Why? The Mitta Mitta River downstream of Lake Dartmouth suffers from all the typical “tailrace” river issues (eg reversed seasonal flow cycles, cold water pollution). It was considered that the likelihood of maintaining a viable population of Murray Cod (Maccullochella peelii) under these conditions was unachievable. However persistent reports from recreational fishers suggested that the Cod population was stronger than expected.
Working with the Murray Darling Basin Authority (MDBA), local community and the Arthur Rylah Institute (ARI) a works and monitoring program was developed. Investment via the Recreational Fishing Licence Trust was secured to fund the investment in Instream Woody Habitat (IWH) installations, with co-contribution from the MDBA.
What? Over 500 pieces of IWH were sourced and incorporated into MDBA Channel Capacity works over 6 years, with post works monitoring (electro fishing & Otolith micro chemistry) carried out by the ARI.
What have you learned?
Murray Cod were found to be abundant within the lower Mitta Mitta River and are in peak physical condition.
It was proven that IWH can be successfully incorporated into traditional structural work interventions.
Recruitment remains a major issue, however immigration of fish from downstream reaches appears to be sufficient to maintain a strong, mixed age-class fishery.
Why does it matter?
There are three key findings: