Wednesday, 1 November 2017

Evaluation of Christchurch City Council's riparian management trial

Christchurch City Council (CCC) recently changed its riparian vegetation clearance practices for a trial period in the summer of 2016/17. While the trial has wider objectives around improved environmental outcomes, īnanga spawning habitat is directly affected by bank cutting and other forms of vegetation clearance. A survey of īnanga (Galaxias maculatus) spawning habitat was completed in April 2017 to evaluate effects of the trial.

Benefits of the trial included increasing the availability of high quality spawning habitat and the discovery of new spawning sites. The Avon/Ōtākaro supported a relatively high area of occupation (AOO) of spawning sites for a single month in comparison to other years. In the Heathcote/Ōpāwaho spawning was found at new sites including upstream of Opawa Road. However, egg production was relatively low in the Heathcote/Ōpāwaho versus the same month in previous years. This suggests a shift in the month of peak spawning activity or a possible adult population decline and requires consecutive month surveys to confirm the actual trend.

The full report is available on the CCC website here:
Response of īnanga spawning habitat to riparian vegetation management