Plenary Presentation Australian Society for Fish Biology Conference 2022

ECR Excellence Award Plenary (2020) - Linking processes to populations to understand the drivers and dynamics of freshwater fish populations in south-eastern Australia (#4)

Zeb Tonkin 1 , Jarod Lyon 1 , Wayne Koster 1 , Justin O'Connor 1 , Ivor Stuart 1 2 , Charles Todd 1 , Jian Yen 1
  1. Arthur Rylah Institute, Department of Environment, Land, Water and Planning, Heidelberg, VIC, Australia
  2. Gulbali Institute, Charles Sturt University, Albury, NSW, Australia

The magnitude and rate at which fish populations change is determined by key population processes related to recruitment, mortality and migration. To understand the population dynamics of species, scientists and managers require knowledge of how these processes are influenced by key intrinsic (e.g. growth, spawning, survival, genetic structure, competition and predation) and extrinsic factors (e.g. rainfall, temperature and connectivity). Globally, fisheries science literature has many examples of that relate the drivers of key processes to the dynamics of fish populations. This is particularly relevant for species supporting large commercial fisheries (especially marine). Freshwater fishes however, have far fewer examples which adhere to these principles. For many Australian freshwater fish species, knowledge is often limited to specific aspects of biology or a specific process, with studies which take a holistic approach in considering potential population drivers being rare. This limits our ability to effectively manage fish populations or develop strategies that optimise the ecological benefits of rehabilitation activities such as environmental flow delivery, habitat restoration, or fish stocking. Moreover, a lack of links between process specific research and population dynamics can also lead to doubt by managers and stakeholder groups on the relevance of the research we do. In recent years, researchers have increasingly addressed such shortfalls, culminating in several large monitoring and research programs that capture multiple data types and evaluation approaches. Importantly, these programs have fostered strong collaborations between individual researchers, agencies and waterway managers. This talk presents a variety of examples that draw links from specific investigations of processes and intrinsic factors to the dynamics of populations for several freshwater fish species across south-eastern Australia. Our examples demonstrate how this whole of life-cycle framework is being used by managers to enhance populations of important species such as Murray cod, Macquarie perch and Silver perch.