Relationships Between Fish Faunas And Habitat Type In South-western Australian Estuaries
Funder
Fisheries Research and Development Corporation
Funding Amount
$480,277.84
Summary
Since estuaries constitute such an important environment for many recreational and commercial fish species, plans for their management must be based on reliable data if they are to be useful in protecting and, if necessary, restoring crucial estuarine fish habitats. Managers thus require the following. 1. Sound quantitative data on the ways in which commercially and recreationally-important fish species and their different life cycle stages are distributed among the different types of habita ....Since estuaries constitute such an important environment for many recreational and commercial fish species, plans for their management must be based on reliable data if they are to be useful in protecting and, if necessary, restoring crucial estuarine fish habitats. Managers thus require the following. 1. Sound quantitative data on the ways in which commercially and recreationally-important fish species and their different life cycle stages are distributed among the different types of habitat found in south-western Australian estuaries. 2. An ability to identify rapidly and reliably the type of habitat to which any site in an estuary should be allocated and therefore also to predict the likely composition of the fish fauna at that site. 3. Knowledge of the extent and distribution of the various habitat types within and amongst different estuaries which can serve as benchmarks against which the impacts of future environmental changes on the fish faunas can be gauged. 4. An understanding of the relationships between the benthic invertebrate components of the fauna, particularly those that make major contributions to the diets of fish, and the different types of habitat in estuaries. This will facilitate an assessment of the broader implications of changes in the estuarine environment on the fauna as a whole.
This project is necessary to underpin the following conservation planning and programmes. Western Australian Marine Conservation Reserve Program under the CALM Act (1984), the Comprehensive Management Plan (parts c, d) in the Environmental Protection Policy for Swan and Canning Rivers (Government Western Australia 2003), the Peel Development Commission in sustaining environmental health of the Peel-Harvey Estuary, the Recfishwest Policy detailing their Guiding Principles for Responding to Coastal, Marine, Riverine and Impoundment Development Proposals, and the Fish and Fish Habitat Protection Program undertaken by the Department of Fisheries WA. . . Objectives: 1. Determine the suite of environmental criteria that are most useful for readily and quantitatively assigning any site in a particular estuary in south-western Australia to its appropriate habitat type. 2. Determine statistically how the compositions of the fish and benthic invertebrate assemblages in particular south-western Australian estuaries are related to habitat type. 3. Formulate a readily usable and reliable method for predicting which fish species are likely to be abundant at any particular site in an estuary. Read moreRead less
Objectives: 1. To identify whether the effects of estuary hauling over seagrass meadows is identifiable at the estuary level. 2. To assess the 'within-estuary' impacts of hauling, if any, on seagrass frond height, density and cover. 3. To interpret the results in relation to known information on the utilisation of the seagrass habitat by fish.
Objectives: 1. Examine status of Clarence River finfish fishery; assess impact of Red Spot on the commercial fishery 2. Identify possible causes of red spot disease
Functional links between estuaries and their catchments: How does land use change affect estuarine ecological and bio-geochemical function? Estuaries are iconic recreational areas of high ecological and socio-economic value. Estuarine health is strongly linked to the catchments that feed them, yet we have no detailed understanding of these links. This project will use a number of state of the art approaches to better understand how land use affects estuarine health.
Objectives: 1. To extend an ongoing study to make the work relevant to the general coastline of eastern Australia 2. To identify key degraded wetlands on the NSW coast that have the potential to be rehabilitated
New tools to detect ecological effects of contaminants in estuaries. Identifying risks to estuarine environments from pollutants is difficult for environmental managers, who must choose between laboratory toxicity testing that is precise, but hard to generalise to field situations, and more realistic field-based monitoring, which is expensive, with a high signal to noise ratio. New molecular techniques may provide more options. Metabolomics can provide insights into the health of animals, and ec ....New tools to detect ecological effects of contaminants in estuaries. Identifying risks to estuarine environments from pollutants is difficult for environmental managers, who must choose between laboratory toxicity testing that is precise, but hard to generalise to field situations, and more realistic field-based monitoring, which is expensive, with a high signal to noise ratio. New molecular techniques may provide more options. Metabolomics can provide insights into the health of animals, and ecogenomics offers a way to rapidly assess the composition of an ecological community. These techniques offer great promise, but they must be cross-validated against existing methods to derive the best ’toolbox’. Working with Melbourne Water and CSIRO the investigators aim to do this using demonstration estuaries in Victoria.Read moreRead less
Physical Effects Of Hauling On Seagrass Beds (stage 2) (an Extension To 95/149)
Funder
Fisheries Research and Development Corporation
Funding Amount
$44,992.34
Summary
In discussions with estuarine hauling crews, it is clear that they avoid landing their nets in areas of dense seagrass. This potentially confounds the results obtained in the survey of the 9 estuaries. Given that we must sample sites where hauling occurs and hence where the nets are landed (logically), there can be at least two ways of interpreting consistent differences in shoot density and/or leaf-lengths between the control and hauled sites. First, the results provide some evidence that ha ....In discussions with estuarine hauling crews, it is clear that they avoid landing their nets in areas of dense seagrass. This potentially confounds the results obtained in the survey of the 9 estuaries. Given that we must sample sites where hauling occurs and hence where the nets are landed (logically), there can be at least two ways of interpreting consistent differences in shoot density and/or leaf-lengths between the control and hauled sites. First, the results provide some evidence that hauling has an impact on seagrass beds. Second, that the results simply reflect industry's choice to land their nets in areas of reduced amounts of seagrass and hence hauling has little or no impact. Clearly, if this project is to make some recommendations regarding the impacts of hauling and hence its management, we should, if at all possible, avoid concluding the research with these 2 alternatives at the centre of debate.
This seemingly intractable situation is not as hopeless as it would first appear. Previous research (e.g. Larkum et al., 1984) has shown that Zostera capricorni undergoes a cycle of growth in the spring and summer months followed by a dieback in the autumn and winter months. Given that the sampling for the survey has already been completed i.e. well prior to the seagrass attaining maximal shoot densities and leaf-lengths, it would be possible to take advantage of this period of enhanced growth to overcome the shortfalls discussed above. To do so would require that the the same sites be sampled again in late summer because if hauling was having an effect on shoot density and/or leaf-length it would be more clearly evident at this time of year. Furthermore, as we would have a baseline dataset we would predict that the change in shoot density and/or leaf-length from time 1 to time 2 would differ at the hauled compared to the control sites This would occur because the growth of the seagrass would be unaffected at the control sites where it would reach maximal shoot densities and leaf-lengths compared to the hauled site where it would not.
Clearly, the additional sampling described above would require an extension of the project beyond its current completion date in December, 1996. It is envisaged that a further 6 months would be required to complete the additional work necessary. It is important to note that this increased cost of identifying the potential impacts of hauling on seagrass will better serve the fishing industry as the greater scientific rigor gained will reduce the likelihood that the industry is blamed for changes that are not of its own making. Moreover, this approach would likely be the most cost-effective solution to overcome the potentially confounded result that will stem from the existing sampling. A far more costly solution would be to carry out a large-scale field experiment over a number of years to provide 'Before' and 'After" data for hauled and control sites. Objectives: 1. To identify whether the effects of estuary hauling on seagrass meadows is identifiable at the estuary level. 2. To assess the 'within-estuary' impacts of hauling, if any, on seagrass frond height, density and cover. 3. To interpret the results in relation to known information on the utilisation of the seagrass habitat by fish. Read moreRead less
Modelling Multi Species Targeting Of Fishing Effort In The Queensland Coral Reef Finfish Fishery
Funder
Fisheries Research and Development Corporation
Funding Amount
$369,128.00
Summary
The Coral Reef Fin Fish Fishery (CRFF) is a multi-species line fishery. Until recently there have been substantial gaps in our knowledge of the biology of even the major target species of the line fishery and considerable uncertainty about the impacts of current levels of fishing on the harvested stocks.
The CRC Reef Effects of Line Fishing (ELF) Project has provided an improved understanding of: i) the biology of the major target (coral trout and the red throat emperor) and by-product ....The Coral Reef Fin Fish Fishery (CRFF) is a multi-species line fishery. Until recently there have been substantial gaps in our knowledge of the biology of even the major target species of the line fishery and considerable uncertainty about the impacts of current levels of fishing on the harvested stocks.
The CRC Reef Effects of Line Fishing (ELF) Project has provided an improved understanding of: i) the biology of the major target (coral trout and the red throat emperor) and by-product species (stripey bass, moari wrasse, barramundi cod, lesser serranid spp, etc) and, ii) the characteristics and fishing practices of the different sectors of the fishery. One of the main tools for delivery of the outcomes of the ELF Project is ELFSIM, a set of simulation models that will be used to evaluate alternative management strategies against specific objectives for common coral trout.
Given the multi-species nature of the CRFFF, there is a need to address the implications for the effectiveness of alternative management strategies of fishers harvesting different species, with divergent distributions and biology, either by targeting or as a significant by-product when targeting other species. This is especially relevant on GBR where many species have different spatial distributions and area closures are a prominent management strategy that directly affects the distribution of fishing effort. An example of a potential management strategy that includes criteria for which coral trout and red throat emperor differ substantially is the proposed spawning closures currently being considered by REEFMAC. The proposed closures target the peak spawning period for common coral trout (October-November). This period does not, however, include the majority of the spawning season for red throat emperor (July-September). The potential effects of the closures, if implemented, on the harvest of either species, the spatial distribution of effort and impact on the fish stocks are unknown. The models proposed in this task will provide a formal context in which to examine the range of potential responses.
Previously our capacity to address the multi-species nature of the fishery was limited by a paucity of information (for target species and fishing practices) and lack of a formal framework (management strategy evaluation (MSE)) to do so. This project is a strategic requirement to explicitly incorporate the multi-species nature of the CRFF in the evaluation of alternative management strategies for line fishing on the GBR. While this project focusses on the CRFF, the tools developed will provide the basis for extension to include other species of the line fishery or application to other fisheries. This project directly addresses QFIRAC objectives 1.8, 3.2, 3.4, 3.5 & 5.4 and ReefMAC’s and GBRMPA's concern for management of the diversity of impacts of the line fishery on species other than coral trout. Objectives: 1. Document the decision-making processes that influence effort distribtuion of GBR line fishers in response to varying amounts of catch of target and non-target species and characterise the factors that result in changes in targeting behaviour by GBR line fishers. 2. Develop computer simulation models that predict the spatial distribution of effort by commercial line fishers in response to changing levels of catch of target and non-target species in the Queensland Coral Reef Fin Fish Fishery. 3. Formally evaluate alternative harvest and conservation management strategies for coral trout and red throat emperor for the Queensland Coral Reef Fin Fish Fishery, given models of changes in fishing strategy related to the harvest of multiple species, either through target switching or retention of significant by-product. Read moreRead less
Testing the waters: impacts of contaminants on ecosystem structure and function in urban waterways. To ensure that people can swim, catch fish and enjoy the beauty of urban waterways we need to be able to predict the effects of more than one stressor at a time. This project will determine how nutrients and metals affect our waterways. Findings will help prioritise management actions that protect biodiversity and human uses of these systems.