Barramundi (Lates calcarifer) growth
About Lates calcarifer
L. calcarifer is a long-lived, catadromous fish species that occurs throughout northern Australia. It has been selected as an ecological asset for the Fitzroy WRP because it is a valuable commercial and recreational fishery and has a critical link to flows for the recruitment and growth of juveniles. The development of water infrastructure in the Fitzroy and the associated impacts on connectivity and water quality are known to have impacted Barramundi populations.
This model, describing the flow requirements for Barramundi growth, draws on the work of Halliday and Robins (2007), which used tag-recapture data to determine the relationship between freshwater flows and seasonal Barramundi growth rate. They found substantial benefits to barramundi production from allowing freshwater flows to reach the estuary. This is most likely due to the influx in nutrients reaching the estuary, which has flow-on effects for productivity throughout the trophic chain.
The purpose of the model is to analyses long times series of modelled flow to determine if the risk to Barramundi growth is adversely affected by proposed water resource development for the Fitzroy River (Qld).
This model, describing Barramundi growth is based on an empirical model developed for the Fitzroy River Catchment.
It was developed to support the Queensland Department of Environment and Resource Management’s ecological risk assessment for the Fitzroy River Water Resource Plan (WRP) reviews.
This model and its default parameters were created for application in the Fitzroy River, Queensland.
However, the model parameters could be edited to suit other locations if the underlying observation data exists to create a model of the same form.
Freshwater inflow to the estuary is correlated with Barramundi growth. Growth rate (from Halliday and Robins 2007) is best represented by the equation:
Barramundi Growth (mm/day) = a + b*LN (weekly flow in ML)
Using the constants:
The growth equations varied with season and size class (Halliday and Robins 2007) however, for this assessment, the equation for Barramundi <420mm has been used.
The equation is applied once weekly flow is greater than 1300 ML, since growth rate is constant below this level.
This model produces continuous daily results (Barramundi growth). These results are then aggregated to a binary daily result, then to a binary yearly result, and then further to a binary temporal result based on the defined assessment parameters.
The temporal results are then analysed across locations to report an overall landscape risk by considering the simultaneous occurrence of failures across the system.
- Daily flow data
- Daily temperature data
- Constants (A) – define the values for the a constant in each season
- Constants (B) – define the values for the b constant in each season
- Flow threshold – define the flow threshold that must be met to use the equation for each season
- Daily time series of Barramundi growth rate (mm/day – constant across each week)
- Daily time series of assessment results
- Yearly time series of assessment results
- Temporal time series of assessment results
- Spatial time series of assessment results
This plugin is written in Python and its underlying code is publicly available from the Eco Risk Projector computation repository.
Halliday I and Robins J 2007, ‘Environmental flows for sub-tropical estuaries: understanding the freshwater needs of estuaries for sustainable fisheries production and assessing the Fitzroy Basin Water Resource Plan Review – Technical Report 3: Ecological Risk Assessment 10 impact of water regulation. Final Report FDRC Project No. 2001/022 Coastal Zone Project FH3/AF’, Department of Primary Industries and Fisheries, Queensland Government, Brisbane.