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.
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