Fish passage and wildlife corridors

Wildlife Corridors

Ecosystems function across a large scale, and many species need to move across the landscape to forage for food and find breeding partners. Wildlife corridors allow birds, lizards, insects and fish to travel between key areas and extend their habitats.

Wildlife Corridors, or Ecological Corridors, are a combination of trees, planted areas, and waterways that link significant ecological areas or habitats together. As well as enabling wildlife to travel through, these corridors also allow for seed dispersal so that native tree and plant diversity can be enriched. Enhancing or developing these corridors helps nature to flourish.

Increasing species diversity makes them more resilient to extreme weather events, pest infestations, diseases and other disasters. If multiple key areas are connected, it helps ensure the long-term survival of the species as they will be more diverse and robust.

Wildlife corridors can be small in size, through your garden or property, or they can cross property lines and even entire cities.

Tips to create or enhance existing wildlife corridors

• Think about connectivity when planning your restoration work. Consider the green spaces already there and see if you can join them together with planting. This will create a larger area, meaning more biodiversity. Even planting a few native trees in paddocks can help birds to travel from one bush area to another.
• Do your neighbours have bush on their property? Try to link your green areas with neighbouring bush or wetlands.
• Riparian zones along waterways function as wildlife corridors. Check out SBN's resource on waterways for steps and tips to restore waterways.
• For more info on caring for bush remnants, check out our care for what you've got resource. 

Fish Passage

Every waterway is a part of a network that stretches across the landscape. The actions you take will have effects on the health of the river both upstream and downstream. To achieve coordinated action, talk to your neighbours to join in restoration efforts along the whole length of the waterway.

A key action is to ensure that fish can have unrestricted access.

New Zealand native freshwater fish species

There are more than 51 species of native freshwater fish in Aotearoa New Zealand (plus unwanted invasive species too).

More than 75% of our native freshwater fish are currently threatened or at risk.

A number of our native fish are commonly known as whitebait, a seasonal delicacy and a taonga Treasured or prized. Referring to anything considered valuable, including culturally or socially. species for Māori as a traditional food source. Whitebait are juvenile fish of six native species, five of which are migratory galaxiid species (īnanga, kōaro, banded kōkopu, giant kōkopu & shortjaw kōkopu).

More than half of these species are threatened or at risk of extinction because of degraded habitats, fishing pressure and obstacles to fish passage.

Discover your freshwater fish species

A great first step is to visit a stream at night with a torch. Or take a bucket or net to have a closer look at some of the smaller species. It is very satisfying to see Tuna/Freshwater eels and native fish like Īnanga or Banded Kōkopu inhabiting your stream.

Don’t be discouraged if you don't see any fish, they are most likely there! Freshwater fish are very secretive, and even if you can’t see them it’s important to ensure their safe passage through the waterway.

Why is fish passage important?

Many native fish like Tuna and the whitebait species are migratory. This means that whilst they spend most of their lives in freshwater, they also spend part of their breeding life cycle in the ocean. For these fish, access to both the ocean and often up to the top of the freshwater catchment is essential for their survival.

Your property may be many kilometres from the sea or at the top of the catchment, but your waterway forms a key part of this aquatic highway. This is why providing safe fish passage is really important.

Ways to improve fish passage

How you fix a fish passage barrier depends on which fish species are present, their ability to move through the stream and the condition of the site. Start small. Determine which in-stream structures you have currently, and whether they can be improved.

The most effective way to restore fish passage is to completely remove the barrier. This isn’t always realistic, as we rely on many of these structures to aid our own access as well as stock access. Depending on the structure’s design and condition, it may need to be replaced. If this isn’t possible, there are usually easy ways to modify them. The following can be used as tools to fix barriers and assist fish. 

• Rock ramps
• Fish-friendly culverts (avoiding hung culverts)
• Backwatering
• Fish ladders
• Baffles
• Mussel spat ropes
• Bypass structures
• Fish-friendly flood/tide gates/pumps

Seek support from your regional council and local restoration consultants before undertaking any in-stream remediation work. Consider whether you will need resource consent and funding before you start. Local iwi and hapū groups may be able to provide knowledge and technical support for fish passage too.

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