Wiri Stream


Located just south of Manukau City are two large ponds approximately 1.5 hectares in size that surrounds a number of residences and reserve. It acts as both a feature and stormwater waterway that is home to many native fish and bird wildlife. In 2007, grass carp were released due to the rapid invasion of pest weeds (notably Egeria densa), which was both threatening to the wildlife as a health risk, and causing flooding to the site during high rainfall events.


The then Manuaku City Council and NZWR agreed that grass carp would be the most appropriate, and effective method. Other aquatic weed control methods are more costly, and the likes of herbicides and the mechanical removal of weeds results in considerable loss of aquatic life and can result in degradation of the habitat through rotting vegetation and disturbance of sediments; making it unsafe for humans or any other organism to consume safely. In a stormwater system this is important to avoid as the effects of such operations gets flushed downstream, eventually making it to the ocean. Once introduced the grass carp reduced the weed levels, allowed for the improvement of water quality and through on-going surveys it is evident that the fish are indirectly responsible for increased native fish presence.

Please note that this waterway is not open for fishing to the public, and course fishing is not permitted to anyone.


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