Our region is home to at least 14 species of native fish. As part of their natural life-cycle, 12 of these species need to migrate between freshwater rivers and streams and the sea.
This type of life-cycle (known as diadromy) is common amongst New Zealand freshwater fish. Fish species that undertake this type of migration include some of our country's most popular recreational fishing species. These include the 5 native species that are collectively known as whitebait and longfin and shortfin eels.
The survival of many of our native freshwater fish species depends on being able to move freely within waterways.
Barriers to fish passage
Migrations of native fish can be blocked by barriers in rivers and streams.
Some of these barriers are natural like waterfalls and large rapids. However, artificial structures such as flood gates, weirs and dams can prevent native fish from completing the migration phase of their life-cycle needed for successful reproduction.
Even small artificial structures such as culverts can act as barriers to fish, they can prevent fish from moving between habitats, affecting their abundance and distribution.
Artificial barriers to fish movement have contributed to the decline of our native freshwater fish populations, and the quality of our freshwater ecosystems.
The National Policy Statement for Freshwater Management 2020 (NPS-FM 2020) requires regional councils to produce an action plan.
The plan is to provide for fish passage and include an objective in our regional plan that states that ‘the passage of fish is maintained or is improved by instream structures, except where it's desirable to prevent the passage of some fish species in order to protect desired fish species, their life stages, or their habitats’. This is because some introduced species such as trout are predators of native fish species.
For more information - Essential freshwater: Fish passage fact sheet
All landowners have a responsibility to allow for fish passage when managing or creating structures in watercourses under the Fisheries Regulations 1983.
The new National Environmental Standards for Freshwater have requirements relating to the installation of new culverts and weirs, flap gates and dams.
For example as a permitted activity, culverts are fundamentally required to provide for the same passage of fish upstream and downstream as would exist without the culvert (except during associated works).
More information - Essential Freshwater: Fish passage fact sheet and guidelines
How you can help
If you plan to carry out works in a watercourse on your property or development site, you should consider how this might affect fish passage.
For more information on maintaining or restoring fish passage, The New Zealand Fish Passage Advisory Group advocates the use of the national fish passage guidelines.
Key guidance
- Regulations for fish passage
- Considering fish passage in the design of new instream structures
- How to fix fish passage barriers at existing instream structures
- Temporary culverts and fish passage
We can also advise you on how to make sure any new structures allow for fish passage and if resource consents may be required. For any questions around resource consents, please contact our regional planners regional.consents@gdc.govt.nz