Monitoring and maintenance
Once you have identified the problem, and applied the necessary tools for restoring fish to your stream, the next phase of your project is to monitor the stream site to see whether restoration works.
Monitoring your project is essential for discovering what worked, what didn’t, and what can be changed for future restoration. Many community-based projects are not monitored, and it is possible that while a stream might look better, its fish populations may not have improved. Ideally, a successful monitoring programme should involve before/after fish surveys.
Fish recruitment varies significantly from year to year, and for that reason fish surveys should be conducted each year for 3-6 years. Ideally, a summer survey should be carried out each year for at least 3 years before restoration to establish a valid baseline, and then for 3 years post-restoration.
Where restoration is limited to riparian planting, which can take 5-10 years before any major changes are noticeable, post-restoration surveys are best left for at least 5 years. It may also be useful to make comparisons with streams similar to the one you restored.
Methods for carrying out fish surveys in streams need to be customised to the type of work that you carried out. In general, electric fishing is the best method for fish surveys, but vital information can also be obtained on some species using spotlighting (at night), as well as nets and traps. Consult a qualified and experienced fish ecologist to determine the best way to monitor your stream.
Annual inspection and maintenance during the early stages of recovery is strongly advisable. By inspecting the site early on, you can identify and forestall any problems that may eventuate, such as fish-pass malfunctions, blockages, dying plants or changes in stream flow.
There are currently few case studies for fish restoration projects as this is a relatively new and developing field. Few sites have strong evidence from which we can say restoration worked or failed. However, several rural streams draining from the Hakarimata Ranges down to the Waikato River were restored via fencing and riparian planting over 10 years ago, and the results have been well documented. Similarly, information is available on an urban restoration project in Christchurch.
Special Issue of New Zealand Journal of Marine and Freshwater Research, (vol. 43 2009) on Aquatic Restoration (32). Fish restoration studies are described in this paper.