The effect of manipulated flows on fish kinematics and behaviour at migratory barriers

Sonnino Sorisio, Guglielmo ORCID: https://orcid.org/0000-0002-8757-3105 2024. The effect of manipulated flows on fish kinematics and behaviour at migratory barriers. PhD Thesis, Cardiff University. Item availability restricted.

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Abstract

Anthropogenic structures in rivers have caused the current state of the world’s freshwater bodies to become highly fragmented. This has caused an overall decline in biodiversity and has majorly impacted migratory fish populations by blocking their migration pathways. Fish passes are therefore required to allow fish to migrate past these obstructions and complete their life cycle, but each obstruction presents its own challenges and requires a separate solution. In this thesis, emerging threats and current fish protection measures are assessed and new passage solutions are tested through the consideration of fish behaviour and kinematic in response to the manipulated hydrodynamics produced by the passage solutions. The experiments were carried out in laboratory recirculating open channel flumes. The current European eel (Anguilla anguilla) screening regulations were tested with different screening materials, screen angles, and flow velocities (Chapter 2). The current regulations did not produce any impingement or entrainment of eels through the screens at velocities allowed by the regulations but started to occur when velocity was increased showing that the regulations give appropriate velocity ranges. Eel tiles were investigated as a possible solution for high velocity barriers, the hydrodynamic analysis (Chapter 3) revealed that over a range of flow conditions the tiles produced low velocity flow around them and shear layers when in contact with the open channel. Juvenile eels had higher passage rates with the presence of the tiles (Chapter 4) and were able to pass upstream with reduced swimming effort compared to eels not using the tiles. Three-spined sticklebacks (Gasterosteus aculeatus) similarly benefitted from the tiles and shoaling sticklebacks had significantly higher passage rates (Chapter 5). The shoaling dynamics of sticklebacks were therefore investigated (Chapter 6) and these analyses revealed that there is a hydrodynamic benefit to stickleback shoaling. The effects of shoaling on rainbow trout (Oncorhynchus mykiss) interacting with different hydrokinetic turbine configurations presented bolder behaviour towards the turbine in the trout and increased the fish’s usage of the turbine wake to reduce swimming effort (Chapter 7). By using colour to increase the contrast of turbine blades with the background, and unwanted turbine interactions that could potentially lead to impact with the rotor were decreased (Chapter 8). The overall findings from this thesis show that hydrodynamic conditions and behavioural factors are important when evaluating fish passage.

Item Type:	Thesis (PhD)
Date Type:	Completion
Status:	Unpublished
Schools:	Engineering
Uncontrolled Keywords:	Fish passage; European eel; Anguilla anguilla; Fish kinematics; Hydrodynamics; Hydrokinetic turbines
Date of First Compliant Deposit:	24 January 2025
Last Modified:	24 Jan 2025 14:24
URI:	https://orca.cardiff.ac.uk/id/eprint/175546

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