A recent study has discovered a way to help fish overcome the barrier posed by culverts.
Culverts have become a major part of our lives, allowing water to pass underneath a road, path, or some other structure.
However, for fishes, culverts can split up a habitat, block their movement from one place to another and even prevent them from evading predators. They have been identified as a significant contributor to the decline of freshwater fish populations globally.
According to Dr Jabin Watson, a research postdoctoral fellow at the School of Biological Sciences at The University of Queensland, such barriers (including dams, weirs, etc) are "a major contributor to the declines and local extinctions of many Australian fish species." This is because when streams pass through a culvert, the water flow is concentrated and much faster, and this makes it harder (or impossible) for small fish and juveniles to swim through.
In some cases, baffles are frequently used to address this problem. However, the resultant turbulence can knock the fish about and cause them to be disoriented.
To address this problem, Watson, together with other researchers from the Threatened Species Recovery Hub, has come up with a solution to this problem—by adding a beam along one side of the culvert, so as to create a boundary layer, which is a channel of slower-moving water along one side of the culvert.
Dr Jabin Watson, explaining the research undertaken for this study.
This approach has proved to be very successful in laboratory trials, allowing the small fish and juveniles to make their way along fast-flowing water.
"Strategies that work to improve fish passage provide hope for our freshwater species," said Watson.
The findings of the study have been published in Volume 122 of the journal Ecological Engineering.