Threatened native fish finding homes in town lakes

SMALL FARMS -  MAY 2022 - NATIVE PLANTS & ANIMALS

By Josh Campbell
Land Services Officer - Environment
P: 03 5881 9935 | M: 0427 104 874 | E: josh.campbell@lls.nsw.gov.au

Investigations are underway to expand the Threatened Native Fish Recovery Program across the Murray Region.

The Program aims to prevent the extinction of, and promote the recovery and persistence of, threatened floodplain specialist native fish, by improving habitat at surrogate breeding sites. The aim is to rebuild populations of threatened Southern Pygmy Perch and Southern Purple Spotted Gudgeon for future release into the wild.

Numbers of various small-bodied and wetland specialist native fish have decreased across the Murray Darling Basin due to habitat loss, invasive species, river regulation and drought. In fact, populations of some species are so low that there are only very small populations left in the wild and/or surrogate breeding sites. At the moment we simply don’t have the numbers of these species to release back into the wild.

However, many towns in our region have lakes for activities such as water storage or stormwater management. These lakes can be a great asset to our towns, offering areas for recreation activities like water skiing, fishing, walking, birdwatching and just enjoying nature. They also provide opportunities for tourists to stop and stretch their legs and perhaps look around town or stay in caravan parks bordering some lake areas. But these town lakes can also be great surrogate breeding sites!

In 2010 an initiative was started to restore the Deniliquin town lagoons system to be able to re-establish threatened wetland specialist fish species and act as an outdoor threatened species centre. To date, four lagoons have been restored and two have the threatened Eel-Tailed Catfish and Southern Pygmy Perch breeding in them. Southern Purple Spotted Gudgeon’s have also recently been released into the lagoon system.

Following the success of the Deniliquin lagoons project, Murray Local Land Services has undertaken habitat and fish community assessments at lakes in Finley, Moulamein, Barham, and Jerilderie to see if they are suitable to act as surrogate breeding sites.

Eel-Tailed Catfish, which are close to extinct in the local river system, already call all four lakes home. Catfish were stocked into Barham Lakes around 20 years ago and have since bred and a healthy self-sustaining population lives in the lake. Over the past few years, Catfish have been translocated from Barham to Moulamein Lake and the Deniliquin lagoon system where they have bred successfully and recently from the Deniliquin lagoons to Finley and Jerilderie lakes, demonstrating how having a network of surrogate sites can help in the recovery of these threatened fish.

To be successful, surrogate sites need land manager and community support, a secure water source, good vegetation, woody debris and a lack of exotic species such as carp, redfin and Gambusia.

The monitoring showed the lakes are all in good condition with good water quality and established vegetation, which is not surprising since most have hard-working community groups working alongside local councils to keep the sites healthy and looking great. One concern is all lakes currently have exotic species, such as carp and gambusia. However, managing invasive pest fish species can be made easier by having complex and varied habitats within a wetland, so that species are not forced to interact.

The next step for the project is revegetation works and placement of large woody debris at one of the lakes to improve habitat for the future release of Southern Pygmy Perch in the hope that they breed, continuing to build numbers for potential releases into the wild in the future.