Monitoring Freshwater Fish

Tasman District Council has carried out fish surveys annually since 2006. This page details how the work is carried out.

The aim of the surveys is to determine the effect on fish populations with varying habitat condition. This is achieved by comparing the diversity and abundance of freshwater fish in streams of a natural state with those that have been modified in various ways. The surveys also assess the success or otherwise of stream restoration projects, as well as gather information that can be used to better predict fish distribution in the future.  

Co-operation with Other Agencies

Tasman District Council monitors freshwater fish in cooperation with the Department of Conservation and Fish and Game NZ. All three organisations share responsibility for monitoring fish populations under a range of legislation and it works out efficiently to work together.  

Methods Used in Freshwater Fish Surveys

Freshwater fish in wadeable streams are sampled by backpack electric fishing, spotlighting and, in some circumstances, traps or nets. Fish are identified, sized and released. The methods used very rarely harm the fish. Over 30 sites are sampled each year, but only six are sampled on an on-going basis.

Along with the fish surveys an assessment of habitat is also recorded. Several parameters are measured: Channel size and depth; cover; riparian vegetation; channel gradient; streambed substrate size distribution; clearance of riparian vegetation; bank disturbance; and channel modification. 

Trout populations in the larger rivers are sampled using drift-diving methods. These are carried out annually at a range of sites and organised and managed by Fish and Game NZ.

Publications and Reports

Contact Us

If you have any further questions, please contact Trevor James, Resource Scientist