Loss of habitat connectivity due to anthropogenic structures is among the greatest threats to freshwater fish populations. Re-establishing river connectivity through fish pass facilities can be an effective and cost-efficient method of enhancing local productivity, yet many are unsuccessful. A good understanding of multispecies swimming performance and behavioural response to hydraulic conditions is therefore needed to improve designs. This thesis aimed to improve knowledge in this field for non-salmonid fish species of conservation concern and economic value. Swimming performance data were collected for juvenile bighead carp (Hypophthalmichthys nobilis), a species threatened by anthropogenic barriers in China, using a range of swim chamber and open channel flume methodologies. Burst swimming performance was relatively weak, especially where multiple high velocity areas had to be passed. In addition, the availability of low velocity areas in a section of open channel flume did not improve endurance, and beyond aerobic swimming speeds these velocity refugia were rarely utilised. Management recommendations for fish pass velocities are presented based on this data. To further explore carp behavioural utilisation of low velocity regions, juvenile common carp (Cyprinus carpio) swimming performance and behaviour were evaluated under various wall roughness treatments. Fish generally maintained position close to smooth walls and small corrugations, yet often moved further from medium and large corrugations and into areas of higher velocity and lower turbulent kinetic energy. Thus, performance was not enhanced by the larger areas of low velocity created by corrugated walls. To assess the influence of accelerating flow on European eel (Anguilla anguilla) behaviour, a constricted flume created a velocity gradient representative of that found at anthropogenic structures and downstream bypass facilities. Of 138 downstream moving silver eels approaching the constriction, 46% reacted by changing orientation and/or a rapid burst of upstream swimming. Furthermore, 36% rejected the constricted channel and returned upstream, delaying downstream passage. The probability of a rejection was increased by a high abundance of the invasive parasite, Anguillicoloides crassus. These findings have potential implications for bypass efficiencies and escapement to sea. Eel swimming performance and behaviour were also evaluated during upstream passage through a culvert. Traditional corner baffles and prototype sloped baffles improved passage success compared to a bare culvert. Although the prototype created higher barrel velocities and turbulence, eel passage success was equal between the two baffle designs. Installation of the sloped baffle is recommended due to high passage efficiency and the potential to reduce the risk of debris accumulation compared to 90° baffles. The data presented in this thesis enhances our understanding of non-salmonid swimming performance and behaviour, and are used to recommend approaches to fish pass design for European eel and Asian carp.
| Identifer | oai:union.ndltd.org:bl.uk/oai:ethos.bl.uk:678159 |
| Date | January 2015 |
| Creators | Newbold, Lynda Rhian |
| Contributors | Kemp, Paul |
| Publisher | University of Southampton |
| Source Sets | Ethos UK |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
| Source | https://eprints.soton.ac.uk/385313/ |
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