Lake Serpentine Pest Fish Barrier Options

Thursday, 05 November 2009

In May 2009 a WCEET funded workshop of New Zealand experts was held to consider the feasibility (including possible designs) of pest fish barriers for installation at Waikato lowland lakes –with a particular view to testing a trial design at the outlet of the Lake Serpentine (Rotopiko) complex. 

Nutrients, sedimentation and the presence of pest fish are key contributors to the decline in wetland biodiversity and water quality.  Exotic fish are  found in all Waikato lakes.  At Lake Serpentine, the Waikato’s highest biodiversity ranked Waikato lake, pest fish present include rudd, goldfish and catfish.  Each species cause harm in different ways such as competing for food with or predating native fish and eating or dislodging native plants from the lake bed.

There was good agreement amongst participants that a barrier was required at the site.  Further work is required including understanding more about: the lake and outlet stream hydrology and the ecology and behaviour of the pest fish present including other species that may enter the lake.

Planning and investigation is continuing on a number of hydrological and biological matters in order that background data and an improved awareness of the kinds of issues and problems that may arise can be considered.  It is expected Phase II -detailed design on both barrier and eradication techniques will commence next year.