Gravel-lined upstream fish passes: Construction guide
upstream, New Zealand, eels, fish population, life cycle, upstream migration, migration, juvenile, streams
Consultancy Report DOC003
Hamilton, New Zealand
None supplied. Introduction: Continuing pressures on many of New Zealand's native freshwater fish species has seen a substantial decline in their numbers. This decline has serious implications for New Zealand, both economically and ecologically. Several of the freshwater species (primarily eels and whitebait) generate sizeable revenue, while any decline in the fish populations, which are part of our natural heritage, affects the richness and diversity of New Zealand's fauna. Most of New Zealand's native freshwater fish are diadromous; this is they are obliged to migrate between the sea and freshwater to complete their life cycles. Many make extensive upstream migration as juveniles. These young fish are generally poor swimmers who make use of low-velocity zones on the edges or bottom of rivers and streams to make their way upstream. Some species have evolved climbing abilities that enable them to surmount waterfalls and rapids. The gravel-lined fish pass described in this guide capitalises on this behaviour.