Fish Passage Action Team Blog
Stories, updates, and insights from the field — tracking progress, sharing wins, and supporting better fish passage around the world.
Sustainability Award
Hi everyone,
A big congratulations to our friend Mike Thomas for being awarded the Downer Sustainability Award.
The team at ATS Environmental were privileged to help Mike modify the RAMMs asset management app to include data that allows Downer and Tasman District Council to identify, remediate and manage fish barriers across their road network.
Many roading authorities in NZ use RAMMs as their primary asset management tool, so there will be significant savings in meeting the regulatory requirements by monitoring structural integrity and fish passage in the one site visit.
Thanks everyone, and good on ya Mike!
World Fish Migration Day
Fish Passage Remediation Training Aid launch.
Hi everyone, We have been working away and are excited to announce the launch of the latest Fish Passage Training Aid and Fish Passage Action Team website!
This has been launched in conjunction with World Fish Migration Day, we hope you find it useful, and we are always open to comments and feedback.
You’ll always be able to find the latest version on the Fish Passage Action Team website under our Fish Passage Resources tab, in the section Educational tools. We hope you have a good rest of your weekend.
Fish Passage Remediation Washington, USA
Hi everyone,
We have recently received this video showing fish passage restoration in Whatcom County Washington.
One of our team members; the director of SSA Environmental, Shane Scott, has been working hard to restore culverts/weirs across the United States.
We absolutely love seeing restoration work done around the world.
Shane has worked with the Nooksack Salmon Enhancement Association to install Flexi-Baffles to increase the depth and reduce velocity in this fast-flowing culvert.
Fish Passage Webinar
Hi Everyone,
We hope everyone is safe and well!
We loved listening to Kelly Hughes (of ATS Environmental) speak for the EIANZ Webinar covering the big picture fish passage subject.
So much so that we’ve taken the recorded webinar and posted it to our YouTube channel for all the people who missed it.
Webinar invite | Managing assets with respect to meeting fish passage requirements
Changing the narrative towards mass remediation across infrastructure networks.
Everyone passionate about restoring fish passage and reconnecting waterways should take the time to sit in on this webinar. https://www.eianz.org/events/event/webinar-managing-assets-with-respect-to-meeting-fish-passage-requirements It is on Wednesday 9th March – 3 PM NZDT
Mussel-Rope Part Two
Further to our recent mailout where we discussed mussel rope at perched/overhanging structures, it’s now time to look at mussel-rope when placed within culverts.
Mussel-rope is one of the tools that can be used to help improve fish passage where fast, laminar flow is present.
If it is not viable to remove an existing culvert or is not practical to fit baffles due to the small diameter (e.g. under 750mm or 2 &1/2 feet), then mussel-rope can be considered as a remediation tool.
Obviously, the rope does not retain bed material, create rest-pools or the complexity that baffles do. Therefore rope should only be used as a last resort, and it should not be used at new culvert installs.
Below are some CFD images that show the effects the mussel-rope has on the depth and velocity in culverts.
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12Lt/sec
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Understanding Mussel-Rope
Understanding Mussel-rope Part 1
Many culverts are barriers to fish due to being perched/overhanging or having fast laminar flow.
In the video below, Tim demonstrates how mussel-rope can improve fish passage at perched/overhanging structures.
The rope simulates natural tree roots and fibres that some species have evolved to utilise when migrating upstream.
The type of rope being used here is “looped mussel-rope”.
Looped rope is proving to be an effective remediation tool at perched/overhung structures. It also has the benefit of not shedding fibres as readily as other types of ropes.
Fish Passage Guidelines
| Hi everyone The Fish Passage Action Team have been working on a simple one-page guide to help with the remediation of common structures causing a barrier to fish. The guide includes a link to an interactive decision tool and some helpful before & after examples. Happy holidays! |
 Fish Passage Remediation (existing structures) Overview Fish passage remediation is less about target species, specific swimming speeds, average velocities, Mannings numbers etc., and more about understanding the medium in which fish have evolved to navigate, i.e. water, with the dynamics of complex flows and boundary layers all at a fine resolution. Basic principles – “Match or better” the streamflow characteristics. – Provide complex flows (non-laminar) – multi-directional flows with rest pools. – Length of fast flow zones between rest pools must be shorter than fish burst-swim capabilities. – Provide sufficient depth. – Ensure continuity – no overhangs. – Give fish a range of navigation path options. – Ideally, retain bed material. General rules. – Rope should not be used in culverts if baffles can be fitted, even if climbing species are targeted. – Ramps should include splash zones and substrate, e.g. rope. – Ramps should extend into the plunge pool as far as practicable. – Baffles should be spaced so that the rest pool from one extends easily up to the next. – Baffles may be considered artificial bed material in some situations, i.e. create similar hydrological conditions – If rope is fitted through a culvert that is also perched, a second set of rope should be fitted at the outlet. – Rope should only be attached at the upstream end. – Interventions should not significantly reduce culvert capacity or increase the risk of debris jams. – Tide-gates should be designed/modified to delay the closing as long as possible. Which tools to use where? The above principles help to guide us towards selecting appropriate remediation tools. For more detailed guidance on the use of remediation tools click here: Remediation Decision-Tree Interactive Tool Before & after examples click here:https://ats-environmental.com/before-after-remediation/ Measures of success: Success should be outcome-focused and easy to measure or observe. – Complex flows similar to stream (depth, width, velocities) – Bed material retained. – Continuity – no perch or overhang. – Extended opening period for tide gates. Please note that the linked resources above are kindly provided by ATS Environmental. |
Comparing Baffle Types in Round Culvert
Hi everyone,
We hope you are staying safe and well.
As shared a short while back, we have started using Computation Fluid Dynamics (CFD) to solidify what we already knew about culvert/weir baffles and their fish passage improvement features.
CFD is a powerful engineering tool used to simulate the action of fluids in a structure at a resolution not normally visible to the human eye.
It is well known that fish prefer deep water, complex flows and lower velocity, so it is exciting to see just how much of an impact different types of baffles have on the flow dynamics.
The independent CFD simulation was able to demonstrate the depth, and changes to velocity, with and without baffles installed.
The baffles included in this study were, Type 1 Spoiler Baffles, Type 3 Spoiler Baffles and Flexi-Baffles.
Below is a link to a Glide-show and we hope you find it as interesting as we did!
Contact the Fish Passage Action Team if you want to know more, and perhaps run a simulation on a structure that you are planning to remediate.
Mini-Hydro Intake Weir
Hi everyone
Below is a photo showing modifications to a back-country mini-hydro intake weir.
The original fish pass and minimum residual flow devices were not functioning.
The new design successfully allows expected species, all of which are climbers – longfin eels, and some migratory galaxiid along with invertebrates, to migrate upstream.
The fish passes comprise a flexible rubber channel (2 x Flexi-baffles) lined with looped mussel-rope. The rope is only attached at the upstream end to avoid debris jams.
The Minimum residual flow is controlled by another flexible baffle that pushes water to sides before overtopping.
Please contact the Fish Passage Action Team for more detailed information.
Join our mail-out!
“99% of barriers in Rangitaiki fixed with simple solutions under $200”
– RNZ on ATS Environmental initiative
“Installed flexible baffles in culvert—juvenile galaxiid seen migrating days later.”
– Nelson City Council Trial Update
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