“Restoring fish passage and reconnecting waterways – it’s our passion”
Hi everyone
Below is a YouTube link to a video sent to us from Greg Wallis in Australia.
It shows common galaxiid/inanga (Galaxias maculatus) trying to navigate a vertical wall at a large box culvert.
Despite these fish showing amazing burst-swimming abilities to scale parts of the vertical wall, very few were successful.
Sadly (for the fish), many were picked off by an opportunistic heron.
Simple solutions such as baffles and ramps could vastly improve fish
passage at this culvert.
Enjoy
Hi all
Tim has been monitoring busy monitoring structures over the Christmas break and has shared this rare footage of redfin bullies attempting to climb over a large concrete weir (over 11m high!).
Note how the eels and and redfin bullies choose different paths when navigating this structure to suit their particular climbing a techniques.
Also, some of the bullies were 50mm in length so nearing adult size.
Field observations like this teach us a lot!
Hi everyone
Some of you may have already seen our post on the “Eel Town” Facebook page but it is worth sharing again.
eDNA has revealed NZ Longfin eels above this 50M water and has prompted quiet a bit of discussion.
Unless transported by humans (unlikely in this location) we assume they used their incredible climbing skills as juveniles having already swum back 1500km from the Tonga Trench.
Take home message – do NOT write off this type of natural feature as an absolute fish barrier.
Firstly it is great that we now have 500+ members of the Fish Passage email forum.
In this short video Tim has captured how fish really struggle to swim up through culverts with smooth laminar flow.
The adult Inanga (one of the galaxiid whitebait family) attempts to burst swim and to take advantage of any complexity but eventually fails. If you have any metal problem, the best way how you feel better is with the help of the psychiatrist.
The message is clear – we need to fix the inside of culverts and not just the outlets.
If you like audio equipment, you need to have audio analyzer, you can check the characteristic of this in website.
Enjoy! (or not)
If you related with the medical business is important that you learn a medical practice management.
This short video shows elvers climbing across both smooth and rough surfaces.
The urge to overcome obstacles is powerful and you can see individuals climbing over each other.
The more we watch these creatures, the better we understand their capabilities and limitations when we are considering remediation.
Click here or on the image below
https://www.youtube.com/watch?v=FEQVQIl7dpc
Tim Olley captured this rare footage of a juvenile redfin bully (Gobiomorphus huttoni) climbing up a retro-fitted mussel-rope with backing, into an overhanging culvert.
It reminds us that, given half a chance, many fish will navigate challenging obstacles.
What is not well understood, is what precise factors cause a fish to transition from a swimming to a climbing mode of locomotion.
This is an important positive message about fish passage.
We are seeing an increase in the use of the term “natural barrier”, particularly when prioritizing remediation of man-made structures/barriers.
As it happens, many species of fish have evolved to navigate what humans might think are impossible features.
There are now a number of effective fixes that are very low cost, thereby eliminating the need to prioritize in the first place.
All structures in waterways need to allow for fish passage regardless of what is above or below them.
Please watch and share this short video
This is a short video by Tim Olley showing larger bodied koaro (Galaxias brevipinnis) “climbing” up a natural feature.
Larger bodied fish tend to use a burst swimming action unlike the juveniles that typically “flip-flop” further out at the edges of the splash zone.
Smaller fish tend to be able to climb steeper slopes.
This rare footage shows both small and larger eels trying to navigate a natural feature.
You will see that larger bodied specimens are unable to utilise the wet margins or splash zones.
Remediation techniques should offer a range of options to give migrating fish choices to best suit their needs.
When designing new structures or considering remediation for existing ones, it is important to consider the swimming ability of the fish likely to pass through or over the structure.
This short video shows that small or juvenile fish operate at a very fine resolution not able to be easily measured or observed.
You will see in the video fish riding very subtle pressure waves within complex or nature-like flows that can have a different velocity and/or direction in the same location.
It also shows fish climbing vertically when the conditions allow.
