Poster Presentation Australian Society for Fish Biology Conference 2022

Cone Fishways, the development of fishway hydraulics through in-fishway fish movement behaviour. (#216)

Tim Marsden 1
  1. AFPS, Fern Bay, NSW, Australia

Cone fishway are a relatively new version of a pool and weir fishway developed in Australia to facilitate the passage of a broad range of migratory species and life stages, particularly small and juvenile fish (<300 mm long). Despite having a relatively narrow headwater operating range, the cone design has been favoured in a number of locations for its fixed minimum headwater level, compact footprint, high discharge at rising headwater levels and success at passing very small fish (i.e. 15 mm long). Cone fishways have commenced rolling out in all eastern Australian states as well as in Laos, Cambodia and Thailand. The cone design has been very successful and is now recognised as a viable alternative at structures up to 4 m high. The success of the cone design centres around the internal flow dynamics of the cone ridges and pools. The faceted cone shape creates short high velocity transition zones with close fish approach positions; the pools also provide improved hydraulic conditions for small fish. Recent Computational Fluid Dynamic (CFD) modelling of a number of cone fishways has visually highlighted these hydraulic benefits. Both field trials and CFD, highlight the complex interaction of water velocity and turbulence that govern fish ascent pathways and success when navigating fishways. We present results from both fieldwork and CFD to demonstrate how fish behaviour and movement drove the initial cone concept and discuss further design improvements to support fish migration and population recovery.