Common problems include sections of creek that are only accessible at high tide or during flood events. Unlike the well-known Atlantic Salmon, native fish don’t possess the ability to ‘leap’ during upstream migrations; small native fish can manage a jump of 70mm. Another issue is that water flow may be too strong; for instance, smaller fish can only swim against a water velocity of 0.3-0.5 m/sec. Native fish, particularly small bodied and juvenile fish, are quite poor swimmers, only able to travel fast (burst speed) through high velocity water for short distances, before having to rest and regain their energy (Fishing World 20/9/2017)., Along with colleagues Jack McCann & Trent Power, Matt completed a major study of fish barriers in the Greater Brisbane area in 2018, using GIS to analyse 13,629 potential fish barriers and prioritise them for remediation. In our catchment, the ‘apron’ drop at the Logan Rd bridge on Norman Creek ranked as number 20, and the long stretch of concrete channel in Greenslopes/Stones Corner ranked as number 40.
The main mitigation strategy highlighted by Matt was the use of rock ramps. These involve carefully placing large rocks to form a ramp comprising many small drops and incorporating resting pools. With reduced water velocity and sufficient resting areas fish can more easily access upstream. One of Matt’s more recent rock ramp projects took place at Slacks Creek near Paradise Road. The ramp and associated culvert baffles have allowed increased movement up to 1384 fish per day, 98.9% of which are native species.
To benefit fish trying to swim up a long continuous gradient such as a concrete channel, Matt’s report recommended horizontal culvert baffles. These are small concrete bars across part of the stream, and would provide a sufficient resting area to allow small fish to swim further up the stream. In the absence of this, another more informal strategy could be used: a small chunk of wood or a rock resting against the edge of the channel every so often along the channel. In fact, the Hanlon Park rejuvenation project will be removing the concrete channel problem from Cornwall St down, but upstream of that, the difficulty will remain along the long concrete section until Ridge St.
Matt’s fish barrier prioritisation report is an excellent tool for planning works in waterways, whether it be a new creek crossing or a creek restoration project. His designs for rock ramps are very successful and have been adopted by several local governments in the southeast. Designing our waterways to assist fish movement improves the overall resilience and ecological health of the catchment. This also supports the local community by creating waterways which are full of life. We hope that it will be possible to have the fish barriers in our catchment effectively remediated.
We thank Matt for kindly sharing his knowledge and expertise with us.
Catchment Solutions. (2018). Greater Brisbane Fish Barrier Prioritisation. http://catchmentsolutions.com.au/files/2018/05/Greater-Brisbane-Fish-Barrier-Prioritisation-Report.pdf
Fishing World. (2017). Slacks Creek rock ramp and fishway. Retrieved 15/3/2019 from http://www.fishingworld.com.au/news/slacks-creek-rock-ramp-and-fishway#VHVVfQRuZBoWrxzV.99
