Why is fish passage important? - Alberta Ministry of Transportation

Report
Why is fish passage important?
• Migration for spawning
• Movement for survival, temperatures,
flows, available food and cover
• Prevent population fragmentation
• Avoid predators
• After a catastrophic event,
recolonization
Context for TRANS
TRANS projects are ‘linearly based’
with the occasional exception of
building reservoirs and canals.
TRANS is not large land scale
developers.
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We don’t do this type of
development:
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Rather we are focused on roads
and bridges as part of the
provincial highway network.
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And we’d rather avoid this:
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And create this:
Embedded (fish friendly) Crossings
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Most often, TRANS influences fish
movement through habitat
fragmentation not habitat itself.
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Biology Basics (as they relate to
fish passage)
"Fishes are the evolutionary
solution to a number of mechanical,
aural, optical, structural, electrical
and other engineering problems
relating to the environment in which
they exist.”
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“They are complex organisms, or
animals, and their sensory systems
have evolved to provide the
necessary functions to make the
whole fish a viable entity in the
watery environment"
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Fish have adapted to the underwater
environment
Many questions have come up
about culvert length based on
anthropogenic perceptions. Not
only to fish see better in water than
humans, they have a photo
spectrum outside of humans.
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“Fish have a well-developed sense
of sight, which allows them to find
food, cover, mates, and avoid being
eaten in the underwater "fish eat
fish world." Their eyesight is on par
with ours, as many fish species, but
not all, see color and some can
literally see in the dark.”
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Fish have other senses
"The lateral line system is a kind of
underwater sonar and is very
similar to the sonar-based
navigation system employed by
bats.
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But instead of listening to ultrasonic
squeaks bouncing back from solid
objects, the fish is able to feel the
movement of water reflected back
against its body from objects around
it.”
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In other words, fish have abilities
that are not well understood.
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What is known about fish swimming
capabilities?
Short Answer:
Not a lot.
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Swimming Abilities of Fish
Three forms of swimming which are
predominant in fish species found
in
Alberta include:
 Anguilliform
 Subcarangiform
 Esosiform
Anguilliform
• Burbot (freshwater ‘cod’)
• Swim in an ‘eel-like fashion
(undulating)
Subcarangiform
• Bull Trout
• Swim using the anterior part of
theirs bodies (e.g. tail)
Esosiform
• Northern Pike
• Swim using both characteristics of
both anguilliform and subcarangiform
Swimming terms
 Burst Speeds – highest speed;
endurance less than 20 seconds
but some fish can burst up to 60
seconds (300mm Rainbow Trout
can burst up to 4.3 m/s and NPike
can burst up to 2.0 m/s)
 Prolonged – intermediate
swimming speeds; endurance 20
seconds to 30 minutes
 Sustained – low speeds
maintained indefinitely
Culvert structures are designed
with appropriate hydraulic
conditions that will allow the fish
species that are present to swim
through the structure within a
specific range of flows.
How does this all relate to fish
passage in culverts?
Contrary to popular belief, fish do not
automatically come up to a culvert and
turn around and go away.
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Fish swimming abilities
The ability of fish to move is controlled
by a number of factors including but not
limited to:
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Fish species type
Body morphology
Behavior
Motivation
Energetics
Temperature
Physiology
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A familiar reference is Katopodis and
Gervais (1991) who produced fish
endurance and swimming distance
versus water velocity curves. The
authors meant these curves to used
as guidance since they are so
conservative.
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• Example: Swimming Performance Assessment
– Subcarangiform Mode (Katopodis and
Gervais 1991)
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Most of the data was obtained in
laboratories where fish were
generally put inside a tube or flume,
zapped with electricity to get them
moving, and then water velocities
were incrementally increased until
the fish reach fatigue.
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Very ‘cranky’ bull trout in a swim
tube
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As to the swimming performance
curves, many people used the
numbers as ‘absolutes’ rather than
guidance.
If those curves were actually true,
we would have virtually no fish in
Alberta (or even the rest of Canada).
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However, field studies (including
TRANS’ work) have solidly proven
that fish swimming abilities have far
exceeded those predicted by theory.
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It has been found that fish are able
to successfully pass through
culverts at higher average velocities
than the velocities predicted in
laboratory studies.
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Dependent on the fish species ,
many have different modes of
swimming . Fish tend to be
energetically efficient – they will
seek out lower velocity zones when
migrating and will do so in culverts if
needed.
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Culverts do have slower velocity area
(margins) along the walls and bottom.
Slope = 0.5%, flow = .0145 cms, Average
velocity = .872 m/s (Illustration of culvert
velocities [Magura, 2007])
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Information on swimming abilities,
behavior, energetics and other areas
of fish biology are being explored
more and more.
But now more to the engineering
side of things.
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