2025-26 - Year 1 - Colombo Creek Threatened Species Baseline Assessment
Dr John Conallin with a large carp, and Dan Hutton recording the data for the Colombo Creek surveys.
Colombo Creek Fish Survey Highlights Strong Role of Habitat in Native Fish Recovery- 2025-26 Surveys
A new baseline assessment of fish populations in Colombo Creek has confirmed the strong influence of habitat quality on native fish diversity, while highlighting ongoing pressures from invasive carp.
Commencing in December 2025, the three-year program is designed to fill critical knowledge gaps on threatened species, including the endangered Trout cod—one of only two known self-sustaining populations in the Murray–Darling Basin—and the Eel-tailed catfish.
Early survey results from nine locations recorded 1,441 fish across 13 species. Native fish accounted for 39% of all records, while exotic species—dominated by carp—made up 61%, and 81% of total biomass. Carp were found at all sites and were particularly abundant in upstream and mid-reach areas.
Results show a clear pattern across the creek, with higher fish diversity and healthier native populations in downstream areas that have strong aquatic and riparian vegetation. In contrast, mid-reach sections showed reduced diversity and poorer ecological condition.
Water quality remained within acceptable thresholds for fish health across all sites, indicating habitat structure as the key driver of fish community differences.
The survey also recorded 13 freshwater turtles as bycatch, reflecting the broader ecological value of the system.
The report recommends targeted Trout cod surveys near Tarabah Weir, continued monitoring of Eel-tailed catfish, strategic carp control at high-value sites, and restoration of mid-reach habitats. It also supports future consideration of native species reintroductions where conditions are suitable.
The full Colombo Creek Threatened Species Baseline Assessment Report 2025-26 can be accessed in the ‘Report’ section.
Eel-tailed catfish caught and released at Colombo Creek.