Macquarie perch

Macquarie perch that exist in the Cotter River migrate upstream out of Cotter Reservoir in spring, to spawn in the cobble-bottomed riffles of the Cotter River. This habitat is essential successful reproduction, and loss of this habitat due to infilling of interstitial spaces with sediment or restricted access to the habitat due to flow modification or barriers to passage are a real threat to the persistence of the population. With the construction of the enlarge Cotter Dam looming, we aimed to investigate the swimming abilities of the Macquarie perch, and whether we could identify any obstacles to their annual upstream migration.

I conducted this research as part of my Honours degree, and published it in 2011 in Fisheries Management and Ecology. See link at bottom of the page.

Swimming trials
Macquarie perch were collected from Cotter Reservoir and maintained in aquaria at the Australian National University, in 2008/2009. I conducted a series of swimming trials on these fish, to quantify their prolonged swimming ability (Ucrit) and their sprint swimming ability (Usprint). Trials were conducted at three temperatures (10, 16 and 22 degrees) to explore the impacts of water temperature on their swimming performance. I found that larger fish have greater swimming performance than smaller fish, and were more resilient to lower water temperatures.

Flow profiling
To relate Macquarie perch swimming performance to instream obstacles, I conducted a series of flow profiling surveys on potential obstacles in the Cotter River. I examined the effective fishway at Vanitys crossing, and the potential barrier, Pipeline Road crossing. I measured water velocity within these structures on a range of low and high river discharges. Finally, I developed a model that related fish swimming performance to instream water velocity to predict likely fish passage under a range of flow and temperature regimes. This model highlighted that Pipeline Road crossing may be a significant impediment to upstream migration for Macquarie perch. A fishway has since been built at this structure.
Picture
Probability of successful passage in relation to Macquarie perch total length, through Vanitys crossing fishway under low flow (left) and high flow (right) conditions and temperature regimes.
Starrs, D., Ebner, B.C., Lintermans, M., and C.J. Fulton (2011) Using sprint swimming performance to predict upstream migration of the endangered Macquarie perch in a highly regulated river Fisheries Management and Ecology 18: 360-374 doi: 10.1111/j.1365-2400.2011.00788.x LINK