The southern-most recording in Australia of a small and elusive native fish species was among the highlights of the 2022 Murray–Darling Basin Fish Survey (MDBFS).
Since 2014, the native fish survey has been collecting vital data about native fish across the Basin including the number of species present, the distribution of those species, their condition, and their abundance and recruitment.
The 2022 survey sampled more than 11,000 individual fish from 32 species, including 23 native species and 9 ‘alien’ species.
Standard sampling methods such as bait traps and electrofishing (a common and non-harmful technique using direct current electricity to attract fish) were used at 106 sites across the Basin for the 2022 survey.
The survey results show positive signs for some of the Basin’s important native fish species.
Golden perch were in high abundance and showed good recruitment. In weighted terms, the number of golden perch sampled was double the annual average. The Condamine, Warrego and Darling valleys contained almost three-quarters of the golden perch sampled, with the survey identifying mass recruitment in response to the good flows experienced during the past 3 years.
Murray cod showed some recovery from the drought conditions of 2017-19, particularly in the southern Basin, but have since been impacted in some areas by blackwater. Murray cod in the northern Basin also showed recovery, but only in some valleys. Recovery in the Border Rivers was slower than expected.
Large floods like those experienced in 2022 can impact Murray cod recruitment in both positive and negative ways. High velocity flows can flush eggs and larva from nests before the fish have sufficiently developed to feed and survive, leading to fewer ‘baby’ cod in the system. On the flip side, higher flows also inundate more habitat and generate more food resources for growing fish, increasing their chance of survival.
Floods also impact adult Murray cod in a variety of ways. The recent large-scale blackwater events led to many large cod being lost from the system. However, higher flows also provide opportunities for fish to move into the areas impacted by droughts and large-scale fish deaths, kick-starting the slow process of recovery in those areas.
That is why tracking Murray cod recovery requires long-term monitoring and data, and a patient approach to management decisions.
Among other results, the 2022 survey also found the southern-most record of Rendahl’s tandan in Australia – captured in the Narran River in New South Wales. This small and elusive catfish is associated with aquatic vegetation, and previously had only been recorded on a few occasions in the Basin in tributaries of the Condamine River.
Monitoring environmental conditions and the health of animal and plant species across the Basin – including the annual native Fish Survey – are important activities for the Murray–Darling Basin Authority.
Water management decisions and the successful delivery of the Basin Plan rely heavily on the results and findings of monitoring programs. The results also provide valuable input into work such as the 2025 Basin Plan Evaluation and the 2026 Basin Plan Review.
Data collected from the survey is publicly available at data.gov.au
Contact the MDBA media office at media@mdba.gov.au or 02 6279 0141