Fixing Fish Barriers
Earlier this year, we improved fish passage using a new technique to reconnect a section of Second Creek to the Main Credit River at Terra Cotta Conservation Area. In partnership with the Town of Caledon, we installed a floating fish ramp. This innovative retrofit to a perched culvert helps to improve the health of local fisheries by reconnecting the stream and allowing fish to live out their entire lifecycle. During their lives, fish migrate upstream and downstream to reproduce, feed and for other life cycle needs.
What is Fish Passage?
A fish passage refers to the ability of fish move freely through rivers and streams to find food, shelter and places to reproduce. In-stream barriers can harm fish by blocking their access to cooler water and safe habitats, especially during extreme weather caused by climate change. Some types of barriers that block fish movement include dams, weirs, perches and woody debris jams.
A perched culvert in Terra Cotta Conversation Area was the last barrier in Second Creek to the Main Credit River. By mitigating this fish passage barrier, we reconnected five kilometres of a cold-water stream that contributes to high quality brook trout habitat.
Understanding Perched Culverts
A culvert is a tunnel that lets water flow beneath roads, trails, railways or embankments. Usually made of metal pipe, stone or concrete, they keep water moving without disturbing what’s happening on the surface; whether it’s cars, bikes or wildlife passing overhead.
When improving fish passage at culverts, full replacement is usually preferred but not always possible. Retrofit solutions can improve connectivity until a full replacement is possible. In this case, we added the fish ramp to a culvert that already existed.
The culvert, located at Second Creek and the Caledon Trailway, was perched – meaning the downstream end of the culvert was elevated 1.2 metres above the pool below. A perch becomes a fish passage barrier when it is too high for fish to jump into the culvert from downstream to upstream.
Finding the Right Solution
The floating fish ramp adjusts to changing water levels, can fit various culvert sizes or shapes, and are easy to install with basic tools.
For this project, we chose a ramp with a textured surface, called dimples, to slow the water and help fish of all sizes swim through. The ramp was installed at a perch that already existed, giving fish the opportunity to swim up the ramp and cross through the culvert with ease. Without the ramp, the fish would hit a ‘dead end’ as they could not jump the perch and would not have access to the habitat available at Terra Cotta Conservation Area.
Monitoring the Ramp
To evaluate the retrofit, we’ll conduct regular checks and surveys where we catch and mark fish downstream, then return five days later to catch fish upstream and see if any marked fish have used the ramp. Monthly inspections also ensure debris is flowing through the ramp and is not piling up.
What’s Next?
This restoration project is an exciting milestone for our watershed. Through monitoring, we can see whether this new technology is successfully reconnecting fish habitat and support local fish communities through the entirety of their life cycle. If fish are found to use the ramp, we can d use the floating fish ramps at more perched culverts in the future. It can open the door to a new way of improving fish passage across the entire watershed.
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By Annie White, Aquatic Restoration Technician 2