Butlers Creek fish movement studies
Fish movement in response to hydrological management of Butlers Creek at Kings Billabong Nature Reserve, NW Victoria.
October 2013 to June 2014
The Butlers Creek System (BCS) forms part of the Kings Billabong Nature reserve wetland complex. Butlers Creek is a slow flowing anabranch connected to the Lock 11 weir pool of the Murray River at its northern (Baggs Bridge crossing) and southern (Jennings Bridge crossing) effluents. Ducksfoot Lagoon is a small terminal wetland connected to the upstream (southern) end of Butlers Creek, while a smaller Lagoon (Baggs Lagoon) is located at the northern end of Butlers Creek. Assessments of the fish community in the BCS by the MDFRC in 2009 identified nine species of fish including the threatened Freshwater catfish. Off-channel habitats such as Butlers Creek and the associated Ducksfoot Lagoon are important for fish populations because of the increased habitat diversity offered by floodplains, with heightened survival, feeding and reproduction opportunities (Junk et al. 1989; Lyon et al. 2010).
The Mallee Catchment Management Authority (MCMA) has constructed regulators on both the Baggs and Jennings crossings to allow managed control of the systems hydrological regime. Managed environmental watering (particularly wetland filling and draining events) can elicit a range of lateral movement responses (both passive and active) from differing fish species,
The movement responses of fish to managed hydrological events such as wetland filling and draining are however highly variable and poorly understood. The cues for movement could include factors such as flow rates, water chemistry (e.g. dissolved oxygen, salinity, and temperature), scents or nutrient levels in the inflowing water, or biological cues which initiate a behavioral response.
For example repeated assessments of lateral movements at Margooya Lagoon indicated that maturing Golden perch and Silver perch juveniles in the wetland were induced to return to the Murray River (thus contributing to native fish stocks locally) on managed wetland filling events, but not on drainage events (Ellis and Pyke, June 2011). Pest Carp, however, were induced to enter the wetland on drainage events, providing an opportunity for exclusion or stranding of the pest species at aggregation sites.
An MDFRC Acoustic Tracking range finding trial in Kings Billabong recently identified that although acoustic detection using tracking VEMCO VR2W receivers was not suitable in shallower (<1.5m) highly vegetated habitat present over the south-east section of Kings Billabong, they were suitable in deeper sections of the wetland. This indicated that the receivers would potentially be suitable for acoustic tracking of large-bodied fish in other deeper sections of the BCS.
This project aims to utilise the existing MDFRC tracking equipment in assessments of the movement of large-bodied fish in the BCS and other similar wetlands including Kings Billabong during future managed hydrological interventions.
In this clip featured on the MDFRC YouTube channel, Iain Ellis from MDFRC at Mildura talks about techniques available for investigating fish movement in response to changing water levels and flows.