 2017). In addition, age 1+ juvenile Snapper will be sampled from annual fishery-independent surveys for the Spencer Gulf and Gulf St Vincent prawn fisheries, which will provide further information to determine relative year class strength.
The second component of the study involves investigating the relationships between environmental parameters and recruitment. The datasets for juvenile abundance will be considered with annual population age structures to develop a time series of recruitment for the two stocks (i.e., late 1960s to 2020s). Long-term time series of environmental parameters (e.g., temperature, salinity, productivity, wind stress) will be developed and compared to the time series of recruitment for each stock. In conjunction with the pre-recruit index, understanding the environmental influences that drive recruitment variability would provide even greater predictive capability to forecast trends in recruitment and fishable biomass, particularly under changing environmental conditions associated with climate change.
The third component of the study will investigate the potential effects of environmental change for Snapper in SA. Using the environmental datasets previously developed, a high-resolution oceanographic model for SA will be hindcast to determine the intensity of local environmental change and identify potential climate ‘hot spots’. The model will then be forecast with different climate change scenarios to predict changes in ocean conditions over the next 5, 10, and 50 years. Based on the physiological tolerance ranges for Snapper spawning and larval development, these predictions will be used to evaluate potential shifts in the availability of suitable environmental conditions for Snapper in SA. Such responses will be considered in terms of potential implications for future trends in recruitment and fishable biomass.
1.2 Contemporary demographic processes and stock structure for Snapper on the west coast of Eyre Peninsula There are three recognised stocks of Snapper in SA waters: the SG/WCS, the GSVS, and the Western Victoria Stock (WVS) (Fowler 2016, Fowler et al. 2017). The population of Snapper on the West Coast of Eyre Peninsula (WC) is a regional component of the SG/WCS. It is hypothesised that in most years, the WC population is replenished by local demographic processes that maintain the population at a relatively low level. However, episodically in years of exceptionally strong recruitment in northern Spencer Gulf (i.e., 1991, 1997, and 1999), the WC population is replenished through the density dependent emigration of fish of a few years of age that disperse from northern Spencer Gulf, through southern Spencer Gulf and to the WC. These fish then remain on the WC for the remainder of their lives.
As a consequence of the prolonged period of poor recruitment in northern Spencer Gulf since 1999 and the subsequent depletion of the population in Spencer Gulf, it is unlikely that this density dependent movement from Spencer Gulf to the WC has occurred to a major extent for a number of years or will occur until the Spencer Gulf population has recovered. Furthermore, age structures for the WC developed in 2020 and 2021 showed that only a very small number of fish from the strong 1997- and 1999-year classes in northern Spencer Gulf remained in the population, and there were several other year classes in the age structures for the WC that were not present in northern Spencer Gulf (Drew et al. 2022). Consequently, there is a need to understand the relative contributions of local population processes and emigration from northern Spencer Gulf to the WC population. This is particularly important following the regionalisation of the fishery through the Marine Scalefish Fishery (MSF) Reform (Smart et al. 2022).
This study will investigate the contemporary demographic processes that maintain the population of Snapper on the WC through the regional comparison of population age structures, elemental chemistry of otoliths, and population genomics. The findings will provide insight into the relative contributions of local recruitment and emigration to the WC population, that will be compared to the existing conceptual model of stock structure for Snapper in SA (Fowler 2016, Fowler et al. 2017). The proposed study will build on several previous projects that have investigated the stock structure of Snapper in SA (i.e., FRDC Project No. 2002-001, FRDC Project No. 2012-020, ARC Linkage Project No. LP180100756).
1.3 Review of biological parameters for Snapper in South Australia The biology of Snapper in SA has been studied over the past 40 years, with particular focus on northern Spencer Gulf (e.g., Jones 1981, 1987, McGlennon 2003). Since 2000, a weekly market sampling program has been undertaken by SARDI researchers that has provided biological data for Snapper caught by commercial fishers across SA. The sampling program has been augmented with periodic trips to regional areas, research cruises, and targeted research projects. Since the closure of the SG/WCS and GSVS in November 2019, biological samples from the two stocks have been accessed through a targeted sampling program which involved contracting commercial fishers. The data collected through these projects and programs is maintained in a MS Access database which currently contains biological information (i.e., capture date, location, length, weight, sex, reproductive stage, and age) for >27,000 Snapper and length information for >75,000 individuals.
This study will investigate potential changes in the biological characteristics of Snapper throughout SA over the past 40 years in response to temporal changes in environmental conditions and stock abundance. This will involve spatial and temporal comparisons of length, age, growth rate, and length at maturity for Snapper from each region of SA. The study will also consider various approaches to estimate natural mortality. A key output of the study is a summary of contemporary biological parameters for each stock of Snapper in SA that will be incorporated into the stock assessment model (‘SnapEst’).
1.4 Benthic habitat survey for Gulf St Vincent Snapper utilise a diversity of different benthic habitats throughout its life history, ranging from soft sediments that are favoured by recently settled juveniles to high relief structures that act as aggregation sites for spawning adults. As a result of the significant interannual variation in recruitment observed for Snapper in SA and the subsequent development of a pre-recruit index, there is particular interest in the spatial distribution and relative abundance of benthic habitats that act as nursery areas for age 0+ juvenile Snapper. In order for the pre-recruit index to provide reliable estimates of annual recruitment, it is essential that the key areas which support 0+ Snapper are sampled consistently each year.
In the recent project to develop a pre-recruit index (i.e., FRDC 2019-046), sampling for 0+ juvenile Snapper was targeted at the hypothesised nursery areas for each stock, i.e., northern Spencer Gulf (NSG) for the SG/WCS and northern Gulf St Vincent (NGSV) for the GSVS (Fowler et al. 2017). For NSG, the sampling design was informed by the results of annual surveys in the region from 2000 to 2010, which identified a strong relationship between the spatial distribution and abundance of 0+ Snapper and localised areas of soft, silty benthic substrate (Fowler and Jennings 2003, Fowler et al. 2010). There were no previous surveys for 0+ Snapper in NGSV, and therefore sampling locations were determined by the presence of suitable benthic substrate from existing habitat studies (Shepherd and Sprigg 1976, Tanner 2002). However, from 2021 to 2023, the catches of age 0+ Snapper in NGSV were very low in each annual survey and it cannot be determined if this reflected poor juvenile recruitment in these years, or if key nursery areas were not adequately sampled.
The aim of this study is to quantify the spatial distribution and relative abundance of benthic habitats in GSV, with particular emphasis on localised areas of soft substrate that may support age 0+ juvenile Snapper. The study will use towed underwater video and particle size analysis of sediment samples to quantify habitat types at ~150 sites throughout GSV following the methods recently applied in Spencer Gulf (FRDC 2020-002; Grammer et al. in prep.). The spatial distribution and relative abundance of benthic habitat types identified in this study will be compared to previous surveys in 1964-69 (Shepherd and Sprigg 1976) and 2000-01 (FRDC Project No. 1998-208; Tanner 2002) to assess changes in benthic habitats in GSV over the past 50 years, and how such changes may relate to trends in recruitment and stock abundance for Snapper over this time.
Objectives: 1. Quantify the abundance of age 0+ Snapper in northern Spencer Gulf and Gulf St Vincent to provide relative estimates of recruitment for 2024, 2025, and 2026. Examine the otoliths of these fish to improve the understanding of early life history processes. 2. Evaluate the relationships between environmental parameters and recruitment variability for Snapper in South Australia and evaluate the potential effects of environmental change on spawning and recruitment. 3. Determine the contemporary demographic processes that maintain Snapper populations on the west coast of Eyre Peninsula, i.e., local recruitment vs. emigration from adjacent regional populations, and to use this information to assess stock structure. 4. Assess possible changes in key biological parameters of Snapper for each stock in South Australia in response to temporal changes in environmental conditions and stock abundance. 5. Quantify the spatial distribution and relative abundance of benthic habitats utilised by juvenile Snapper in Gulf St Vincent and assess potential changes over the past 50 years. Read moreRead less
Can Spatial Fishery-dependent Data Be Used To Determine Abalone Stock Status In A Spatially Structured Fishery?
Funder
Fisheries Research and Development Corporation
Funding Amount
$562,128.00
Summary
With the advent of the Status of Australian Fish Stocks (SAFS) process, there is now a requirement to provide a stock ‘status’ determination in addition to the annual TACC determination. The ‘status’ reflects changes in the overall biomass, the fishing mortality, or in their proxies. This has led to disagreements among researchers, managers and industry, largely due to uncertainty around how best to derive a meaningful overall stock status indicator to meet the requirements of the SAFS reporting ....With the advent of the Status of Australian Fish Stocks (SAFS) process, there is now a requirement to provide a stock ‘status’ determination in addition to the annual TACC determination. The ‘status’ reflects changes in the overall biomass, the fishing mortality, or in their proxies. This has led to disagreements among researchers, managers and industry, largely due to uncertainty around how best to derive a meaningful overall stock status indicator to meet the requirements of the SAFS reporting process. These higher-level reporting processes are an important demonstration of sustainable management of Australian fisheries, but only if stock status determinations are accurate and defensible.
Australian abalone fisheries primarily use harvest control rules based around CPUE (Kg/Hr) to set TACC. However, with abalone, stable catch-rates may not indicate stable biomass and/or stable density. Catch-rates are frequently criticised because the effort needed to take a quantity of catch may be influenced by density but also by density independent factors such as conditions at the time of fishing, experience, and the ability of fishers to adjust their fishing strategy to maintain catch rates (diver behaviour driven hyper-stability). While there are many issues with the assumption that CPUE is a reliable proxy for abundance, it is assumed to be so despite the absence of robust data to validate use of CPUE in this way. In some jurisdictions CPUE is supplemented by sparse fishery-dependent size and density data. There is an urgent need to review common assumptions, methods and interpretations of CPUE as a primary indicator, and to determine whether inclusion of spatial fishery data could provide a ‘global’ indicator of stock status for abalone fisheries.
Objectives: 1. Characterise the statistical properties, coherence, interpretability and assumptions of spatial and classic indicators of fishery performance 2. Develop methods for inclusion of fine-scale spatial data in CPUE standardisations 3. Identify methods for detecting hyper-stability in CPUE 4. Determine feasibility of spatial data based stock status determination in spatially structured fisheries Read moreRead less
Biological Parameters For Stock Assessments In South Eastern Australia – An Information And Capacity Uplift
Funder
Fisheries Research and Development Corporation
Funding Amount
$766,806.00
Summary
South-east Australian waters are recognised as ocean warming hotspots and overall, Australian waters have warmed faster than the global average (Hobday and Pecl 2013, IPCC 2019). Key components of the productivity of marine fish (growth, maturity, and recruitment) are expected to be changing in response to shifts in climate and it is entirely possible that there have been changes in fundamental productivity parameters for Australian stocks. The regularity with which the biological parameters ....South-east Australian waters are recognised as ocean warming hotspots and overall, Australian waters have warmed faster than the global average (Hobday and Pecl 2013, IPCC 2019). Key components of the productivity of marine fish (growth, maturity, and recruitment) are expected to be changing in response to shifts in climate and it is entirely possible that there have been changes in fundamental productivity parameters for Australian stocks. The regularity with which the biological parameters that are used in stock assessments are evaluated and updated varies considerably among the species that are targeted in Commonwealth Fisheries. Assessment of changes in these parameters is limited largely to sensitivity analyses consisting of exploring alternate time-invariant values of natural mortality, maturity and stock recruitment steepness at values close to those used in the base-case assessment and generally agreed upon as within acceptable ranges of values. Recently an evaluation of the provenance of the biological parameters used in stock assessments found that species from the SESSF contained the largest number of parameters where provenance could not be ascertained from the literature and that SESSF species comprised over 50% of those species where biological parameters were determined to be more than 20 years old (FRDC project 2019-010, Evans et al. 2022). When plausible changes to biological parameters (such as those that might occur under environmental change) were explored quite substantial changes in biomass estimates for key target species occurs. This means that parameter mis-specification, such as due to relying on older parameter estimates that encode predator-prey and other ecosystem processes from a system state that has since changed, could be a real issue for assessments in the SESSF. The reliance of current assessments on what is likely to be out-of-date information leads to considerable uncertainty, which cannot be easily quantified that then propagates into management decisions. Without an understanding of changes in biological parameters and how these changes might impact assessments, it is difficult (if not impossible) to evaluate whether current management measures are ensuring sustainability. Overall, the project recommended that updating parameters in stock assessments, modifying base cases, or more heavily drawing on results from sensitivity analysis in discussion of stock assessment results would be strongly advisable, especially in regions where large environmental shifts are known to be occurring, such as the SESSF. The RV Investigator voyages to be conducted in 2023 and 2024 under the CSIRO led SEA-MES project provide a unique opportunity to access relevant biological samples that could be used to update the biological parameters identified in FRDC Project 2019-010 as a high priority (age, growth, reproduction, stock structure and although not directly used in stock assessments themselves but having significant influence on parameters that are used in assessments (such as growth and mortality), diet and food webs). These voyages have a focus on the marine ecosystem that supports the SESSF and a number of the hypotheses being posed by the study are focused on target species within the SESSF and their food webs. This will result in significant sampling of those species , with the co-benefit that there will be new samples available for the contemporary estimation of key biological parameters and evaluation of the representativeness of parameters being used in stock assessments (and with sufficient sample numbers to ensure robust updated estimates). These voyages also provide a unique opportunity to build capacity in at sea sampling, exposure to ecosystem level sampling design and post-voyage biological analyses. By linking post voyage analyses with the direct needs of both stock assessments and ecosystem models used in the SESSF, the project provides opportunities for building deeper understanding of the use of biological parameters in stock assessments, and direct application of fisheries biology.
Objectives: 1. Develop, in collaboration and consultation with key research and fishery stakeholders a series of projects involving postgraduate students and early-mid career researchers that directly address priority areas for updating biological parameters for target species in the SESSF and understanding the implications of changing parameters on the fishery 2. Reduce uncertainties in stock assessments for the SESSF through the updating of biological parameters and understanding of key interactions between and drivers of change in biological parameters 3. Progress methods development associated with ascertaining biological parameters and progressing stock assessments to increase efficiencies, reduce time and financial costs, expand applicability and reduce uncertainties in stock assessments 4. Build fisheries capability across multiple pathways to support the ongoing sustainability of high quality fisheries research Read moreRead less
Analysis Of Historical Sea Urchin Research For Improved Management Of Nearshore Fisheries In New South Wales
Funder
Fisheries Research and Development Corporation
Funding Amount
$107,000.00
Summary
The creation, persistence, and demise of sea urchin barrens is the most significant ecological dynamic on southeast Australian rocky reefs. Sea urchin barrens cover ca. 50% of nearshore reefs in NSW and have rapidly grown in Tasmania and far eastern Victoria. The creation and/or persistence of barrens has devastating impacts on a range of commercial and recreational fisheries, most notably abalone.
Managing fisheries to deliver societal benefits within the ecological regime driven by s ....The creation, persistence, and demise of sea urchin barrens is the most significant ecological dynamic on southeast Australian rocky reefs. Sea urchin barrens cover ca. 50% of nearshore reefs in NSW and have rapidly grown in Tasmania and far eastern Victoria. The creation and/or persistence of barrens has devastating impacts on a range of commercial and recreational fisheries, most notably abalone.
Managing fisheries to deliver societal benefits within the ecological regime driven by sea urchins presents a profound challenge. Dynamics external to the fishery are very influential and challenge classical fisheries governance paradigms. Overlayed on these ecological challenges are diverse stakeholders that have different visions for nearshore reefs and therefore the definitions of success.
New management objectives will be required, some of which will mean manipulating ecosystems and human behaviours to avoid thresholds in ecological variables in, among other species, sea urchin abundance, rather than optimizing yields in a classical fisheries sense. New institutional relationships will be required among policy makers, Indigenous groups, conservationists, and the fishing industry as they grapple with potential alternative futures for these reefs.
Considerable momentum is emerging in NSW to engage with this wicked problem. A unique opportunity exists to re-imagine the management of NSW reefs; to design a management regime in which all stakeholders have a place at the table. Fundamental to developing common purpose among diverse stakeholders will be a shared and scientifically informed understanding of the underlying ecology of reefs. This understanding will enable and promote the design for a spatial regime that serves multiple management and cultural objectives.
Achieving that shared understanding is hampered by the unavailability of scientific studies of the fisheries and ecology of sea urchins in southeast Australia. There is an urgent need to bring the comprehensive understanding of the dynamics of Centrostephanus on NSW reefs and relevance to fisheries (abalone, sea urchins) into the public domain to contribute more effectively to management.
Objectives: 1. Analyse historical unpublished data on the ecology of Centrostephanus and its interactions with nearshore biota and augment the findings with oral histories of fishers to inform desirable outcomes for nearshore reef management 2. Submit research findings in the primary scientific literature as five papers and share findings with the primary nearshore reef stakeholders in the form of an accessible synthesis of all research findings. 3. Share findings and conclusions with key stakeholders from NSW, Victoria and Tasmania. Read moreRead less