Oral Presentation International Conference on River Connectivity (Fish Passage 2018)

Fish passage hydrodynamics New Zealand context     (#18)

Morten MK Knapp 1 , John JM Montgomery 2 , Colin CW Whittaker 1 , Paul PF Franklin 3 , Cindy CB Baker 3 , Heide HF Friedrich 1
  1. Civil and Environmental Engineering, University of Auckland, Auckland City, Auckland, New Zealand
  2. Institute of Marine Science, University of Auckland, Auckland City, Auckland, New Zealand
  3. Freshwater Ecology, National Institute of Water & Atmospheric Research, Hamilton, Waikato, New Zealand

New Zealand is home to 57 native freshwater fish species, of which a considerable number are diadromous, having to move between freshwater and saltwater at least once during their lifecycle. The economic utilisation of New Zealand rivers has largely been carried out without fish migration behaviour in mind, resulting in thousands of structures that prevent fish migration up- and downriver. Remediation of existing structures, especially culverts, and construction of new, more fish friendly, structures requires in-depth knowledge of the needs of the target fish species. In April 2018, the New Zealand Fish Passage Guidelines were released, providing a design framework to enable fish passage in new and existing structures. In support of the new guidance, our project aims to gain insight into the swimming behaviour and performance of inanga (Galaxias maculatus) under various hydraulic conditions, in particular when swimming upstream, which is not well understood. For this purpose, we are designing a new experimental setup in a 600 mm wide flume at the Water Engineering Laboratory at the University of Auckland. We will study hydrodynamics of fish passes with roughened surfaces, baffles and energy dissipators. We will evaluate sensor equipment used to enable flow and fish tracking, with the intention of tracking individual inanga at critical cross sections. This will allow us to study fish response to turbulence, boundary layers, resting zones and wetted margins. We aim to gain valuable insight into design methods and materials that best help inanga, and potentially other members of the family Galaxiidae, with their migration. Eventually, the project aims to provide guidelines suitable for retrofitting existing and building new structures.