Since March 2019, all in-stream structures such as culverts and weirs must be accessable for fish to swim through. These accessable structures within streams are known as fish passage
Start with this brochure about fish friendly culverts and rock ramps in small streams.
Detailed best practice guidelines have been prepared to assist regional and local authorities, consultants, roading engineers and contractors with the design of appropriate waterway crossings within the Tasman District.
The topics covered by this best practice guideline handbook include:
Sixteen of the 20 native freshwater fish that call Tasman District's rivers home need to "commute" to the sea as part of their lifecycle. The whitebait fishery depends on this migration, along with good stream habitat. While some fish can climb, they just can’t jump! They also cannot swim upstream if the speed of the water is too fast.
So, a culvert that is undercut (usually at the downstream end) or forces water through at high speed, could end the chances of most fish inhabiting the waterway upstream. Collectively about 25% of all culverts in Tasman have been found to be a barrier to fish migration. This is a major issue - if fish can't migrate, they can't breed.
We keep a database of all in-stream structures and include information such as photos, measurements of height of overhang and distance undercut, culvert size and material, average stream width, depth and flow, and habitat quality upstream. As work programmes allow, these structures are being improved when other upgrades are being undertaken.
If you have a driveway, farm raceways/laneways, or roads of any sort that cross waterways, there is a chance that the culvert will be preventing fish passage for all but eels. The solution if often as simple as attaching a piece of conveyor belt and mussel spat rope.
The Council is happy to provide these materials, and even attach it to make them fish-friendly at no cost to you.
Contact Trevor James at the Council for assistance with making your culvert fish-friendly.
Ph. 03 543 8400