Setting the trend: Integrating long-term monitoring data to assess trends in riverine fish populations and inform management outcomes across Victoria (#86)
Zeb Tonkin
1
,
Jian Yen
1
,
Adrian Kitchingman
1
,
Frank Amtstaetter
1
,
Graeme Hackett
1
,
Annique Harris
1
,
Wayne Koster
1
,
Jason Lieschke
2
,
Jarod Lyon
1
,
Scott Raymond
1
- Department of Energy, Environment and Climate Action, Arthur Rylah Institute for Environmental Research, Heidelberg, Victoria, Australia
- Department of Energy, Environment and Climate Action, Arthur Rylah Institute for Environmental Research, Heidelberg, Victoria, Australia
- Sustaining or improving native fish populations is a fundamental objective of many waterway management plans and interventions. While restoration projects usually occur over short time periods (1-3 years), changes to fish populations usually exceed this and often occurs at spatial scales beyond the footprint of the intervention. This misalignment through both time and space presents a challenge for managers and scientists, both for legislative requirements of evaluation and in the adaptive management space.
- We integrated more than two decades of fish monitoring data spanning 26 waterways across Victoria to assess long term trends in native fish abundance and recruitment. We used a hierarchical Bayesian model to estimate trends in standardised fish catch through time, while also examining how these trends were influenced by a series of flow and non-flow covariates.
- Broadly, most native fish populations underwent substantial declines until 2010, coinciding with the low flow conditions associated with the Millenium drought. Since this time most species have undergone some recovery, the degree of which varies across species and waterways with some areas subject to major interventions such as environmental water. The modelling approach showed strong predictive power, generating quantitative links between population change and covariates including existing population size, carp abundance, different attributes of the flow regime and temperature.
- We present an evaluation of native fish population dynamics across an expansive spatial and temporal scale, with results directly informing progress towards fundamental objectives embedded in management plans and interventions such as flow management that target native fish population outcomes.
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