Coastal floodplain management in eastern Australia: barriers to fish and invertebrate recruitment in acid sulphate soil catchments

Funded Activity Summary

Fish habitat in coastal floodplains will continue to degrade unless practical guidelines for improvement of water quality and management of floodgates and other tidal barriers to allow passage of fish and invertebrates are developed. This is being increasingly recognised by many decision making agencies. However, landholders will not change current management practises unless as a minimum, there will be no adverse effects to their productivity. Guidelines for change must be developed in an integrated manner with a focus on land, water, agriculture and fisheries if all industry groups are to accept the changes.

Recent studies by NSW Fisheries (some funded by FRDC) show that a change in coastal floodplain and wetland habitats from freshwater to estuarine and recruitment of fish and invertebrates to these modified habitats can be achieved by increasing the degree of “leakiness” in the floodgate barriers (Gibbs et al. 1997). However, no data are available on the relationship between fish and invertebrate recruitment and the opening size or the frequency and timing of the opening of these floodgate barriers.

A second issue is the long term impact of chronic acid drainage, which does not cause major fish kills but which may have less obvious effects on the recruitment of migratory and catadromous fish such as Australian bass, striped mullet, freshwater herring, eels and school prawns. The life history, behaviour and demography of the catadromous Australian bass shows it is susceptible to such an impact (Harris 1983,1989). The Basscatch program (Harris 1989) has expanded in recent years and the population collapse through recruitment failure of Australian bass in NSW rivers such as the Hastings and Manning is partially attributed to acid drainage (Harris pers comm).

The management of floodgates and floodplains to allow passage of fish and invertebrates and the development of stable faunal communities in previously alienated habitat above the structures significantly enhances fish and invertebrate stocks. The consequent protection of fish habitats and fish and invertebrate species supports biodiversity conservation and the habitat restoration can assist in the development of management plans under the relevant Threatened Species Legislation.

Gibbs, P., McVea, T. and Louden, B. (1997). Utilisation of restored wetlands by fish and invertebrates. FRDC Project 95/150 Final Report (In Preparation).

Harris, J. H. (1983). The Australian bass, Macquaria novemaculeata. Ph. D. Thesis UNSW.

Harris, J. H. (1988). Demography of Australian bass, Macquaria novemaculeata (Perciformes, Percichthyidae), in the Sydney basin. Aust. J. Mar. Freshwater Res. 39: 355-369.

Harris, J. H. (1989). Basscatch - A co-operative fisheries project. Modern Fishing 80-83.

Objectives:
1. To develop guidelines for floodgate / tidal barrier specifications and management based on: (a) The relationship between recruitment of migratory and non-migratory fish and invertebrate species and the opening size of, and the frequency and timing of the opening of tidal barriers. (b) The impacts of changed hydrological conditions on watertable and water flows in associated agricultural land.
2. To assess the behaviour of catadromous fish to the tidal flows through openings in barriers and the behavioural response of recruiting juveniles to low level (chronic) concentrations of acid sulphate soil drainage water.
3. To develop and implement an extension program on the outcomes of the project, and to communicate the above guidelines to agricultural industry groups, local government and other agencies with interests in management of land and water resources in coastal floodplains using demonstration study areas and supporting literature.

Funded Activity Details

Start Date: 30-06-1999

End Date: 01-10-2004

Funding Scheme: Funding Scheme not available

Funding Amount: $601,379.00

Funder: Fisheries Research and Development Corporation

Research Topics

ANZSRC Field of Research (FoR)

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ANZSRC Socio-Economic Objective (SEO)

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Other Keywords

Agriculture | Habitat | Risk reduction | Water quality

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