Breeding and Releasing Edelia vittata
the native Western Pygmy Perch

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Introduction ...

Waterways and natural wetland ecosystems around the world are under threat from the activities of man. This is resulting in a huge decline in biodiversity, with many aquatic species becoming extinct or threatened.

The SW corner of Western Australia is no exception to the impact of manís activities. There is a rapid decline in the area of wetlands, increase in salinity in some regions, an increase in weeds, and introduced predators such as fish species like the gambusia, Gambusia holbrooki and redfin perch, Perca fluviatilis, all to the detriment of the natural aquatic ecosystem. Only ten unique native freshwater fish species inhabit the waterways of the SW area.

Many†are threatened and numbers are in decline (Morgan and Gill 1998.).  The western pygmy perch, endemic to this area, are disappearing from large areas of their previous range as man reclaims and interferes with its natural habitat. Our investigations in 1999 in the Five Mile Brook and the associated wetlands found very little evidence of the western pygmy perch in the waterways around Bunbury. Instead these areas were densely populated with the introduced fish, gambusia (Gambusia holbrooki), introduced to Western Australia in 1934.

The native western pygmy perch (Edelia vittata) is a valuable part of the SW freshwater ecosystem. It controls human pests such as mosquitoes and midges by feeding on their larvae, is a valuable food source for many animals, of mutual benefit to marron, Cherax tenuimanus as it feeds on parasites (temnocephlids) growing on the marron . The western pygmy perch is an excellent aquarium fish and suitable for aquaculture in marron farms.

A major objective from our 2000 Management Plan for our school wetlands was to rehabilitate the area and restock our wetlands with native western pygmy perch.

Before we began our breeding program we identified the conditions of the western pygmy perchís natural habitat This included collecting data from waterways where the western pygmy perch was known to inhabit. We also familiarized ourselves with the biology of western pygmy perch.†

We are concerned that the western pygmy perch is no longer common in our district and decided to rectify their population decline. The problem of producing suitable numbers to restock natural waterways could be solved by establishing a year round breeding program. The rearing of egg laying fish can be hampered by predatory adults so we needed to find suitable methods of separating the eggs and juveniles from the adults.†

If we can establish a breeding population, how do we know whether the habitat where they are to be released is suitable? We have to ensure that the fishes habitat is rehabilitated to a satisfactory level before they are reintroduced back into their natural environment.

Therefore the aims of this research are to

  1. Develop a captive breeding program for a native fish species, the western pygmy perch.

  2. Develop rehabilitation techniques to improve the water quality and the natural habitat of the fish so that they can be safely released into the wild.

The relevance of our research is that our methods and innovations we have developed can be repeated and applied to other fish and their waterways under threat around the world. Improving aquatic ecosystems will benefit mankind by improving the quality of water, biodiversity of life in the water and so quality of our life.

 

by Vanessa Hollis, Sandi Roukens and Andrew Shaw