Natives and Introduced Fish

Category

How have Australian fish changed over the past few decades?

By Lucy Stuart October 20, 2023

Within the Murray Darling Basin (MDB), experts have estimated a decline in native fish abundance of ~90% since European settlement. Things such as changes to the hydrological regime, habitat degradation, river regulation and infrastructure, over-fishing, and impacts from alien species are all contributing to the ongoing decline (Koehn and Lintermans 2012; Lintermans 2013). Ongoing monitoring

Maccas in the Macquarie River

By Lucy Stuart September 18, 2023

Macquarie perch were once abundant in their namesake, the Macquarie River, yet are now extremely threatened throughout the Murray-Darling Basin.  The species is considered extinct in SA and endangered in NSW, VIC and ACT. Extinction is looming for this little fish, with only four isolated wild populations left in NSW, spanning less than a combined

The plight of Southern Pygmy Perch and the local efforts for recovery

By Lucy Stuart August 31, 2023

Once used as a common bait fish across the Murray-Darling Basin, the now threatened Southern Pygmy Perch (SPP) has now disappeared from most historically known locations. In NSW there are only three broad locations remaining located nearby the towns of Dalton, Holbrook and Albury. The upper Lachlan drainage near Dalton is the most far-north population

Monitoring and managing fishways – what happens after construction?

By Lucy Stuart August 3, 2023

Some time ago, we published an article about the fishways at the Koondrook and Cohuna weirs that were constructed in late 2021. More recently, we pondered on the development of performance standards for fishways and what a good fishway looks like. Although still in development, the researchers at Arthur Rylah Institute (ARI) have been collecting

Redfin perch and the EHN virus

By Joy Becker and Lucy Stuart July 19, 2023

Epizootic haematopoietic necrosis virus (EHNV) is a lethal virus that infects fish through the body surface or gastrointestinal tract. Once in the host, it multiplies in the blood forming organs such as the spleen and kidney and destroys them in the process, ultimately killing the fish. EHNV is only present in Australia, endemic to catchments

Trout and trout stocking: acknowledging the harm, finding the balance

By Lucy Stuart June 26, 2023

A long time ago in a galaxy (not so) far, far away ... aliens infiltrated the ranks of many native fish populations and risked their very survival. Fish may not be an alien concept to us, however, for Australia’s native flora and fauna, alien species pose a real threat. Native fish declines are a big

What have the recent floods meant for the Coorong, Lower Lakes and Murray Mouth?

By Kate McKenna April 5, 2023

Recent floods flowing down the Murray River have well and truly reached the Coorong, Lower Lakes and Mouth of the Murray. All 593 openings across 5 barrages, which for the last 80 years have controlled flows at the Mouth of the Murray, were fully open over the summer, with freshwater, saltwater, fish and other creatures

Floods and fish – how can flooding help fish and aquatic ecosystems?

By Kate McKenna September 28, 2022

Australia’s Murray-Darling Basin, like many other catchments and basins globally, naturally fluctuates between periods of drought and periods of flooding, and has followed this pattern for more than 100 million years. Over time, its many native species have learnt and adapted to this pattern, so that the natural fluctuations between ‘boom and bust’ are now

Protect first, restore second – doing what we can to look after threatened native fish

By Kate McKenna June 30, 2022

Australian rivers are highly modified. In 2003, scientists were already recording that 97% of the rivers in New South Wales were significantly modified, placing immense strain on local aquatic and ecological communities to survive without their natural flow regimes. Almost 20 years on, this is still largely the case for rivers across NSW and the