Background
The Tube Fishway was designed to restore upstream fish passage past large dams (10m – >50m). However, it has since found application for smaller barriers (down to ~1m).
Millions of kilometres of formerly fish-accessible reaches in river catchments throughout the world are now isolated by dams and weirs. These reaches are critical for fish habitat or reproduction. Freshwater fish populations have consequently collapsed over the past 125 years.
Methods
Quantitaive comparison is made between Tube Fishways and conventional fishways for both large dams and smaller barriers.
Results
For higher dams, the trap-and-haul fishway system has similar capabilities to the Tube Fishway but is not widely practised internationally due to its labour intensiveness. Upstream transit times and fish handling with trap-and-haul are significantly greater than with Tube Fishways.
For smaller barriers, conventional fish ladders challenge fish swimming ability and may delay passage, affecting reproduction and increasing predation. Some fish ladders prevent passage by small or weaker-swimming species, while Tube Fishways are designed to pass diverse fish communities without requiring strong swimming ability.
Pipe-based fish transfer has been used widely and safely in the aquaculture industry for decades. These aquaculture-type systems are not applied to dams and weirs because pressure injuries are likely. The Tube Fishway has been designed specifically to keep fish at a near-constant pressure and well-aerated during transit.
Conclusion
This paper will illustrate Tube Fishway application to a range of barrier sizes in comparison with other fishway types.