Increased numbers of Murray Cod and Golden Perch and declines in introduced Redfin Perch compared to 20 years ago, are just two of the findings of a recently completed study of fish populations in the lower Goulburn River.
Increased numbers of Murray Cod and Golden Perch and declines in introduced Redfin Perch compared to 20 years ago, are just two of the findings of a recently completed study of fish populations in the lower Goulburn River.
The report, Status of Fish Populations in the Lower Goulburn River (2003-2012), was prepared by the Arthur Rylah Institute for Environment Research for the Goulburn Broken Catchment Management Authority (CMA) and documents the findings of a nine-year study of fish populations in the Goulburn River from the Goulburn Weir near Nagambie to the Murray.
Some of the key findings of the study included:
• Significant populations of native fish occur in the lower Goulburn River, including several species of conservation significance, namely Trout Cod (Maccullochella macquariensis), Murray Cod (Maccullochella peelii), Silver Perch (Bidyanus bidyanus) and Freshwater Catfish (Tandanus tandanus).
• There is evidence of increased numbers of Murray Cod and Golden Perch and declines in introduced Redfin Perch (Perca fluviatilis) in recent years compared to the 1980s.
• Despite being previously abundant, Macquarie Perch (Macquaria australasica) now appears to be locally extinct in the main channel of the lower Goulburn River. However, a number of populations exist in other parts of the Goulburn Broken catchment.
• A number of key species are breeding in the Goulburn River, including Freshwater Catfish, Trout Cod and Silver Perch.
• Golden Perch and spawning of this species appears to be associated with increases in discharge, particularly large flows/floods. Murray Cod spawning occurred annually in the lower Goulburn River regardless of river discharge.
• Key threats to the native fish include drought, floods, blackwater, loss of habitat via removal of woody debris, reductions in water quality and the spread of introduced pest fish species.
• Carp populations remained relatively stable during the drought (1997 to 2009), however, following widespread flooding in 2010, Carp from other waterways were washed into the Goulburn resulting in a considerable increase in the size of the population.
Goulburn Broken CMA River Health Implementation Manager Mark Turner said the project revealed important information about links between flow factors and fish spawning, recruitment and movement.
“This information can now be used during the development of Annual Watering Plans and requests for delivery of environmental flows within the lower Goulburn River,” Mr Turner said.
The study was funded under the Victorian Recreational Fishing Grants program from 2003 to 2006 through the Goulburn Valley Association of Angling Clubs and more recently by the Goulburn-Broken CMA (2006 to 2012).