Oral Presentation Australian Society for Fish Biology Conference 2017

Quantifying links between instream woody habitat and riverine fish populations (#45)

Zeb Tonkin 1 , Adrian Kitchingman 1 , Jarod Lyon 1 , Renae Ayres 1 , Joanne Kearns 1 , Ben Fanson 1
  1. Arthur Rylah Institute, Department of Environment, Land, Water and Planning, Heidelberg, VIC, Australia

Victoria’s instream habitats are highly valued, broadly, because of their contribution to catchment health, biodiversity and supporting self-sustaining fish populations. There is increasing interest and investment in managing instream habitat, particularly improving instream woody habitat (IWH) because there have been major reductions of IWH in Victorian rivers. Such changes are a major contributing factor to declines in riverine productivity and diversity of aquatic ecosystems, including native fish. With a priority objective of many IWH programs being an increased abundance and diversity of fish populations, waterway managers require specific guidance on IWH restoration approaches to maximise benefits to a region’s fish community for a given investment.

The vast majority of previous research demonstrates the links between IWH and riverine fish distribution and abundance at micro- and mesohabitat scales. Its role in governing species diversity and distribution across reach and basin scales has received far less attention, particularly within Australia. As such, we investigated the links between instream habitat parameters and fish populations at sub-reach scales in nine waterways across Victoria. This paper presents quantitative predictions of reach-scale responses in abundance and biomass by various fish species to changes in these habitat parameters (particularly IWH) in a variety of river types frequently targeted for intervention works across Victoria. Results are discussed in relation to habitat degradation and existing restoration programs across Victoria.