Dams, culverts and weirs have been making almost half of Aotearoa New Zealand rivers partially or fully inaccessible to migratory fish, a new study shows.
Niwa has researched how river fragmentation could lead to freshwater biodiversity loss and found Aotearoa as having some of the highest densities of barriers to fish passage in the world, with approximately 0.16 barriers/km.
Niwa freshwater ecologist Paul Franklin said iconic species such as eels and whitebait have been endangered by human-made structures built along their migration cycle between the sea and rivers.
They often encounter different structures along the way that act as a barrier, stopping them from reaching key habitats. This ultimately leads to lower abundances and potentially loss of these species," Franklin said.
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"There are just over 50 native New Zealand fish species, with around 85% of those not existing anywhere else in the world.
Niwa has been studying how to help fish migrate and come up with a solution to the 48% of freshwater rivers that are inaccessible to migratory fish.
"We put fish into the equivalent of a water treadmill to see what speed they can maintain - we want fish to be able to move upstream casually, not having to fight the whole way.
IAIN MCGREGOR/STUFF
Water is the source of life on Earth, so why are we poisoning it?
We can then assess what adjustments need to be made to structures in our river networks to help fish pass through these environments more easily.
"The good news is that many of the solutions are extremely easy to implement. You can instal baffles into culverts, which are basically panels placed inside the tube that help to slow water down and create resting areas, so that fish can pass through into the stream above," Franklin said .
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Niwa has researched how river fragmentation could lead to freshwater biodiversity loss and found Aotearoa as having some of the highest densities of barriers to fish passage in the world, with approximately 0.16 barriers/km.
Niwa freshwater ecologist Paul Franklin said iconic species such as eels and whitebait have been endangered by human-made structures built along their migration cycle between the sea and rivers.
They often encounter different structures along the way that act as a barrier, stopping them from reaching key habitats. This ultimately leads to lower abundances and potentially loss of these species," Franklin said.
READ MORE:
* Christchurch waterways suffering 'urban stream syndrome'
* What will our beaches, lakes and rivers look like in 2050?
* Government funding for 'happier' fish in Southland streams and rivers
"There are just over 50 native New Zealand fish species, with around 85% of those not existing anywhere else in the world.
Niwa has been studying how to help fish migrate and come up with a solution to the 48% of freshwater rivers that are inaccessible to migratory fish.
"We put fish into the equivalent of a water treadmill to see what speed they can maintain - we want fish to be able to move upstream casually, not having to fight the whole way.
IAIN MCGREGOR/STUFF
Water is the source of life on Earth, so why are we poisoning it?
We can then assess what adjustments need to be made to structures in our river networks to help fish pass through these environments more easily.
"The good news is that many of the solutions are extremely easy to implement. You can instal baffles into culverts, which are basically panels placed inside the tube that help to slow water down and create resting areas, so that fish can pass through into the stream above," Franklin said .
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